Point at bounds when comparing impl items to trait

15 files changed, 62 insertions, 54 deletions

diff --git a/compiler/rustc_typeck/src/check/compare_method.rs b/compiler/rustc_typeck/src/check/compare_method.rs
index 89495570375..bcb53b2e437 100644
--- a/compiler/rustc_typeck/src/check/compare_method.rs
+++ b/compiler/rustc_typeck/src/check/compare_method.rs
@@ -210,12 +210,8 @@ fn compare_predicate_entailment<'tcx>(
     let normalize_cause = traits::ObligationCause::misc(impl_m_span, impl_m_hir_id);
     let param_env =
         ty::ParamEnv::new(tcx.intern_predicates(&hybrid_preds.predicates), Reveal::UserFacing);
-    let param_env = traits::normalize_param_env_or_error(
-        tcx,
-        impl_m.def_id,
-        param_env,
-        normalize_cause.clone(),
-    );
+    let param_env =
+        traits::normalize_param_env_or_error(tcx, impl_m.def_id, param_env, normalize_cause);
 
     tcx.infer_ctxt().enter(|infcx| {
         let inh = Inherited::new(infcx, impl_m.def_id.expect_local());
@@ -226,12 +222,22 @@ fn compare_predicate_entailment<'tcx>(
         let mut selcx = traits::SelectionContext::new(&infcx);
 
         let impl_m_own_bounds = impl_m_predicates.instantiate_own(tcx, impl_to_placeholder_substs);
-        for predicate in impl_m_own_bounds.predicates {
+        for (predicate, span) in iter::zip(impl_m_own_bounds.predicates, impl_m_own_bounds.spans) {
+            let normalize_cause = traits::ObligationCause::misc(span, impl_m_hir_id);
             let traits::Normalized { value: predicate, obligations } =
-                traits::normalize(&mut selcx, param_env, normalize_cause.clone(), predicate);
+                traits::normalize(&mut selcx, param_env, normalize_cause, predicate);
 
             inh.register_predicates(obligations);
-            inh.register_predicate(traits::Obligation::new(cause.clone(), param_env, predicate));
+            let cause = ObligationCause::new(
+                span,
+                impl_m_hir_id,
+                ObligationCauseCode::CompareImplMethodObligation {
+                    item_name: impl_m.ident.name,
+                    impl_item_def_id: impl_m.def_id,
+                    trait_item_def_id: trait_m.def_id,
+                },
+            );
+            inh.register_predicate(traits::Obligation::new(cause, param_env, predicate));
         }
 
         // We now need to check that the signature of the impl method is
@@ -280,6 +286,12 @@ fn compare_predicate_entailment<'tcx>(
 
         let sub_result = infcx.at(&cause, param_env).sup(trait_fty, impl_fty).map(
             |InferOk { obligations, .. }| {
+                // FIXME: We'd want to keep more accurate spans than "the method signature" when
+                // processing the comparison between the trait and impl fn, but we sadly lose them
+                // and point at the whole signature when a trait bound or specific input or output
+                // type would be more appropriate. In other places we have a `Vec<Span>`
+                // corresponding to their `Vec<Predicate>`, but we don't have that here.
+                // Fixing this would improve the output of test `issue-83765.rs`.
                 inh.register_predicates(obligations);
             },
         );
diff --git a/src/test/ui/borrowck/regions-bound-missing-bound-in-impl.stderr b/src/test/ui/borrowck/regions-bound-missing-bound-in-impl.stderr
index 536fd43ef75..1e3b071ef92 100644
--- a/src/test/ui/borrowck/regions-bound-missing-bound-in-impl.stderr
+++ b/src/test/ui/borrowck/regions-bound-missing-bound-in-impl.stderr
@@ -64,13 +64,13 @@ LL |     fn wrong_bound2(self, b: Inv, c: Inv, d: Inv) {
    |                    ^ lifetimes do not match method in trait
 
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/regions-bound-missing-bound-in-impl.rs:49:5
+  --> $DIR/regions-bound-missing-bound-in-impl.rs:49:26
    |
 LL |     fn another_bound<'x: 'a>(self, x: Inv<'x>, y: Inv<'t>);
    |     ------------------------------------------------------- definition of `another_bound` from trait
 ...
 LL |     fn another_bound<'x: 't>(self, x: Inv<'x>, y: Inv<'t>) {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `'x: 't`
+   |                          ^^ impl has extra requirement `'x: 't`
 
 error: aborting due to 6 previous errors
 
diff --git a/src/test/ui/compare-method/proj-outlives-region.stderr b/src/test/ui/compare-method/proj-outlives-region.stderr
index e5f5c5ed20d..797a8167931 100644
--- a/src/test/ui/compare-method/proj-outlives-region.stderr
+++ b/src/test/ui/compare-method/proj-outlives-region.stderr
@@ -1,11 +1,11 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/proj-outlives-region.rs:9:5
+  --> $DIR/proj-outlives-region.rs:9:23
    |
 LL |     fn foo() where T: 'a;
    |     --------------------- definition of `foo` from trait
 ...
 LL |     fn foo() where U: 'a { }
-   |     ^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `U: 'a`
+   |                       ^^ impl has extra requirement `U: 'a`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/compare-method/region-extra-2.stderr b/src/test/ui/compare-method/region-extra-2.stderr
index 420d99c15ec..f01d7f4710c 100644
--- a/src/test/ui/compare-method/region-extra-2.stderr
+++ b/src/test/ui/compare-method/region-extra-2.stderr
@@ -1,11 +1,11 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/region-extra-2.rs:9:5
+  --> $DIR/region-extra-2.rs:9:53
    |
 LL |     fn renew<'b: 'a>(self) -> &'b mut [T];
    |     -------------------------------------- definition of `renew` from trait
 ...
 LL |     fn renew<'b: 'a>(self) -> &'b mut [T] where 'a: 'b {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `'a: 'b`
+   |                                                     ^^ impl has extra requirement `'a: 'b`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/compare-method/region-extra.stderr b/src/test/ui/compare-method/region-extra.stderr
index 5a584c7d6ed..4a3af65e904 100644
--- a/src/test/ui/compare-method/region-extra.stderr
+++ b/src/test/ui/compare-method/region-extra.stderr
@@ -1,11 +1,11 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/region-extra.rs:9:5
+  --> $DIR/region-extra.rs:9:24
    |
 LL |     fn foo();
    |     --------- definition of `foo` from trait
 ...
 LL |     fn foo() where 'a: 'b { }
-   |     ^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `'a: 'b`
+   |                        ^^ impl has extra requirement `'a: 'b`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/compare-method/region-unrelated.stderr b/src/test/ui/compare-method/region-unrelated.stderr
index fd3576ddcf1..f7ae6f94438 100644
--- a/src/test/ui/compare-method/region-unrelated.stderr
+++ b/src/test/ui/compare-method/region-unrelated.stderr
@@ -1,11 +1,11 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/region-unrelated.rs:9:5
+  --> $DIR/region-unrelated.rs:9:23
    |
 LL |     fn foo() where T: 'a;
    |     --------------------- definition of `foo` from trait
 ...
 LL |     fn foo() where V: 'a { }
-   |     ^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `V: 'a`
+   |                       ^^ impl has extra requirement `V: 'a`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/compare-method/trait-bound-on-type-parameter.stderr b/src/test/ui/compare-method/trait-bound-on-type-parameter.stderr
index 83a2ae60681..ce6885c1541 100644
--- a/src/test/ui/compare-method/trait-bound-on-type-parameter.stderr
+++ b/src/test/ui/compare-method/trait-bound-on-type-parameter.stderr
@@ -1,11 +1,11 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/trait-bound-on-type-parameter.rs:15:5
+  --> $DIR/trait-bound-on-type-parameter.rs:15:13
    |
 LL |   fn b<C,D>(&self, x: C) -> C;
    |   ---------------------------- definition of `b` from trait
 ...
 LL |     fn b<F: Sync, G>(&self, _x: F) -> F { panic!() }
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `F: Sync`
+   |             ^^^^ impl has extra requirement `F: Sync`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/compare-method/traits-misc-mismatch-1.stderr b/src/test/ui/compare-method/traits-misc-mismatch-1.stderr
index da94fc65841..805c04536ca 100644
--- a/src/test/ui/compare-method/traits-misc-mismatch-1.stderr
+++ b/src/test/ui/compare-method/traits-misc-mismatch-1.stderr
@@ -1,65 +1,65 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/traits-misc-mismatch-1.rs:27:5
+  --> $DIR/traits-misc-mismatch-1.rs:27:26
    |
 LL |     fn test_error1_fn<T: Eq>(&self);
    |     -------------------------------- definition of `test_error1_fn` from trait
 ...
 LL |     fn test_error1_fn<T: Ord>(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `T: Ord`
+   |                          ^^^ impl has extra requirement `T: Ord`
 
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/traits-misc-mismatch-1.rs:31:5
+  --> $DIR/traits-misc-mismatch-1.rs:31:31
    |
 LL |     fn test_error2_fn<T: Eq + Ord>(&self);
    |     -------------------------------------- definition of `test_error2_fn` from trait
 ...
 LL |     fn test_error2_fn<T: Eq + B>(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `T: B`
+   |                               ^ impl has extra requirement `T: B`
 
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/traits-misc-mismatch-1.rs:35:5
+  --> $DIR/traits-misc-mismatch-1.rs:35:26
    |
 LL |     fn test_error3_fn<T: Eq + Ord>(&self);
    |     -------------------------------------- definition of `test_error3_fn` from trait
 ...
 LL |     fn test_error3_fn<T: B + Eq>(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `T: B`
+   |                          ^ impl has extra requirement `T: B`
 
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/traits-misc-mismatch-1.rs:45:5
+  --> $DIR/traits-misc-mismatch-1.rs:45:26
    |
 LL |     fn test_error5_fn<T: A>(&self);
    |     ------------------------------- definition of `test_error5_fn` from trait
 ...
 LL |     fn test_error5_fn<T: B>(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `T: B`
+   |                          ^ impl has extra requirement `T: B`
 
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/traits-misc-mismatch-1.rs:51:5
+  --> $DIR/traits-misc-mismatch-1.rs:51:30
    |
 LL |     fn test_error7_fn<T: A>(&self);
    |     ------------------------------- definition of `test_error7_fn` from trait
 ...
 LL |     fn test_error7_fn<T: A + Eq>(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `T: Eq`
+   |                              ^^ impl has extra requirement `T: Eq`
 
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/traits-misc-mismatch-1.rs:54:5
+  --> $DIR/traits-misc-mismatch-1.rs:54:26
    |
 LL |     fn test_error8_fn<T: B>(&self);
    |     ------------------------------- definition of `test_error8_fn` from trait
 ...
 LL |     fn test_error8_fn<T: C>(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `T: C`
+   |                          ^ impl has extra requirement `T: C`
 
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/traits-misc-mismatch-1.rs:67:5
+  --> $DIR/traits-misc-mismatch-1.rs:67:18
    |
 LL |     fn method<G:Getter<isize>>(&self);
    |     ---------------------------------- definition of `method` from trait
 ...
 LL |     fn method<G: Getter<usize>>(&self) {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `G: Getter<usize>`
+   |                  ^^^^^^^^^^^^^ impl has extra requirement `G: Getter<usize>`
 
 error: aborting due to 7 previous errors
 
diff --git a/src/test/ui/compare-method/traits-misc-mismatch-2.stderr b/src/test/ui/compare-method/traits-misc-mismatch-2.stderr
index acf94ad32b1..36bb764d40e 100644
--- a/src/test/ui/compare-method/traits-misc-mismatch-2.stderr
+++ b/src/test/ui/compare-method/traits-misc-mismatch-2.stderr
@@ -1,11 +1,11 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/traits-misc-mismatch-2.rs:13:5
+  --> $DIR/traits-misc-mismatch-2.rs:13:18
    |
 LL |     fn zip<B, U: Iterator<U>>(self, other: U) -> ZipIterator<Self, U>;
    |     ------------------------------------------------------------------ definition of `zip` from trait
 ...
 LL |     fn zip<B, U: Iterator<B>>(self, other: U) -> ZipIterator<T, U> {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `U: Iterator<B>`
+   |                  ^^^^^^^^^^^ impl has extra requirement `U: Iterator<B>`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/error-codes/E0276.stderr b/src/test/ui/error-codes/E0276.stderr
index 8857e1646ee..1013f041bbe 100644
--- a/src/test/ui/error-codes/E0276.stderr
+++ b/src/test/ui/error-codes/E0276.stderr
@@ -1,11 +1,11 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/E0276.rs:6:5
+  --> $DIR/E0276.rs:6:30
    |
 LL |     fn foo<T>(x: T);
    |     ---------------- definition of `foo` from trait
 ...
 LL |     fn foo<T>(x: T) where T: Copy {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `T: Copy`
+   |                              ^^^^ impl has extra requirement `T: Copy`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/generic-associated-types/impl_bounds.stderr b/src/test/ui/generic-associated-types/impl_bounds.stderr
index f47b5f81e25..1c8a1f09af5 100644
--- a/src/test/ui/generic-associated-types/impl_bounds.stderr
+++ b/src/test/ui/generic-associated-types/impl_bounds.stderr
@@ -59,10 +59,10 @@ LL | impl<T: std::marker::Copy> Foo for Fooy<T> {
    |       +++++++++++++++++++
 
 error[E0277]: the trait bound `T: Copy` is not satisfied
-  --> $DIR/impl_bounds.rs:22:5
+  --> $DIR/impl_bounds.rs:22:24
    |
 LL |     fn d() where Self: Copy {}
-   |     ^^^^^^^^^^^^^^^^^^^^^^^ the trait `Copy` is not implemented for `T`
+   |                        ^^^^ the trait `Copy` is not implemented for `T`
    |
 note: required because of the requirements on the impl of `Copy` for `Fooy<T>`
   --> $DIR/impl_bounds.rs:11:10
diff --git a/src/test/ui/impl-trait/issue-55872-1.stderr b/src/test/ui/impl-trait/issue-55872-1.stderr
index e772445a56c..2d1142fd0c5 100644
--- a/src/test/ui/impl-trait/issue-55872-1.stderr
+++ b/src/test/ui/impl-trait/issue-55872-1.stderr
@@ -1,11 +1,11 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/issue-55872-1.rs:12:5
+  --> $DIR/issue-55872-1.rs:12:15
    |
 LL |     fn foo<T>() -> Self::E;
    |     ----------------------- definition of `foo` from trait
 ...
 LL |     fn foo<T: Default>() -> Self::E {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `T: Default`
+   |               ^^^^^^^ impl has extra requirement `T: Default`
 
 error[E0277]: the trait bound `S: Copy` is not satisfied in `(S, T)`
   --> $DIR/issue-55872-1.rs:12:29
diff --git a/src/test/ui/issues/issue-14853.stderr b/src/test/ui/issues/issue-14853.stderr
index 6fc10550492..2adcf55eca9 100644
--- a/src/test/ui/issues/issue-14853.stderr
+++ b/src/test/ui/issues/issue-14853.stderr
@@ -1,11 +1,11 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/issue-14853.rs:12:5
+  --> $DIR/issue-14853.rs:12:15
    |
 LL |     fn yay<T: Debug>(_: Option<Self>, thing: &[T]);
    |     ----------------------------------------------- definition of `yay` from trait
 ...
 LL |     fn yay<T: Str>(_:Option<X>, thing: &[T]) {
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ impl has extra requirement `T: Str`
+   |               ^^^ impl has extra requirement `T: Str`
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-18937.rs b/src/test/ui/issues/issue-18937.rs
index ab4c9c736d8..af85e5b2b02 100644
--- a/src/test/ui/issues/issue-18937.rs
+++ b/src/test/ui/issues/issue-18937.rs
@@ -16,8 +16,8 @@ trait A<'a> {
 }
 
 impl<'a> A<'a> for B {
-    fn foo<F>(&mut self, f: F) //~ ERROR impl has stricter
-        where F: fmt::Debug + 'static,
+    fn foo<F>(&mut self, f: F)
+        where F: fmt::Debug + 'static, //~ ERROR impl has stricter
     {
         self.list.push(Box::new(f));
     }
diff --git a/src/test/ui/issues/issue-18937.stderr b/src/test/ui/issues/issue-18937.stderr
index ac302caecc3..5e2ba0ef4fc 100644
--- a/src/test/ui/issues/issue-18937.stderr
+++ b/src/test/ui/issues/issue-18937.stderr
@@ -1,17 +1,13 @@
 error[E0276]: impl has stricter requirements than trait
-  --> $DIR/issue-18937.rs:19:5
+  --> $DIR/issue-18937.rs:20:31
    |
 LL | /     fn foo<F>(&mut self, f: F)
 LL | |         where F: fmt::Debug + 'a,
 LL | |               Self: Sized;
    | |__________________________- definition of `foo` from trait
 ...
-LL | /     fn foo<F>(&mut self, f: F)
-LL | |         where F: fmt::Debug + 'static,
-LL | |     {
-LL | |         self.list.push(Box::new(f));
-LL | |     }
-   | |_____^ impl has extra requirement `F: 'static`
+LL |           where F: fmt::Debug + 'static,
+   |                                 ^^^^^^^ impl has extra requirement `F: 'static`
 
 error: aborting due to previous error