Auto merge of #94934 - Lireer:const-prop-lint, r=oli-obk

Separate const prop lints from optimizations r? `@oli-obk` Separates lints and optimizations during const prop by moving the lints into their own file and checking them during post borrowck cleanup. Thanks to `@oli-obk` for mentoring me.
rust-lang · Mar 24, 2022 · 63b8f01 · 63b8f01
2 parents 4b133a7 + 440946a
commit 63b8f01
Show file tree

Hide file tree

Showing 30 changed files with 1,308 additions and 239 deletions.
diff --git a/compiler/rustc_mir_transform/src/const_prop.rs b/compiler/rustc_mir_transform/src/const_prop.rs
diff --git a/compiler/rustc_mir_transform/src/const_prop_lint.rs b/compiler/rustc_mir_transform/src/const_prop_lint.rs
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
@@ -49,6 +49,7 @@ pub mod cleanup_post_borrowck;
 mod const_debuginfo;
 mod const_goto;
 mod const_prop;
+mod const_prop_lint;
 mod coverage;
 mod deaggregator;
 mod deduplicate_blocks;
@@ -430,6 +431,7 @@ fn run_post_borrowck_cleanup_passes<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tc
         // `Deaggregator` is conceptually part of MIR building, some backends rely on it happening
         // and it can help optimizations.
         &deaggregator::Deaggregator,
+        &Lint(const_prop_lint::ConstProp),
     ];
 
     pm::run_passes(tcx, body, post_borrowck_cleanup);

diff --git a/src/test/codegen/consts.rs b/src/test/codegen/consts.rs
@@ -10,7 +10,7 @@
 // CHECK: @STATIC = {{.*}}, align 4
 
 // This checks the constants from inline_enum_const
-// CHECK: @alloc9 = {{.*}}, align 2
+// CHECK: @alloc12 = {{.*}}, align 2
 
 // This checks the constants from {low,high}_align_const, they share the same
 // constant, but the alignment differs, so the higher one should be used

diff --git a/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-impl.rs b/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-impl.rs
@@ -4,12 +4,12 @@ trait Foo {
     const BAR: u32;
 }
 
-const IMPL_REF_BAR: u32 = GlobalImplRef::BAR; //~ ERROR E0391
+const IMPL_REF_BAR: u32 = GlobalImplRef::BAR;
 
 struct GlobalImplRef;
 
 impl GlobalImplRef {
-    const BAR: u32 = IMPL_REF_BAR;
+    const BAR: u32 = IMPL_REF_BAR; //~ ERROR E0391
 }
 
 fn main() {}
diff --git a/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-impl.stderr b/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-impl.stderr
@@ -1,9 +1,15 @@
-error[E0391]: cycle detected when simplifying constant for the type system `IMPL_REF_BAR`
+error[E0391]: cycle detected when elaborating drops for `<impl at $DIR/issue-24949-assoc-const-static-recursion-impl.rs:11:1: 13:2>::BAR`
+  --> $DIR/issue-24949-assoc-const-static-recursion-impl.rs:12:5
+   |
+LL |     const BAR: u32 = IMPL_REF_BAR;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: ...which requires normalizing `IMPL_REF_BAR`...
+note: ...which requires simplifying constant for the type system `IMPL_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-impl.rs:7:1
    |
 LL | const IMPL_REF_BAR: u32 = GlobalImplRef::BAR;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
 note: ...which requires simplifying constant for the type system `IMPL_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-impl.rs:7:1
    |
@@ -35,8 +41,7 @@ note: ...which requires caching mir of `<impl at $DIR/issue-24949-assoc-const-st
    |
 LL |     const BAR: u32 = IMPL_REF_BAR;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: ...which requires normalizing `IMPL_REF_BAR`...
-   = note: ...which again requires simplifying constant for the type system `IMPL_REF_BAR`, completing the cycle
+   = note: ...which again requires elaborating drops for `<impl at $DIR/issue-24949-assoc-const-static-recursion-impl.rs:11:1: 13:2>::BAR`, completing the cycle
    = note: cycle used when running analysis passes on this crate
 
 error: aborting due to previous error

diff --git a/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait-default.rs b/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait-default.rs
@@ -5,10 +5,10 @@ trait Foo {
 }
 
 trait FooDefault {
-    const BAR: u32 = DEFAULT_REF_BAR;
+    const BAR: u32 = DEFAULT_REF_BAR; //~ ERROR E0391
 }
 
-const DEFAULT_REF_BAR: u32 = <GlobalDefaultRef>::BAR; //~ ERROR E0391
+const DEFAULT_REF_BAR: u32 = <GlobalDefaultRef>::BAR;
 
 struct GlobalDefaultRef;
 

diff --git a/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait-default.stderr b/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait-default.stderr
@@ -1,9 +1,15 @@
-error[E0391]: cycle detected when simplifying constant for the type system `DEFAULT_REF_BAR`
+error[E0391]: cycle detected when elaborating drops for `FooDefault::BAR`
+  --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:8:5
+   |
+LL |     const BAR: u32 = DEFAULT_REF_BAR;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: ...which requires normalizing `DEFAULT_REF_BAR`...
+note: ...which requires simplifying constant for the type system `DEFAULT_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:11:1
    |
 LL | const DEFAULT_REF_BAR: u32 = <GlobalDefaultRef>::BAR;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
 note: ...which requires simplifying constant for the type system `DEFAULT_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait-default.rs:11:1
    |
@@ -35,8 +41,7 @@ note: ...which requires caching mir of `FooDefault::BAR` for CTFE...
    |
 LL |     const BAR: u32 = DEFAULT_REF_BAR;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: ...which requires normalizing `DEFAULT_REF_BAR`...
-   = note: ...which again requires simplifying constant for the type system `DEFAULT_REF_BAR`, completing the cycle
+   = note: ...which again requires elaborating drops for `FooDefault::BAR`, completing the cycle
    = note: cycle used when running analysis passes on this crate
 
 error: aborting due to previous error

diff --git a/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait.rs b/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait.rs
@@ -4,12 +4,12 @@ trait Foo {
     const BAR: u32;
 }
 
-const TRAIT_REF_BAR: u32 = <GlobalTraitRef>::BAR; //~ ERROR E0391
+const TRAIT_REF_BAR: u32 = <GlobalTraitRef>::BAR;
 
 struct GlobalTraitRef;
 
 impl Foo for GlobalTraitRef {
-    const BAR: u32 = TRAIT_REF_BAR;
+    const BAR: u32 = TRAIT_REF_BAR; //~ ERROR E0391
 }
 
 fn main() {}
diff --git a/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait.stderr b/src/test/ui/associated-consts/issue-24949-assoc-const-static-recursion-trait.stderr
@@ -1,9 +1,15 @@
-error[E0391]: cycle detected when simplifying constant for the type system `TRAIT_REF_BAR`
+error[E0391]: cycle detected when elaborating drops for `<impl at $DIR/issue-24949-assoc-const-static-recursion-trait.rs:11:1: 13:2>::BAR`
+  --> $DIR/issue-24949-assoc-const-static-recursion-trait.rs:12:5
+   |
+LL |     const BAR: u32 = TRAIT_REF_BAR;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: ...which requires normalizing `TRAIT_REF_BAR`...
+note: ...which requires simplifying constant for the type system `TRAIT_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait.rs:7:1
    |
 LL | const TRAIT_REF_BAR: u32 = <GlobalTraitRef>::BAR;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
 note: ...which requires simplifying constant for the type system `TRAIT_REF_BAR`...
   --> $DIR/issue-24949-assoc-const-static-recursion-trait.rs:7:1
    |
@@ -35,8 +41,7 @@ note: ...which requires caching mir of `<impl at $DIR/issue-24949-assoc-const-st
    |
 LL |     const BAR: u32 = TRAIT_REF_BAR;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: ...which requires normalizing `TRAIT_REF_BAR`...
-   = note: ...which again requires simplifying constant for the type system `TRAIT_REF_BAR`, completing the cycle
+   = note: ...which again requires elaborating drops for `<impl at $DIR/issue-24949-assoc-const-static-recursion-trait.rs:11:1: 13:2>::BAR`, completing the cycle
    = note: cycle used when running analysis passes on this crate
 
 error: aborting due to previous error

diff --git a/src/test/ui/const_prop/inline_spans.rs b/src/test/ui/const_prop/inline_spans.rs
@@ -1,18 +1,15 @@
-// build-fail
+// build-pass
 // compile-flags: -Zmir-opt-level=3
+// Overflow can't be detected by const prop
+// could only be detected after optimizations
 
 #![deny(warnings)]
 
 fn main() {
     let _ = add(u8::MAX, 1);
-    //~^ NOTE in this expansion of inlined source
-    //~| NOTE in this expansion of inlined source
 }
 
 #[inline(always)]
 fn add(x: u8, y: u8) -> u8 {
     x + y
-    //~^ ERROR this arithmetic operation will overflow
-    //~| NOTE attempt to compute `u8::MAX + 1_u8`, which would overflow
-    //~| NOTE `#[deny(arithmetic_overflow)]` on by default
 }
diff --git a/src/test/ui/const_prop/inline_spans.stderr b/src/test/ui/const_prop/inline_spans.stderr
diff --git a/src/test/ui/consts/const-eval/const-eval-query-stack.stderr b/src/test/ui/consts/const-eval/const-eval-query-stack.stderr
@@ -21,6 +21,7 @@ LL |     let x: &'static i32 = &X;
    |                            ^ referenced constant has errors
 query stack during panic:
 #0 [try_normalize_mir_const_after_erasing_regions] normalizing `main::promoted[1]`
-#1 [optimized_mir] optimizing MIR for `main`
-#2 [collect_and_partition_mono_items] collect_and_partition_mono_items
+#1 [mir_drops_elaborated_and_const_checked] elaborating drops for `main`
+#2 [optimized_mir] optimizing MIR for `main`
+#3 [collect_and_partition_mono_items] collect_and_partition_mono_items
 end of query stack
diff --git a/src/test/ui/consts/const-eval/issue-49296.stderr b/src/test/ui/consts/const-eval/issue-49296.stderr
@@ -2,7 +2,7 @@ error[E0080]: evaluation of constant value failed
   --> $DIR/issue-49296.rs:9:16
    |
 LL | const X: u64 = *wat(42);
-   |                ^^^^^^^^ pointer to alloc2 was dereferenced after this allocation got freed
+   |                ^^^^^^^^ pointer to alloc3 was dereferenced after this allocation got freed
 
 error: aborting due to previous error
 

diff --git a/src/test/ui/consts/const-eval/panic-assoc-never-type.rs b/src/test/ui/consts/const-eval/panic-assoc-never-type.rs
@@ -13,4 +13,5 @@ impl PrintName {
 
 fn main() {
     let _ = PrintName::VOID;
+    //~^ ERROR erroneous constant used [E0080]
 }
diff --git a/src/test/ui/consts/const-eval/panic-assoc-never-type.stderr b/src/test/ui/consts/const-eval/panic-assoc-never-type.stderr
@@ -6,6 +6,12 @@ LL |     const VOID: ! = panic!();
    |
    = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to previous error
+error[E0080]: erroneous constant used
+  --> $DIR/panic-assoc-never-type.rs:15:13
+   |
+LL |     let _ = PrintName::VOID;
+   |             ^^^^^^^^^^^^^^^ referenced constant has errors
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
diff --git a/src/test/ui/consts/const-eval/promoted_errors.noopt.stderr b/src/test/ui/consts/const-eval/promoted_errors.noopt.stderr
@@ -1,3 +1,45 @@
+warning: this arithmetic operation will overflow
+  --> $DIR/promoted_errors.rs:15:5
+   |
+LL |     0 - 1
+   |     ^^^^^ attempt to compute `0_u32 - 1_u32`, which would overflow
+   |
+note: the lint level is defined here
+  --> $DIR/promoted_errors.rs:11:20
+   |
+LL | #![warn(const_err, arithmetic_overflow, unconditional_panic)]
+   |                    ^^^^^^^^^^^^^^^^^^^
+
+warning: this operation will panic at runtime
+  --> $DIR/promoted_errors.rs:21:5
+   |
+LL |     1 / 0
+   |     ^^^^^ attempt to divide `1_i32` by zero
+   |
+note: the lint level is defined here
+  --> $DIR/promoted_errors.rs:11:41
+   |
+LL | #![warn(const_err, arithmetic_overflow, unconditional_panic)]
+   |                                         ^^^^^^^^^^^^^^^^^^^
+
+warning: this operation will panic at runtime
+  --> $DIR/promoted_errors.rs:27:5
+   |
+LL |     1 / (1 - 1)
+   |     ^^^^^^^^^^^ attempt to divide `1_i32` by zero
+
+warning: this operation will panic at runtime
+  --> $DIR/promoted_errors.rs:31:5
+   |
+LL |     1 / (false as i32)
+   |     ^^^^^^^^^^^^^^^^^^ attempt to divide `1_i32` by zero
+
+warning: this operation will panic at runtime
+  --> $DIR/promoted_errors.rs:35:5
+   |
+LL |     [1, 2, 3][4]
+   |     ^^^^^^^^^^^^ index out of bounds: the length is 3 but the index is 4
+
 warning: any use of this value will cause an error
   --> $DIR/promoted_errors.rs:15:5
    |
@@ -6,7 +48,7 @@ LL |       0 - 1
    |       |
    |       attempt to compute `0_u32 - 1_u32`, which would overflow
    |       inside `overflow` at $DIR/promoted_errors.rs:15:5
-   |       inside `X` at $DIR/promoted_errors.rs:38:29
+   |       inside `X` at $DIR/promoted_errors.rs:43:29
 ...
 LL | / const X: () = {
 LL | |     let _x: &'static u32 = &overflow();
@@ -26,7 +68,7 @@ LL | #![warn(const_err, arithmetic_overflow, unconditional_panic)]
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
 
 warning: any use of this value will cause an error
-  --> $DIR/promoted_errors.rs:38:28
+  --> $DIR/promoted_errors.rs:43:28
    |
 LL | / const X: () = {
 LL | |     let _x: &'static u32 = &overflow();
@@ -41,5 +83,5 @@ LL | | };
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
 
-warning: 2 warnings emitted
+warning: 7 warnings emitted
 
diff --git a/src/test/ui/consts/const-eval/promoted_errors.opt.stderr b/src/test/ui/consts/const-eval/promoted_errors.opt.stderr
@@ -1,12 +1,54 @@
+warning: this arithmetic operation will overflow
+  --> $DIR/promoted_errors.rs:15:5
+   |
+LL |     0 - 1
+   |     ^^^^^ attempt to compute `0_u32 - 1_u32`, which would overflow
+   |
+note: the lint level is defined here
+  --> $DIR/promoted_errors.rs:11:20
+   |
+LL | #![warn(const_err, arithmetic_overflow, unconditional_panic)]
+   |                    ^^^^^^^^^^^^^^^^^^^
+
+warning: this operation will panic at runtime
+  --> $DIR/promoted_errors.rs:21:5
+   |
+LL |     1 / 0
+   |     ^^^^^ attempt to divide `1_i32` by zero
+   |
+note: the lint level is defined here
+  --> $DIR/promoted_errors.rs:11:41
+   |
+LL | #![warn(const_err, arithmetic_overflow, unconditional_panic)]
+   |                                         ^^^^^^^^^^^^^^^^^^^
+
+warning: this operation will panic at runtime
+  --> $DIR/promoted_errors.rs:27:5
+   |
+LL |     1 / (1 - 1)
+   |     ^^^^^^^^^^^ attempt to divide `1_i32` by zero
+
+warning: this operation will panic at runtime
+  --> $DIR/promoted_errors.rs:31:5
+   |
+LL |     1 / (false as i32)
+   |     ^^^^^^^^^^^^^^^^^^ attempt to divide `1_i32` by zero
+
+warning: this operation will panic at runtime
+  --> $DIR/promoted_errors.rs:35:5
+   |
+LL |     [1, 2, 3][4]
+   |     ^^^^^^^^^^^^ index out of bounds: the length is 3 but the index is 4
+
 warning: any use of this value will cause an error
-  --> $DIR/promoted_errors.rs:20:5
+  --> $DIR/promoted_errors.rs:21:5
    |
 LL |       1 / 0
    |       ^^^^^
    |       |
    |       attempt to divide `1_i32` by zero
-   |       inside `div_by_zero1` at $DIR/promoted_errors.rs:20:5
-   |       inside `X` at $DIR/promoted_errors.rs:41:29
+   |       inside `div_by_zero1` at $DIR/promoted_errors.rs:21:5
+   |       inside `X` at $DIR/promoted_errors.rs:46:29
 ...
 LL | / const X: () = {
 LL | |     let _x: &'static u32 = &overflow();
@@ -26,7 +68,7 @@ LL | #![warn(const_err, arithmetic_overflow, unconditional_panic)]
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
 
 warning: any use of this value will cause an error
-  --> $DIR/promoted_errors.rs:41:28
+  --> $DIR/promoted_errors.rs:46:28
    |
 LL | / const X: () = {
 LL | |     let _x: &'static u32 = &overflow();
@@ -42,5 +84,5 @@ LL | | };
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
 
-warning: 2 warnings emitted
+warning: 7 warnings emitted