On E0283, point at method with the requirements

On required type annotation diagnostic error, point at method with the
requirements if the span is available.

Author: estebank

src/librustc/traits/error_reporting.rs

@@ -1241,7 +1241,13 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             }
             ObligationCauseCode::ItemObligation(item_def_id) => {
                 let item_name = tcx.item_path_str(item_def_id);
-                err.note(&format!("required by `{}`", item_name));
+                let msg = format!("required by `{}`", item_name);
+                if let Some(sp) = tcx.hir.span_if_local(item_def_id) {
+                    let sp = tcx.sess.codemap().def_span(sp);
+                    err.span_note(sp, &msg);
+                } else {
+                    err.note(&msg);
+                }
             }
             ObligationCauseCode::ObjectCastObligation(object_ty) => {
                 err.note(&format!("required for the cast to the object type `{}`",

src/test/ui/anonymous-higher-ranked-lifetime.stderr

@@ -6,7 +6,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'r, 's> fn(&'r (), &'s ()) -> _`
    |
-   = note: required by `f1`
+note: required by `f1`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:26:1
+   |
+26 | fn f1<F>(_: F) where F: Fn(&(), &()) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/anonymous-higher-ranked-lifetime.rs:13:5
@@ -16,7 +20,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'a, 'r> fn(&'a (), &'r ()) -> _`
    |
-   = note: required by `f2`
+note: required by `f2`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:27:1
+   |
+27 | fn f2<F>(_: F) where F: for<'a> Fn(&'a (), &()) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/anonymous-higher-ranked-lifetime.rs:14:5
@@ -26,7 +34,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'r> fn(&(), &'r ()) -> _`
    |
-   = note: required by `f3`
+note: required by `f3`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:28:1
+   |
+28 | fn f3<'a, F>(_: F) where F: Fn(&'a (), &()) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/anonymous-higher-ranked-lifetime.rs:15:5
@@ -36,7 +48,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'s, 'r> fn(&'s (), &'r ()) -> _`
    |
-   = note: required by `f4`
+note: required by `f4`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:29:1
+   |
+29 | fn f4<F>(_: F) where F: for<'r> Fn(&(), &'r ()) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/anonymous-higher-ranked-lifetime.rs:16:5
@@ -46,7 +62,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'r> fn(&'r (), &'r ()) -> _`
    |
-   = note: required by `f5`
+note: required by `f5`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:30:1
+   |
+30 | fn f5<F>(_: F) where F: for<'r> Fn(&'r (), &'r ()) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/anonymous-higher-ranked-lifetime.rs:17:5
@@ -56,7 +76,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'r> fn(&'r (), std::boxed::Box<for<'s> std::ops::Fn(&'s ()) + 'static>) -> _`
    |
-   = note: required by `g1`
+note: required by `g1`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:33:1
+   |
+33 | fn g1<F>(_: F) where F: Fn(&(), Box<Fn(&())>) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/anonymous-higher-ranked-lifetime.rs:18:5
@@ -66,7 +90,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'r> fn(&'r (), for<'s> fn(&'s ())) -> _`
    |
-   = note: required by `g2`
+note: required by `g2`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:34:1
+   |
+34 | fn g2<F>(_: F) where F: Fn(&(), fn(&())) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/anonymous-higher-ranked-lifetime.rs:19:5
@@ -76,7 +104,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'s> fn(&'s (), std::boxed::Box<for<'r> std::ops::Fn(&'r ()) + 'static>) -> _`
    |
-   = note: required by `g3`
+note: required by `g3`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:35:1
+   |
+35 | fn g3<F>(_: F) where F: for<'s> Fn(&'s (), Box<Fn(&())>) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/anonymous-higher-ranked-lifetime.rs:20:5
@@ -86,7 +118,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'s> fn(&'s (), for<'r> fn(&'r ())) -> _`
    |
-   = note: required by `g4`
+note: required by `g4`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:36:1
+   |
+36 | fn g4<F>(_: F) where F: Fn(&(), for<'r> fn(&'r ())) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/anonymous-higher-ranked-lifetime.rs:21:5
@@ -96,7 +132,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'r, 's> fn(&'r (), std::boxed::Box<for<'t0> std::ops::Fn(&'t0 ()) + 'static>, &'s (), for<'t0, 't1> fn(&'t0 (), &'t1 ())) -> _`
    |
-   = note: required by `h1`
+note: required by `h1`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:39:1
+   |
+39 | fn h1<F>(_: F) where F: Fn(&(), Box<Fn(&())>, &(), fn(&(), &())) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/anonymous-higher-ranked-lifetime.rs:22:5
@@ -106,7 +146,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `for<'r, 't0> fn(&'r (), std::boxed::Box<for<'s> std::ops::Fn(&'s ()) + 'static>, &'t0 (), for<'s, 't1> fn(&'s (), &'t1 ())) -> _`
    |
-   = note: required by `h2`
+note: required by `h2`
+  --> $DIR/anonymous-higher-ranked-lifetime.rs:40:1
+   |
+40 | fn h2<F>(_: F) where F: for<'t0> Fn(&(), Box<Fn(&())>, &'t0 (), fn(&(), &())) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 11 previous errors
 

src/test/ui/did_you_mean/issue-39802-show-5-trait-impls.stderr

@@ -10,7 +10,11 @@ error[E0277]: the trait bound `i8: Foo<i32>` is not satisfied
              <i8 as Foo<u32>>
              <i8 as Foo<u64>>
              <i8 as Foo<bool>>
-   = note: required by `Foo::bar`
+note: required by `Foo::bar`
+  --> $DIR/issue-39802-show-5-trait-impls.rs:12:5
+   |
+12 |     fn bar(&self){}
+   |     ^^^^^^^^^^^^^
 
 error[E0277]: the trait bound `u8: Foo<i32>` is not satisfied
   --> $DIR/issue-39802-show-5-trait-impls.rs:35:5
@@ -23,7 +27,11 @@ error[E0277]: the trait bound `u8: Foo<i32>` is not satisfied
              <u8 as Foo<u32>>
              <u8 as Foo<u64>>
              <u8 as Foo<bool>>
-   = note: required by `Foo::bar`
+note: required by `Foo::bar`
+  --> $DIR/issue-39802-show-5-trait-impls.rs:12:5
+   |
+12 |     fn bar(&self){}
+   |     ^^^^^^^^^^^^^
 
 error[E0277]: the trait bound `bool: Foo<i32>` is not satisfied
   --> $DIR/issue-39802-show-5-trait-impls.rs:36:5
@@ -37,7 +45,11 @@ error[E0277]: the trait bound `bool: Foo<i32>` is not satisfied
              <bool as Foo<u32>>
              <bool as Foo<u64>>
            and 2 others
-   = note: required by `Foo::bar`
+note: required by `Foo::bar`
+  --> $DIR/issue-39802-show-5-trait-impls.rs:12:5
+   |
+12 |     fn bar(&self){}
+   |     ^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors
 

src/test/ui/did_you_mean/recursion_limit.stderr

@@ -15,7 +15,11 @@ error[E0275]: overflow evaluating the requirement `K: std::marker::Send`
    = note: required because it appears within the type `C`
    = note: required because it appears within the type `B`
    = note: required because it appears within the type `A`
-   = note: required by `is_send`
+note: required by `is_send`
+  --> $DIR/recursion_limit.rs:41:1
+   |
+41 | fn is_send<T:Send>() { }
+   | ^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 

src/test/ui/fmt/send-sync.stderr

@@ -12,7 +12,11 @@ error[E0277]: the trait bound `*mut std::ops::Fn() + 'static: std::marker::Sync`
    = note: required because it appears within the type `[std::fmt::ArgumentV1<'_>]`
    = note: required because of the requirements on the impl of `std::marker::Send` for `&[std::fmt::ArgumentV1<'_>]`
    = note: required because it appears within the type `std::fmt::Arguments<'_>`
-   = note: required by `send`
+note: required by `send`
+  --> $DIR/send-sync.rs:11:1
+   |
+11 | fn send<T: Send>(_: T) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0277]: the trait bound `*mut std::ops::Fn() + 'static: std::marker::Sync` is not satisfied in `std::fmt::Arguments<'_>`
   --> $DIR/send-sync.rs:19:5
@@ -28,7 +32,11 @@ error[E0277]: the trait bound `*mut std::ops::Fn() + 'static: std::marker::Sync`
    = note: required because it appears within the type `[std::fmt::ArgumentV1<'_>]`
    = note: required because it appears within the type `&[std::fmt::ArgumentV1<'_>]`
    = note: required because it appears within the type `std::fmt::Arguments<'_>`
-   = note: required by `sync`
+note: required by `sync`
+  --> $DIR/send-sync.rs:12:1
+   |
+12 | fn sync<T: Sync>(_: T) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 2 previous errors
 

src/test/ui/generator/not-send-sync.stderr

@@ -7,7 +7,11 @@ error[E0277]: the trait bound `std::cell::Cell<i32>: std::marker::Sync` is not s
    = help: the trait `std::marker::Sync` is not implemented for `std::cell::Cell<i32>`
    = note: required because of the requirements on the impl of `std::marker::Send` for `&std::cell::Cell<i32>`
    = note: required because it appears within the type `[generator@$DIR/not-send-sync.rs:26:17: 30:6 a:&std::cell::Cell<i32> _]`
-   = note: required by `main::assert_send`
+note: required by `main::assert_send`
+  --> $DIR/not-send-sync.rs:17:5
+   |
+17 |     fn assert_send<T: Send>(_: T) {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0277]: the trait bound `std::cell::Cell<i32>: std::marker::Sync` is not satisfied in `[generator@$DIR/not-send-sync.rs:19:17: 23:6 (std::cell::Cell<i32>, ())]`
   --> $DIR/not-send-sync.rs:19:5
@@ -18,7 +22,11 @@ error[E0277]: the trait bound `std::cell::Cell<i32>: std::marker::Sync` is not s
    = help: within `[generator@$DIR/not-send-sync.rs:19:17: 23:6 (std::cell::Cell<i32>, ())]`, the trait `std::marker::Sync` is not implemented for `std::cell::Cell<i32>`
    = note: required because it appears within the type `(std::cell::Cell<i32>, ())`
    = note: required because it appears within the type `[generator@$DIR/not-send-sync.rs:19:17: 23:6 (std::cell::Cell<i32>, ())]`
-   = note: required by `main::assert_sync`
+note: required by `main::assert_sync`
+  --> $DIR/not-send-sync.rs:16:5
+   |
+16 |     fn assert_sync<T: Sync>(_: T) {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 2 previous errors
 

src/test/ui/impl-trait/auto-trait-leak.stderr

@@ -7,7 +7,11 @@ error[E0277]: the trait bound `std::rc::Rc<std::cell::Cell<i32>>: std::marker::S
    = help: within `impl std::ops::Fn<(i32,)>`, the trait `std::marker::Send` is not implemented for `std::rc::Rc<std::cell::Cell<i32>>`
    = note: required because it appears within the type `[closure@$DIR/auto-trait-leak.rs:21:5: 21:22 p:std::rc::Rc<std::cell::Cell<i32>>]`
    = note: required because it appears within the type `impl std::ops::Fn<(i32,)>`
-   = note: required by `send`
+note: required by `send`
+  --> $DIR/auto-trait-leak.rs:24:1
+   |
+24 | fn send<T: Send>(_: T) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0277]: the trait bound `std::rc::Rc<std::cell::Cell<i32>>: std::marker::Send` is not satisfied in `impl std::ops::Fn<(i32,)>`
   --> $DIR/auto-trait-leak.rs:30:5
@@ -18,7 +22,11 @@ error[E0277]: the trait bound `std::rc::Rc<std::cell::Cell<i32>>: std::marker::S
    = help: within `impl std::ops::Fn<(i32,)>`, the trait `std::marker::Send` is not implemented for `std::rc::Rc<std::cell::Cell<i32>>`
    = note: required because it appears within the type `[closure@$DIR/auto-trait-leak.rs:38:5: 38:22 p:std::rc::Rc<std::cell::Cell<i32>>]`
    = note: required because it appears within the type `impl std::ops::Fn<(i32,)>`
-   = note: required by `send`
+note: required by `send`
+  --> $DIR/auto-trait-leak.rs:24:1
+   |
+24 | fn send<T: Send>(_: T) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0391]: unsupported cyclic reference between types/traits detected
   --> $DIR/auto-trait-leak.rs:44:1

src/test/ui/issue-24424.stderr

@@ -4,7 +4,11 @@ error[E0283]: type annotations required: cannot resolve `T0: Trait0<'l0>`
 14 | impl <'l0, 'l1, T0> Trait1<'l0, T0> for bool where T0 : Trait0<'l0>, T0 : Trait0<'l1> {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: required by `Trait0`
+note: required by `Trait0`
+  --> $DIR/issue-24424.rs:12:1
+   |
+12 | trait Trait0<'l0>  {}
+   | ^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 

src/test/ui/mismatched_types/E0631.stderr

@@ -6,7 +6,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `fn(usize) -> _`
    |
-   = note: required by `foo`
+note: required by `foo`
+  --> $DIR/E0631.rs:13:1
+   |
+13 | fn foo<F: Fn(usize)>(_: F) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in closure arguments
   --> $DIR/E0631.rs:18:5
@@ -16,7 +20,11 @@ error[E0631]: type mismatch in closure arguments
    |     |
    |     expected signature of `fn(usize) -> _`
    |
-   = note: required by `bar`
+note: required by `bar`
+  --> $DIR/E0631.rs:14:1
+   |
+14 | fn bar<F: Fn<usize>>(_: F) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in function arguments
   --> $DIR/E0631.rs:19:5
@@ -27,7 +35,11 @@ error[E0631]: type mismatch in function arguments
 19 |     foo(f); //~ ERROR type mismatch
    |     ^^^ expected signature of `fn(usize) -> _`
    |
-   = note: required by `foo`
+note: required by `foo`
+  --> $DIR/E0631.rs:13:1
+   |
+13 | fn foo<F: Fn(usize)>(_: F) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0631]: type mismatch in function arguments
   --> $DIR/E0631.rs:20:5
@@ -38,7 +50,11 @@ error[E0631]: type mismatch in function arguments
 20 |     bar(f); //~ ERROR type mismatch
    |     ^^^ expected signature of `fn(usize) -> _`
    |
-   = note: required by `bar`
+note: required by `bar`
+  --> $DIR/E0631.rs:14:1
+   |
+14 | fn bar<F: Fn<usize>>(_: F) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 4 previous errors
 

src/test/ui/mismatched_types/closure-arg-count.stderr

@@ -30,7 +30,11 @@ error[E0593]: closure is expected to take 1 argument, but it takes 0 arguments
    |     |
    |     expected closure that takes 1 argument
    |
-   = note: required by `f`
+note: required by `f`
+  --> $DIR/closure-arg-count.rs:13:1
+   |
+13 | fn f<F: Fn<usize>>(_: F) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0593]: closure is expected to take a single tuple as argument, but it takes 2 distinct arguments
   --> $DIR/closure-arg-count.rs:24:53

src/test/ui/mismatched_types/closure-arg-type-mismatch.stderr

@@ -31,15 +31,23 @@ error[E0631]: type mismatch in function arguments
    |     expected signature of `for<'r> fn(*mut &'r u32) -> _`
    |     found signature of `fn(*mut &'a u32) -> _`
    |
-   = note: required by `baz`
+note: required by `baz`
+  --> $DIR/closure-arg-type-mismatch.rs:18:1
+   |
+18 | fn baz<F: Fn(*mut &u32)>(_: F) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0271]: type mismatch resolving `for<'r> <fn(*mut &'a u32) as std::ops::FnOnce<(*mut &'r u32,)>>::Output == ()`
   --> $DIR/closure-arg-type-mismatch.rs:20:5
    |
 20 |     baz(f); //~ ERROR type mismatch
    |     ^^^ expected bound lifetime parameter, found concrete lifetime
    |
-   = note: required by `baz`
+note: required by `baz`
+  --> $DIR/closure-arg-type-mismatch.rs:18:1
+   |
+18 | fn baz<F: Fn(*mut &u32)>(_: F) {}
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 5 previous errors