Remove adt_def from projections and downcasts in MIR

[tmandry]

As part of optimizing generator layouts in MIR, we'd like to allow downcasting generators to variants which do not have a corresponding def_id, since they are created by the compiler.

This refactor hopes to allow that, without regressing perf.

r? @eddyb

[eddyb]

@bors try

[bors]

⌛ Trying commit f4a1628 with merge 24a40d8...

[rust-highfive]

The job x86_64-gnu-llvm-6.0 of your PR failed on Travis (raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

travis_time:end:001168ec:start=1553830693456851826,finish=1553830695802015183,duration=2345163357
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
$ export GCP_CACHE_BUCKET=rust-lang-ci-cache
Setting environment variables from .travis.yml
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[01:13:10] 
[01:13:10] 269 LL |         drop(x);
[01:13:10] 270    |              - mutable borrow later used here
[01:13:10] 271 
[01:13:10] - error[E0502]: cannot borrow `e.x` as immutable because it is also borrowed as mutable
[01:13:10] + error[E0502]: cannot borrow `e.0` as immutable because it is also borrowed as mutable
[01:13:10] 274    |
[01:13:10] 275 LL |         let x = &mut e;
[01:13:10] 
[01:13:10] 
[01:13:10] 
[01:13:10] The actual stderr differed from the expected stderr.
[01:13:10] Actual stderr saved to /checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/borrowck/borrowck-describe-lvalue.mir/borrowck-describe-lvalue.mir.stderr
[01:13:10] To update references, rerun the tests and pass the `--bless` flag
[01:13:10] To only update this specific test, also pass `--test-args borrowck/borrowck-describe-lvalue.rs`
[01:13:10] 
[01:13:10] error in revision `mir`: 1 errors occurred comparing output.
[01:13:10] status: exit code: 1
[01:13:10] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--cfg" "mir" "--error-format" "json" "-Zui-testing" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/borrowck/borrowck-describe-lvalue.mir/a" "-Crpath" "-O" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-Z" "borrowck=mir" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/borrowck/borrowck-describe-lvalue.mir/auxiliary" "-A" "unused"
[01:13:10] ------------------------------------------
[01:13:10] 
[01:13:10] ------------------------------------------
[01:13:10] stderr:
[01:13:10] stderr:
[01:13:10] ------------------------------------------
[01:13:10] {"message":"cannot borrow `x` as mutable more than once at a time","code":{"code":"E0499","explanation":"\nA variable was borrowed as mutable more than once. Erroneous code example:\n\n```compile_fail,E0499\nlet mut i = 0;\nlet mut x = &mut i;\nlet mut a = &mut i;\n// error: cannot borrow `i` as mutable more than once at a time\n```\n\nPlease note that in rust, you can either have many immutable references, or one\nmutable reference. Take a look at\nhttps://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html for more\ninformation. Example:\n\n\n```\nlet mut i = 0;\nlet mut x = &mut i; // ok!\n\n// or:\nlet mut i = 0;\nlet a = &i; // ok!\nlet b = &i; // still ok!\nlet c = &i; // still ok!\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":9625,"byte_end":9631,"line_start":284,"line_end":284,"column_start":21,"column_end":27,"is_primary":false,"text":[{"text":"            let y = &mut x;","highlight_start":21,"highlight_end":27}],"label":"first mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":9645,"byte_end":9651,"line_start":285,"line_end":285,"column_start":13,"column_end":19,"is_primary":true,"text":[{"text":"            &mut x; //[ast]~ ERROR cannot borrow `**x` as mutable more than once at a time","highlight_start":13,"highlight_end":19}],"label":"second mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":9826,"byte_end":9832,"line_start":287,"line_end":287,"column_start":13,"column_end":19,"is_primary":false,"text":[{"text":"            *y = 1;","highlight_start":13,"highlight_end":19}],"label":"first borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0499]: cannot borrow `x` as mutable more than once at a time\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:285:13\n   |\nLL |             let y = &mut x;\n   |                     ------ first mutable borrow occurs here\nLL |             &mut x; //[ast]~ ERROR cannot borrow `**x` as mutable more than once at a time\n   |             ^^^^^^ second mutable borrow occurs here\nLL |                     //[mir]~^ ERROR cannot borrow `x` as mutable more than once at a time\nLL |             *y = 1;\n   |             ------ first borrow later used here\n\n"}
[01:13:10] {"message":"cannot borrow `x` as mutable more than once at a time","code":{"code":"E0499","explanation":"\nA variable was borrowed as mutable more than once. Erroneous code example:\n\n```compile_fail,E0499\nlet mut i = 0;\nlet mut x = &mut i;\nlet mut a = &mut i;\n// error: cannot borrow `i` as mutable more than once at a time\n```\n\nPlease note that in rust, you can either have many immutable references, or one\nmutable reference. Take a look at\nhttps://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html for more\ninformation. Example:\n\n\n```\nlet mut i = 0;\nlet mut x = &mut i; // ok!\n\n// or:\nlet mut i = 0;\nlet a = &i; // ok!\nlet b = &i; // still ok!\nlet c = &i; // still ok!\n```\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":10042,"byte_end":10048,"line_start":295,"line_end":295,"column_start":28,"column_end":34,"is_primary":false,"text":[{"text":"                   let y = &mut x;","highlight_start":28,"highlight_end":34}],"label":"first mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":10069,"byte_end":10075,"line_start":296,"line_end":296,"column_start":20,"column_end":26,"is_primary":true,"text":[{"text":"                   &mut x; //[ast]~ ERROR cannot borrow `**x` as mutable more than once at a time","highlight_start":20,"highlight_end":26}],"label":"second mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":10256,"byte_end":10262,"line_start":298,"line_end":298,"column_start":20,"column_end":26,"is_primary":false,"text":[{"text":"                   *y = 1;","highlight_start":20,"highlight_end":26}],"label":"first borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0499]: cannot borrow `x` as mutable more than once at a time\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:296:20\n   |\nLL |                    let y = &mut x;\n   |                            ------ first mutable borrow occurs here\nLL |                    &mut x; //[ast]~ ERROR cannot borrow `**x` as mutable more than once at a time\n   |                    ^^^^^^ second mutable borrow occurs here\nLL |                    //[mir]~^ ERROR cannot borrow `x` as mutable more than once at a time\nLL |                    *y = 1;\n   |                    ------ first borrow later used here\n\n"}
[01:13:10] {"message":"captured variable cannot escape `FnMut` closure body","code":null,"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":9942,"byte_end":10309,"line_start":294,"line_end":300,"column_start":16,"column_end":18,"is_primary":true,"text":[{"text":"               || { //[mir]~ ERROR captured variable cannot escape `FnMut` closure body","highlight_start":16,"highlight_end":88},{"text":"                   let y = &mut x;","highlight_start":1,"highlight_end":35},{"text":"                   &mut x; //[ast]~ ERROR cannot borrow `**x` as mutable more than once at a time","highlight_start":1,"highlight_end":98},{"text":"                   //[mir]~^ ERROR cannot borrow `x` as mutable more than once at a time","highlight_start":1,"highlight_end":89},{"text":"                   *y = 1;","highlight_start":1,"highlight_end":27},{"text":"                   drop(y);","highlight_start":1,"highlight_end":28},{"text":"                }","highlight_start":1,"highlight_end":18}],"label":"returns a closure that contains a reference to a captured variable, which then escapes the closure body","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":9923,"byte_end":9924,"line_start":293,"line_end":293,"column_start":13,"column_end":14,"is_primary":false,"text":[{"text":"           || {","highlight_start":13,"highlight_end":14}],"label":"inferred to be a `FnMut` closure","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"`FnMut` closures only have access to their captured variables while they are executing...","code":null,"level":"note","spans":[],"children":[],"rendered":null},{"message":"...therefore, they cannot allow references to captured variables to escape","code":null,"level":"note","spans":[],"children":[],"rendered":null}],"rendered":"error: captured variable cannot escape `FnMut` closure body\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:294:16\n   |\nLL |              || {\n   |               - inferred to be a `FnMut` closure\nLL | /                || { //[mir]~ ERROR captured variable cannot escape `FnMut` closure body\nLL | |                    let y = &mut x;\nLL | |                    &mut x; //[ast]~ ERROR cannot borrow `**x` as mutable more than once at a time\nLL | |                    //[mir]~^ ERROR cannot borrow `x` as mutable more than once at a time\nLL | |                    *y = 1;\nLL | |                    drop(y);\nLL | |                 }\n   | |_________________^ returns a closure that contains a reference to a captured variable, which then escapes the closure body\n   |\n   = note: `FnMut` closures only have access to their captured variables while they are executing...\n   = note: ...therefore, they cannot allow references to captured variables to escape\n\n"}
[01:13:10] {"message":"cannot use `f.x` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":587,"byte_end":588,"line_start":42,"line_end":42,"column_start":17,"column_end":18,"is_primary":false,"text":[{"text":"        let x = f.x();","highlight_start":17,"highlight_end":18}],"label":"borrow of `f` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":602,"byte_end":605,"line_start":43,"line_end":43,"column_start":9,"column_end":12,"is_primary":true,"text":[{"text":"        f.x; //[ast]~ ERROR cannot use `f.x` because it was mutably borrowed","highlight_start":9,"highlight_end":12}],"label":"use of borrowed `f`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":757,"byte_end":758,"line_start":45,"line_end":45,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `f.x` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:43:9\n   |\nLL |         let x = f.x();\n   |                 - borrow of `f` occurs here\nLL |         f.x; //[ast]~ ERROR cannot use `f.x` because it was mutably borrowed\n   |         ^^^ use of borrowed `f`\nLL |         //[mir]~^ ERROR cannot use `f.x` because it was mutably borrowed\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `g.0` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":859,"byte_end":860,"line_start":50,"line_end":50,"column_start":17,"column_end":18,"is_primary":false,"text":[{"text":"        let x = g.x();","highlight_start":17,"highlight_end":18}],"label":"borrow of `g` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":874,"byte_end":877,"line_start":51,"line_end":51,"column_start":9,"column_end":12,"is_primary":true,"text":[{"text":"        g.0; //[ast]~ ERROR cannot use `g.0` because it was mutably borrowed","highlight_start":9,"highlight_end":12}],"label":"use of borrowed `g`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":1034,"byte_end":1035,"line_start":53,"line_end":53,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `g.0` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:51:9\n   |\nLL |         let x = g.x();\n   |                 - borrow of `g` occurs here\nLL |         g.0; //[ast]~ ERROR cannot use `g.0` because it was mutably borrowed\n   |         ^^^ use of borrowed `g`\nLL |              //[mir]~^ ERROR cannot use `g.0` because it was mutably borrowed\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `h.0` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":1130,"byte_end":1138,"line_start":58,"line_end":58,"column_start":17,"column_end":25,"is_primary":false,"text":[{"text":"        let x = &mut h.0;","highlight_start":17,"highlight_end":25}],"label":"borrow of `h.0` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":1148,"byte_end":1151,"line_start":59,"line_end":59,"column_start":9,"column_end":12,"is_primary":true,"text":[{"text":"        h.0; //[ast]~ ERROR cannot use `h.0` because it was mutably borrowed","highlight_start":9,"highlight_end":12}],"label":"use of borrowed `h.0`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":1308,"byte_end":1309,"line_start":61,"line_end":61,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `h.0` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:59:9\n   |\nLL |         let x = &mut h.0;\n   |                 -------- borrow of `h.0` occurs here\nLL |         h.0; //[ast]~ ERROR cannot use `h.0` because it was mutably borrowed\n   |         ^^^ use of borrowed `h.0`\nLL |              //[mir]~^ ERROR cannot use `h.0` because it was mutably borrowed\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `e.0` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":1404,"byte_end":1405,"line_start":66,"line_end":66,"column_start":17,"column_end":18,"is_primary":false,"text":[{"text":"        let x = e.x();","highlight_start":17,"highlight_end":18}],"label":"borrow of `e` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":1448,"byte_end":1453,"line_start":68,"line_end":68,"column_start":20,"column_end":25,"is_primary":true,"text":[{"text":"            Baz::X(value) => value","highlight_start":20,"highlight_end":25}],"label":"use of borrowed `e`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":1643,"byte_end":1644,"line_start":72,"line_end":72,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `e.0` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:68:20\n   |\nLL |         let x = e.x();\n   |                 - borrow of `e` occurs here\nLL |         match e {\nLL |             Baz::X(value) => value\n   |                    ^^^^^ use of borrowed `e`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `u.a` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":1748,"byte_end":1756,"line_start":77,"line_end":77,"column_start":17,"column_end":25,"is_primary":false,"text":[{"text":"        let x = &mut u.a;","highlight_start":17,"highlight_end":25}],"label":"borrow of `u.a` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":1766,"byte_end":1769,"line_start":78,"line_end":78,"column_start":9,"column_end":12,"is_primary":true,"text":[{"text":"        u.a; //[ast]~ ERROR cannot use `u.a` because it was mutably borrowed","highlight_start":9,"highlight_end":12}],"label":"use of borrowed `u.a`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":1926,"byte_end":1927,"line_start":80,"line_end":80,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `u.a` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:78:9\n   |\nLL |         let x = &mut u.a;\n   |                 -------- borrow of `u.a` occurs here\nLL |         u.a; //[ast]~ ERROR cannot use `u.a` because it was mutably borrowed\n   |         ^^^ use of borrowed `u.a`\nLL |              //[mir]~^ ERROR cannot use `u.a` because it was mutably borrowed\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `f.x` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2038,"byte_end":2039,"line_start":85,"line_end":85,"column_start":17,"column_end":18,"is_primary":false,"text":[{"text":"        let x = f.x();","highlight_start":17,"highlight_end":18}],"label":"borrow of `*f` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2053,"byte_end":2056,"line_start":86,"line_end":86,"column_start":9,"column_end":12,"is_primary":true,"text":[{"text":"        f.x; //[ast]~ ERROR cannot use `f.x` because it was mutably borrowed","highlight_start":9,"highlight_end":12}],"label":"use of borrowed `*f`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2213,"byte_end":2214,"line_start":88,"line_end":88,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `f.x` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:86:9\n   |\nLL |         let x = f.x();\n   |                 - borrow of `*f` occurs here\nLL |         f.x; //[ast]~ ERROR cannot use `f.x` because it was mutably borrowed\n   |         ^^^ use of borrowed `*f`\nLL |              //[mir]~^ ERROR cannot use `f.x` because it was mutably borrowed\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `g.0` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2325,"byte_end":2326,"line_start":93,"line_end":93,"column_start":17,"column_end":18,"is_primary":false,"text":[{"text":"        let x = g.x();","highlight_start":17,"highlight_end":18}],"label":"borrow of `*g` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2340,"byte_end":2343,"line_start":94,"line_end":94,"column_start":9,"column_end":12,"is_primary":true,"text":[{"text":"        g.0; //[ast]~ ERROR cannot use `g.0` because it was mutably borrowed","highlight_start":9,"highlight_end":12}],"label":"use of borrowed `*g`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2500,"byte_end":2501,"line_start":96,"line_end":96,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `g.0` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:94:9\n   |\nLL |         let x = g.x();\n   |                 - borrow of `*g` occurs here\nLL |         g.0; //[ast]~ ERROR cannot use `g.0` because it was mutably borrowed\n   |         ^^^ use of borrowed `*g`\nLL |              //[mir]~^ ERROR cannot use `g.0` because it was mutably borrowed\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `h.0` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2606,"byte_end":2614,"line_start":101,"line_end":101,"column_start":17,"column_end":25,"is_primary":false,"text":[{"text":"        let x = &mut h.0;","highlight_start":17,"highlight_end":25}],"label":"borrow of `h.0` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2624,"byte_end":2627,"line_start":102,"line_end":102,"column_start":9,"column_end":12,"is_primary":true,"text":[{"text":"        h.0; //[ast]~ ERROR cannot use `h.0` because it was mutably borrowed","highlight_start":9,"highlight_end":12}],"label":"use of borrowed `h.0`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2784,"byte_end":2785,"line_start":104,"line_end":104,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `h.0` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:102:9\n   |\nLL |         let x = &mut h.0;\n   |                 -------- borrow of `h.0` occurs here\nLL |         h.0; //[ast]~ ERROR cannot use `h.0` because it was mutably borrowed\n   |         ^^^ use of borrowed `h.0`\nLL |              //[mir]~^ ERROR cannot use `h.0` because it was mutably borrowed\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `e.0` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2890,"byte_end":2891,"line_start":109,"line_end":109,"column_start":17,"column_end":18,"is_primary":false,"text":[{"text":"        let x = e.x();","highlight_start":17,"highlight_end":18}],"label":"borrow of `*e` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":2935,"byte_end":2940,"line_start":111,"line_end":111,"column_start":20,"column_end":25,"is_primary":true,"text":[{"text":"            Baz::X(value) => value","highlight_start":20,"highlight_end":25}],"label":"use of borrowed `*e`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":3130,"byte_end":3131,"line_start":115,"line_end":115,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `e.0` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:111:20\n   |\nLL |         let x = e.x();\n   |                 - borrow of `*e` occurs here\nLL |         match *e {\nLL |             Baz::X(value) => value\n   |                    ^^^^^ use of borrowed `*e`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `u.a` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":3245,"byte_end":3253,"line_start":120,"line_end":120,"column_start":17,"column_end":25,"is_primary":false,"text":[{"text":"        let x = &mut u.a;","highlight_start":17,"highlight_end":25}],"label":"borrow of `u.a` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":3263,"byte_end":3266,"line_start":121,"line_end":121,"column_start":9,"column_end":12,"is_primary":true,"text":[{"text":"        u.a; //[ast]~ ERROR cannot use `u.a` because it was mutably borrowed","highlight_start":9,"highlight_end":12}],"label":"use of borrowed `u.a`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":3423,"byte_end":3424,"line_start":123,"line_end":123,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `u.a` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:121:9\n   |\nLL |         let x = &mut u.a;\n   |                 -------- borrow of `u.a` occurs here\nLL |         u.a; //[ast]~ ERROR cannot use `u.a` because it was mutably borrowed\n   |         ^^^ use of borrowed `u.a`\nLL |              //[mir]~^ ERROR cannot use `u.a` because it was mutably borrowed\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `v[..]` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":3531,"byte_end":3537,"line_start":128,"line_end":128,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"borrow of `v` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":3571,"byte_end":3572,"line_start":130,"line_end":130,"column_start":15,"column_end":16,"is_primary":true,"text":[{"text":"            &[x, _, .., _, _] => println!(\"{}\", x),","highlight_start":15,"highlight_end":16}],"label":"use of borrowed `v`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4760,"byte_end":4761,"line_start":153,"line_end":153,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `v[..]` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:130:15\n   |\nLL |         let x = &mut v;\n   |                 ------ borrow of `v` occurs here\nLL |         match v {\nLL |             &[x, _, .., _, _] => println!(\"{}\", x),\n   |               ^ use of borrowed `v`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `v[..]` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":3531,"byte_end":3537,"line_start":128,"line_end":128,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"borrow of `v` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":3876,"byte_end":3877,"line_start":136,"line_end":136,"column_start":18,"column_end":19,"is_primary":true,"text":[{"text":"            &[_, x, .., _, _] => println!(\"{}\", x),","highlight_start":18,"highlight_end":19}],"label":"use of borrowed `v`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4760,"byte_end":4761,"line_start":153,"line_end":153,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `v[..]` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:136:18\n   |\nLL |         let x = &mut v;\n   |                 ------ borrow of `v` occurs here\n...\nLL |             &[_, x, .., _, _] => println!(\"{}\", x),\n   |                  ^ use of borrowed `v`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `v[..]` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":3531,"byte_end":3537,"line_start":128,"line_end":128,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"borrow of `v` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4185,"byte_end":4186,"line_start":142,"line_end":142,"column_start":25,"column_end":26,"is_primary":true,"text":[{"text":"            &[_, _, .., x, _] => println!(\"{}\", x),","highlight_start":25,"highlight_end":26}],"label":"use of borrowed `v`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4760,"byte_end":4761,"line_start":153,"line_end":153,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `v[..]` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:142:25\n   |\nLL |         let x = &mut v;\n   |                 ------ borrow of `v` occurs here\n...\nLL |             &[_, _, .., x, _] => println!(\"{}\", x),\n   |                         ^ use of borrowed `v`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `v[..]` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":3531,"byte_end":3537,"line_start":128,"line_end":128,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"borrow of `v` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4490,"byte_end":4491,"line_start":148,"line_end":148,"column_start":28,"column_end":29,"is_primary":true,"text":[{"text":"            &[_, _, .., _, x] => println!(\"{}\", x),","highlight_start":28,"highlight_end":29}],"label":"use of borrowed `v`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4760,"byte_end":4761,"line_start":153,"line_end":153,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `v[..]` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:148:28\n   |\nLL |         let x = &mut v;\n   |                 ------ borrow of `v` occurs here\n...\nLL |             &[_, _, .., _, x] => println!(\"{}\", x),\n   |                            ^ use of borrowed `v`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `v[..]` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4847,"byte_end":4853,"line_start":158,"line_end":158,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"borrow of `v` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4887,"byte_end":4888,"line_start":160,"line_end":160,"column_start":15,"column_end":16,"is_primary":true,"text":[{"text":"            &[x..] => println!(\"{:?}\", x),","highlight_start":15,"highlight_end":16}],"label":"use of borrowed `v`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":5988,"byte_end":5989,"line_start":183,"line_end":183,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `v[..]` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:160:15\n   |\nLL |         let x = &mut v;\n   |                 ------ borrow of `v` occurs here\nLL |         match v {\nLL |             &[x..] => println!(\"{:?}\", x),\n   |               ^ use of borrowed `v`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `v[..]` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4847,"byte_end":4853,"line_start":158,"line_end":158,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"borrow of `v` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":5167,"byte_end":5168,"line_start":166,"line_end":166,"column_start":18,"column_end":19,"is_primary":true,"text":[{"text":"            &[_, x..] => println!(\"{:?}\", x),","highlight_start":18,"highlight_end":19}],"label":"use of borrowed `v`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":5988,"byte_end":5989,"line_start":183,"line_end":183,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `v[..]` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:166:18\n   |\nLL |         let x = &mut v;\n   |                 ------ borrow of `v` occurs here\n...\nLL |             &[_, x..] => println!(\"{:?}\", x),\n   |                  ^ use of borrowed `v`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `v[..]` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4847,"byte_end":4853,"line_start":158,"line_end":158,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"borrow of `v` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":5444,"byte_end":5445,"line_start":172,"line_end":172,"column_start":15,"column_end":16,"is_primary":true,"text":[{"text":"            &[x.., _] => println!(\"{:?}\", x),","highlight_start":15,"highlight_end":16}],"label":"use of borrowed `v`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":5988,"byte_end":5989,"line_start":183,"line_end":183,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `v[..]` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:172:15\n   |\nLL |         let x = &mut v;\n   |                 ------ borrow of `v` occurs here\n...\nLL |             &[x.., _] => println!(\"{:?}\", x),\n   |               ^ use of borrowed `v`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `v[..]` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":4847,"byte_end":4853,"line_start":158,"line_end":158,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"borrow of `v` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":5727,"byte_end":5728,"line_start":178,"line_end":178,"column_start":18,"column_end":19,"is_primary":true,"text":[{"text":"            &[_, x.., _] => println!(\"{:?}\", x),","highlight_start":18,"highlight_end":19}],"label":"use of borrowed `v`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":5988,"byte_end":5989,"line_start":183,"line_end":183,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `v[..]` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:178:18\n   |\nLL |         let x = &mut v;\n   |                 ------ borrow of `v` occurs here\n...\nLL |             &[_, x.., _] => println!(\"{:?}\", x),\n   |                  ^ use of borrowed `v`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `e` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":6113,"byte_end":6119,"line_start":190,"line_end":190,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut e;","highlight_start":17,"highlight_end":23}],"label":"borrow of `e` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":6151,"byte_end":6163,"line_start":192,"line_end":192,"column_start":13,"column_end":25,"is_primary":true,"text":[{"text":"            E::A(ref ax) =>","highlight_start":13,"highlight_end":25}],"label":"use of borrowed `e`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":6811,"byte_end":6812,"line_start":202,"line_end":202,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `e` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:192:13\n   |\nLL |         let x = &mut e;\n   |                 ------ borrow of `e` occurs here\nLL |         match e {\nLL |             E::A(ref ax) =>\n   |             ^^^^^^^^^^^^ use of borrowed `e`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot borrow `e.0` as immutable because it is also borrowed as mutable","code":{"code":"E0502","explanation":"\nThis error indicates that you are trying to borrow a variable as mutable when it\nhas already been borrowed as immutable.\n\nExample of erroneous code:\n\n```compile_fail,E0502\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    let ref y = a; // a is borrowed as immutable.\n    bar(a); // error: cannot borrow `*a` as mutable because `a` is also borrowed\n            //        as immutable\n}\n```\n\nTo fix this error, ensure that you don't have any other references to the\nvariable before trying to access it mutably:\n\n```\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    bar(a);\n    let ref y = a; // ok!\n}\n```\n\nFor more information on the rust ownership system, take a look at\nhttps://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html.\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":6156,"byte_end":6162,"line_start":192,"line_end":192,"column_start":18,"column_end":24,"is_primary":true,"text":[{"text":"            E::A(ref ax) =>","highlight_start":18,"highlight_end":24}],"label":"immutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":6113,"byte_end":6119,"line_start":190,"line_end":190,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut e;","highlight_start":17,"highlight_end":23}],"label":"mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":6811,"byte_end":6812,"line_start":202,"line_end":202,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"mutable borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0502]: cannot borrow `e.0` as immutable because it is also borrowed as mutable\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:192:18\n   |\nLL |         let x = &mut e;\n   |                 ------ mutable borrow occurs here\nLL |         match e {\nLL |             E::A(ref ax) =>\n   |                  ^^^^^^ immutable borrow occurs here\n...\nLL |         drop(x);\n   |              - mutable borrow later used here\n\n"}
[01:13:10] {"message":"cannot borrow `e.0` as immutable because it is also borrowed as mutable","code":{"code":"E0502","explanation":"\nThis error indicates that you are trying to borrow a variable as mutable when it\nhas already been borrowed as immutable.\n\nExample of erroneous code:\n\n```compile_fail,E0502\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    let ref y = a; // a is borrowed as immutable.\n    bar(a); // error: cannot borrow `*a` as mutable because `a` is also borrowed\n            //        as immutable\n}\n```\n\nTo fix this error, ensure that you don't have any other references to the\nvariable before trying to access it mutably:\n\n```\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    bar(a);\n    let ref y = a; // ok!\n}\n```\n\nFor more information on the rust ownership system, take a look at\nhttps://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html.\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":6522,"byte_end":6528,"line_start":197,"line_end":197,"column_start":23,"column_end":29,"is_primary":true,"text":[{"text":"            E::B { x: ref bx } =>","highlight_start":23,"highlight_end":29}],"label":"immutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":6113,"byte_end":6119,"line_start":190,"line_end":190,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut e;","highlight_start":17,"highlight_end":23}],"label":"mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":6811,"byte_end":6812,"line_start":202,"line_end":202,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"mutable borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0502]: cannot borrow `e.0` as immutable because it is also borrowed as mutable\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:197:23\n   |\nLL |         let x = &mut e;\n   |                 ------ mutable borrow occurs here\n...\nLL |             E::B { x: ref bx } =>\n   |                       ^^^^^^ immutable borrow occurs here\n...\nLL |         drop(x);\n   |              - mutable borrow later used here\n\n"}
[01:13:10] {"message":"cannot borrow `s.y.0` as immutable because it is also borrowed as mutable","code":{"code":"E0502","explanation":"\nThis error indicates that you are trying to borrow a variable as mutable when it\nhas already been borrowed as immutable.\n\nExample of erroneous code:\n\n```compile_fail,E0502\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    let ref y = a; // a is borrowed as immutable.\n    bar(a); // error: cannot borrow `*a` as mutable because `a` is also borrowed\n            //        as immutable\n}\n```\n\nTo fix this error, ensure that you don't have any other references to the\nvariable before trying to access it mutably:\n\n```\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    bar(a);\n    let ref y = a; // ok!\n}\n```\n\nFor more information on the rust ownership system, take a look at\nhttps://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html.\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":7053,"byte_end":7059,"line_start":211,"line_end":211,"column_start":22,"column_end":28,"is_primary":true,"text":[{"text":"            S  { y: (ref y0, _), .. } =>","highlight_start":22,"highlight_end":28}],"label":"immutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":7006,"byte_end":7012,"line_start":209,"line_end":209,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut s;","highlight_start":17,"highlight_end":23}],"label":"mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":7763,"byte_end":7764,"line_start":224,"line_end":224,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"mutable borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0502]: cannot borrow `s.y.0` as immutable because it is also borrowed as mutable\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:211:22\n   |\nLL |         let x = &mut s;\n   |                 ------ mutable borrow occurs here\nLL |         match s {\nLL |             S  { y: (ref y0, _), .. } =>\n   |                      ^^^^^^ immutable borrow occurs here\n...\nLL |         drop(x);\n   |              - mutable borrow later used here\n\n"}
[01:13:10] {"message":"cannot borrow `s.x.y` as immutable because it is also borrowed as mutable","code":{"code":"E0502","explanation":"\nThis error indicates that you are trying to borrow a variable as mutable when it\nhas already been borrowed as immutable.\n\nExample of erroneous code:\n\n```compile_fail,E0502\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    let ref y = a; // a is borrowed as immutable.\n    bar(a); // error: cannot borrow `*a` as mutable because `a` is also borrowed\n            //        as immutable\n}\n```\n\nTo fix this error, ensure that you don't have any other references to the\nvariable before trying to access it mutably:\n\n```\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    bar(a);\n    let ref y = a; // ok!\n}\n```\n\nFor more information on the rust ownership system, take a look at\nhttps://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html.\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":7423,"byte_end":7429,"line_start":218,"line_end":218,"column_start":28,"column_end":34,"is_primary":true,"text":[{"text":"            S  { x: F { y: ref x0, .. }, .. } =>","highlight_start":28,"highlight_end":34}],"label":"immutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":7006,"byte_end":7012,"line_start":209,"line_end":209,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut s;","highlight_start":17,"highlight_end":23}],"label":"mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":7763,"byte_end":7764,"line_start":224,"line_end":224,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"mutable borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0502]: cannot borrow `s.x.y` as immutable because it is also borrowed as mutable\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:218:28\n   |\nLL |         let x = &mut s;\n   |                 ------ mutable borrow occurs here\n...\nLL |             S  { x: F { y: ref x0, .. }, .. } =>\n   |                            ^^^^^^ immutable borrow occurs here\n...\nLL |         drop(x);\n   |              - mutable borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `*v` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":8833,"byte_end":8839,"line_start":260,"line_end":260,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"borrow of `v` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":8849,"byte_end":8853,"line_start":261,"line_end":261,"column_start":9,"column_end":13,"is_primary":true,"text":[{"text":"        v[0].y;","highlight_start":9,"highlight_end":13}],"label":"use of borrowed `v`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":9096,"byte_end":9097,"line_start":265,"line_end":265,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `*v` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:261:9\n   |\nLL |         let x = &mut v;\n   |                 ------ borrow of `v` occurs here\nLL |         v[0].y;\n   |         ^^^^ use of borrowed `v`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot use `v[_].y` because it was mutably borrowed","code":{"code":"E0503","explanation":"\nA value was used after it was mutably borrowed.\n\nExample of erroneous code:\n\n```compile_fail,E0503\nfn main() {\n    let mut value = 3;\n    // Create a mutable borrow of `value`. This borrow\n    // lives until the end of this function.\n    let _borrow = &mut value;\n    let _sum = value + 1; // error: cannot use `value` because\n                          //        it was mutably borrowed\n}\n```\n\nIn this example, `value` is mutably borrowed by `borrow` and cannot be\nused to calculate `sum`. This is not possible because this would violate\nRust's mutability rules.\n\nYou can fix this error by limiting the scope of the borrow:\n\n```\nfn main() {\n    let mut value = 3;\n    // By creating a new block, you can limit the scope\n    // of the reference.\n    {\n        let _borrow = &mut value; // Use `_borrow` inside this block.\n    }\n    // The block has ended and with it the borrow.\n    // You can now use `value` again.\n    let _sum = value + 1;\n}\n```\n\nOr by cloning `value` before borrowing it:\n\n```\nfn main() {\n    let mut value = 3;\n    // We clone `value`, creating a copy.\n    let value_cloned = value.clone();\n    // The mutable borrow is a reference to `value` and\n    // not to `value_cloned`...\n    let _borrow = &mut value;\n    // ... which means we can still use `value_cloned`,\n    let _sum = value_cloned + 1;\n    // even though the borrow only ends here.\n}\n```\n\nYou can find more information about borrowing in the rust-book:\nhttp://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":8833,"byte_end":8839,"line_start":260,"line_end":260,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"borrow of `v` occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":8849,"byte_end":8855,"line_start":261,"line_end":261,"column_start":9,"column_end":15,"is_primary":true,"text":[{"text":"        v[0].y;","highlight_start":9,"highlight_end":15}],"label":"use of borrowed `v`","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":9096,"byte_end":9097,"line_start":265,"line_end":265,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0503]: cannot use `v[_].y` because it was mutably borrowed\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:261:9\n   |\nLL |         let x = &mut v;\n   |                 ------ borrow of `v` occurs here\nLL |         v[0].y;\n   |         ^^^^^^ use of borrowed `v`\n...\nLL |         drop(x);\n   |              - borrow later used here\n\n"}
[01:13:10] {"message":"cannot borrow `v[..].x` as immutable because it is also borrowed as mutable","code":{"code":"E0502","explanation":"\nThis error indicates that you are trying to borrow a variable as mutable when it\nhas already been borrowed as immutable.\n\nExample of erroneous code:\n\n```compile_fail,E0502\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    let ref y = a; // a is borrowed as immutable.\n    bar(a); // error: cannot borrow `*a` as mutable because `a` is also borrowed\n            //        as immutable\n}\n```\n\nTo fix this error, ensure that you don't have any other references to the\nvariable before trying to access it mutably:\n\n```\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    bar(a);\n    let ref y = a; // ok!\n}\n```\n\nFor more information on the rust ownership system, take a look at\nhttps://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html.\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":9296,"byte_end":9302,"line_start":273,"line_end":273,"column_start":24,"column_end":30,"is_primary":true,"text":[{"text":"            &[_, F {x: ref xf, ..}] => println!(\"{}\", xf),","highlight_start":24,"highlight_end":30}],"label":"immutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":9247,"byte_end":9253,"line_start":271,"line_end":271,"column_start":17,"column_end":23,"is_primary":false,"text":[{"text":"        let x = &mut v;","highlight_start":17,"highlight_end":23}],"label":"mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":9529,"byte_end":9530,"line_start":278,"line_end":278,"column_start":14,"column_end":15,"is_primary":false,"text":[{"text":"        drop(x);","highlight_start":14,"highlight_end":15}],"label":"mutable borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0502]: cannot borrow `v[..].x` as immutable because it is also borrowed as mutable\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:273:24\n   |\nLL |         let x = &mut v;\n   |                 ------ mutable borrow occurs here\nLL |         match v {\nLL |             &[_, F {x: ref xf, ..}] => println!(\"{}\", xf),\n   |                        ^^^^^^ immutable borrow occurs here\n...\nLL |         drop(x);\n   |              - mutable borrow later used here\n\n"}
[01:13:10] {"message":"cannot borrow `*block.current` as immutable because it is also borrowed as mutable","code":{"code":"E0502","explanation":"\nThis error indicates that you are trying to borrow a variable as mutable when it\nhas already been borrowed as immutable.\n\nExample of erroneous code:\n\n```compile_fail,E0502\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    let ref y = a; // a is borrowed as immutable.\n    bar(a); // error: cannot borrow `*a` as mutable because `a` is also borrowed\n            //        as immutable\n}\n```\n\nTo fix this error, ensure that you don't have any other references to the\nvariable before trying to access it mutably:\n\n```\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    bar(a);\n    let ref y = a; // ok!\n}\n```\n\nFor more information on the rust ownership system, take a look at\nhttps://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html.\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":8007,"byte_end":8022,"line_start":235,"line_end":235,"column_start":29,"column_end":44,"is_primary":true,"text":[{"text":"            let p: &'a u8 = &*block.current;","highlight_start":29,"highlight_end":44}],"label":"immutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":7967,"byte_end":7977,"line_start":234,"line_end":234,"column_start":21,"column_end":31,"is_primary":false,"text":[{"text":"            let x = &mut block;","highlight_start":21,"highlight_end":31}],"label":"mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":8212,"byte_end":8213,"line_start":238,"line_end":238,"column_start":18,"column_end":19,"is_primary":false,"text":[{"text":"            drop(x);","highlight_start":18,"highlight_end":19}],"label":"mutable borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0502]: cannot borrow `*block.current` as immutable because it is also borrowed as mutable\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:235:29\n   |\nLL |             let x = &mut block;\n   |                     ---------- mutable borrow occurs here\nLL |             let p: &'a u8 = &*block.current;\n   |                             ^^^^^^^^^^^^^^^ immutable borrow occurs here\n...\nLL |             drop(x);\n   |                  - mutable borrow later used here\n\n"}
[01:13:10] {"message":"cannot borrow `*block.current` as immutable because it is also borrowed as mutable","code":{"code":"E0502","explanation":"\nThis error indicates that you are trying to borrow a variable as mutable when it\nhas already been borrowed as immutable.\n\nExample of erroneous code:\n\n```compile_fail,E0502\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    let ref y = a; // a is borrowed as immutable.\n    bar(a); // error: cannot borrow `*a` as mutable because `a` is also borrowed\n            //        as immutable\n}\n```\n\nTo fix this error, ensure that you don't have any other references to the\nvariable before trying to access it mutably:\n\n```\nfn bar(x: &mut i32) {}\nfn foo(a: &mut i32) {\n    bar(a);\n    let ref y = a; // ok!\n}\n```\n\nFor more information on the rust ownership system, take a look at\nhttps://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html.\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":8473,"byte_end":8491,"line_start":250,"line_end":250,"column_start":33,"column_end":51,"is_primary":true,"text":[{"text":"            let p : *const u8 = &*(*block).current;","highlight_start":33,"highlight_end":51}],"label":"immutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":8429,"byte_end":8439,"line_start":249,"line_end":249,"column_start":21,"column_end":31,"is_primary":false,"text":[{"text":"            let x = &mut block;","highlight_start":21,"highlight_end":31}],"label":"mutable borrow occurs here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":8681,"byte_end":8682,"line_start":253,"line_end":253,"column_start":18,"column_end":19,"is_primary":false,"text":[{"text":"            drop(x);","highlight_start":18,"highlight_end":19}],"label":"mutable borrow later used here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0502]: cannot borrow `*block.current` as immutable because it is also borrowed as mutable\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:250:33\n   |\nLL |             let x = &mut block;\n   |                     ---------- mutable borrow occurs here\nLL |             let p : *const u8 = &*(*block).current;\n   |                                 ^^^^^^^^^^^^^^^^^^ immutable borrow occurs here\n...\nLL |             drop(x);\n   |                  - mutable borrow later used here\n\n"}
[01:13:10] {"message":"use of moved value: `x`","code":{"code":"E0382","explanation":"\nThis error occurs when an attempt is made to use a variable after its contents\nhave been moved elsewhere. For example:\n\n```compile_fail,E0382\nstruct MyStruct { s: u32 }\n\nfn main() {\n    let mut x = MyStruct{ s: 5u32 };\n    let y = x;\n    x.s = 6;\n    println!(\"{}\", x.s);\n}\n```\n\nSince `MyStruct` is a type that is not marked `Copy`, the data gets moved out\nof `x` when we set `y`. This is fundamental to Rust's ownership system: outside\nof workarounds like `Rc`, a value cannot be owned by more than one variable.\n\nSometimes we don't need to move the value. Using a reference, we can let another\nfunction borrow the value without changing its ownership. In the example below,\nwe don't actually have to move our string to `calculate_length`, we can give it\na reference to it with `&` instead.\n\n```\nfn main() {\n    let s1 = String::from(\"hello\");\n\n    let len = calculate_length(&s1);\n\n    println!(\"The length of '{}' is {}.\", s1, len);\n}\n\nfn calculate_length(s: &String) -> usize {\n    s.len()\n}\n```\n\nA mutable reference can be created with `&mut`.\n\nSometimes we don't want a reference, but a duplicate. All types marked `Clone`\ncan be duplicated by calling `.clone()`. Subsequent changes to a clone do not\naffect the original variable.\n\nMost types in the standard library are marked `Clone`. The example below\ndemonstrates using `clone()` on a string. `s1` is first set to \"many\", and then\ncopied to `s2`. Then the first character of `s1` is removed, without affecting\n`s2`. \"any many\" is printed to the console.\n\n```\nfn main() {\n    let mut s1 = String::from(\"many\");\n    let s2 = s1.clone();\n    s1.remove(0);\n    println!(\"{} {}\", s1, s2);\n}\n```\n\nIf we control the definition of a type, we can implement `Clone` on it ourselves\nwith `#[derive(Clone)]`.\n\nSome types have no ownership semantics at all and are trivial to duplicate. An\nexample is `i32` and the other number types. We don't have to call `.clone()` to\nclone them, because they are marked `Copy` in addition to `Clone`.  Implicit\ncloning is more convenient in this case. We can mark our own types `Copy` if\nall their members also are marked `Copy`.\n\nIn the example below, we implement a `Point` type. Because it only stores two\nintegers, we opt-out of ownership semantics with `Copy`. Then we can\n`let p2 = p1` without `p1` being moved.\n\n```\n#[derive(Copy, Clone)]\nstruct Point { x: i32, y: i32 }\n\nfn main() {\n    let mut p1 = Point{ x: -1, y: 2 };\n    let p2 = p1;\n    p1.x = 1;\n    println!(\"p1: {}, {}\", p1.x, p1.y);\n    println!(\"p2: {}, {}\", p2.x, p2.y);\n}\n```\n\nAlternatively, if we don't control the struct's definition, or mutable shared\nownership is truly required, we can use `Rc` and `RefCell`:\n\n```\nuse std::cell::RefCell;\nuse std::rc::Rc;\n\nstruct MyStruct { s: u32 }\n\nfn main() {\n    let mut x = Rc::new(RefCell::new(MyStruct{ s: 5u32 }));\n    let y = x.clone();\n    x.borrow_mut().s = 6;\n    println!(\"{}\", x.borrow().s);\n}\n```\n\nWith this approach, x and y share ownership of the data via the `Rc` (reference\ncount type). `RefCell` essentially performs runtime borrow checking: ensuring\nthat at most one writer or multiple readers can access the data at any one time.\n\nIf you wish to learn more about ownership in Rust, start with the chapter in the\nBook:\n\nhttps://doc.rust-lang.org/book/ch04-00-understanding-ownership.html\n"},"level":"error","spans":[{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":10412,"byte_end":10413,"line_start":306,"line_end":306,"column_start":22,"column_end":23,"is_primary":false,"text":[{"text":"                drop(x);","highlight_start":22,"highlight_end":23}],"label":"value moved here","suggested_replacement":null,"suggestion_applicability":null,"expansion":null},{"file_name":"/checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs","byte_start":10437,"byte_end":10438,"line_start":307,"line_end":307,"column_start":22,"column_end":23,"is_primary":true,"text":[{"text":"                drop(x); //[ast]~ ERROR use of moved value: `x`","highlight_start":22,"highlight_end":23}],"label":"value used here after move","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"move occurs because `x` has type `std::vec::Vec<i32>`, which does not implement the `Copy` trait","code":null,"level":"note","spans":[],"children":[],"rendered":null}],"rendered":"error[E0382]: use of moved value: `x`\n  --> /checkout/src/test/ui/borrowck/borrowck-describe-lvalue.rs:307:22\n   |\nLL |                 drop(x);\n   |                      - value moved here\nLL |                 drop(x); //[ast]~ ERROR use of moved value: `x`\n   |                      ^ value used here after move\n   |\n   = note: move occurs because `x` has type `std::vec::Vec<i32>`, which does not implement the `Copy` trait\n\n"}
[01:13:10] {"message":"aborting due to 32 previous errors","code":null,"level":"error","spans":[],"children":[],"rendered":"error: aborting due to 32 previous errors\n\n"}
[01:13:10] {"message":"Some errors occurred: E0382, E0499, E0502, E0503.","code":null,"level":"","spans":[],"children":[],"rendered":"Some errors occurred: E0382, E0499, E0502, E0503.\n"}
[01:13:10] 
[01:13:10] ------------------------------------------
[01:13:10] 
[01:13:10] thread '[ui] ui/borrowck/borrowck-describe-lvalue.rs#mir' panicked at 'explicit panic', src/tools/compiletest/src/runtest.rs:3422:9
---
[01:13:10] 
[01:13:10] thread 'main' panicked at 'Some tests failed', src/tools/compiletest/src/main.rs:516:22
[01:13:10] 
[01:13:10] 
[01:13:10] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "--compile-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" "--run-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "--rustc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "--src-base" "/checkout/src/test/ui" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--mode" "ui" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/usr/lib/llvm-6.0/bin/FileCheck" "--host-rustcflags" "-Crpath -O -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target-rustcflags" "-Crpath -O -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python2.7" "--lldb-python" "/usr/bin/python2.7" "--gdb" "/usr/bin/gdb" "--quiet" "--llvm-version" "6.0.0\n" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--llvm-cxxflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
[01:13:10] 
[01:13:10] 
[01:13:10] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[01:13:10] Build completed unsuccessfully in 0:04:18
[01:13:10] Build completed unsuccessfully in 0:04:18
[01:13:10] make: *** [check] Error 1
[01:13:10] Makefile:48: recipe for target 'check' failed
2766044 ./obj
2766004 ./obj/build
2093520 ./obj/build/x86_64-unknown-linux-gnu
1371080 ./src
---
147104 ./obj/build/x86_64-unknown-linux-gnu/stage0-bootstrap-tools/x86_64-unknown-linux-gnu
147100 ./obj/build/x86_64-unknown-linux-gnu/stage0-bootstrap-tools/x86_64-unknown-linux-gnu/release
143588 ./obj/build/x86_64-unknown-linux-gnu/stage0-bootstrap-tools/x86_64-unknown-linux-gnu/release/deps
142560 ./obj/build/bootstrap/debug/incremental/bootstrap-2vehb6dba088a
142556 ./obj/build/bootstrap/debug/incremental/bootstrap-2vehb6dba088a/s-fasc1m2ar7-552fnu-h9pt7lk04bnw
138372 ./obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu
138368 ./obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release
135528 ./obj/build/x86_64-unknown-linux-gnu/stage0-rustc/x86_64-unknown-linux-gnu/release/deps
123640 ./src/llvm-project/llvm/test/CodeGen

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[eddyb]

@rust-timer build 24a40d8

[rust-timer]

Success: Queued 24a40d8 with parent 70a497a, comparison URL.

[rust-timer]

Finished benchmarking try commit 24a40d8

[eddyb]

You can remove this match, it's kind of pointless nowadays.

[tmandry]

done

[eddyb]

This is subtly incomplete, but pre-existing.
The non-downcast case should use .non_enum_variant() to get the variant, while downcasts should assert the ADT is an enum.

[tmandry]

done

[eddyb]

Wait, how do we print fields? Always by index? Or do they use some trickery to show the name of the field? Because if the latter, we can reuse that for downcasts too.

[eddyb]

Since we are going ahead with this, might as well switch to:

pub struct PlaceTy<'tcx> {
    pub ty: Ty<'tcx>,
    pub variant_index: Option<VariantIdx>,
}

[tmandry]

done

[eddyb]

Can you remove this?

[eddyb]

Unnecessary borrows in these two lines.

[eddyb]

This should be impossible.

[tmandry]

Updated, then rebased.

[eddyb]

r=me with this last comment addressed

[tmandry]

@bors r=eddyb

[bors]

📌 Commit 4122d22 has been approved by eddyb