Only label place where type is needed if span is meaningful

compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs

@@ -313,11 +313,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
     pub fn emit_inference_failure_err(
         &self,
         body_id: Option<hir::BodyId>,
-        span: Span,
+        failure_span: Span,
         arg: GenericArg<'tcx>,
         // FIXME(#94483): Either use this or remove it.
         _impl_candidates: Vec<ty::TraitRef<'tcx>>,
         error_code: TypeAnnotationNeeded,
+        should_label_span: bool,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
         let arg = self.resolve_vars_if_possible(arg);
         let arg_data = self.extract_inference_diagnostics_data(arg, None);
@@ -326,7 +327,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             // If we don't have any typeck results we're outside
             // of a body, so we won't be able to get better info
             // here.
-            return self.bad_inference_failure_err(span, arg_data, error_code);
+            return self.bad_inference_failure_err(failure_span, arg_data, error_code);
         };
         let typeck_results = typeck_results.borrow();
         let typeck_results = &typeck_results;
@@ -338,7 +339,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         }
 
         let Some(InferSource { span, kind }) = local_visitor.infer_source else {
-            return self.bad_inference_failure_err(span, arg_data, error_code)
+            return self.bad_inference_failure_err(failure_span, arg_data, error_code)
         };
 
         let error_code = error_code.into();
@@ -347,6 +348,11 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             &format!("type annotations needed{}", kind.ty_msg(self)),
             error_code,
         );
+
+        if should_label_span && !failure_span.overlaps(span) {
+            err.span_label(failure_span, "type must be known at this point");
+        }
+
         match kind {
             InferSourceKind::LetBinding { insert_span, pattern_name, ty } => {
                 let suggestion_msg = if let Some(name) = pattern_name {

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -2002,6 +2002,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
                             subst,
                             vec![],
                             ErrorCode::E0282,
+                            false,
                         )
                         .emit();
                     }
@@ -2019,6 +2020,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
                     subst,
                     impl_candidates,
                     ErrorCode::E0283,
+                    false,
                 );
 
                 let obligation = Obligation::new(
@@ -2110,7 +2112,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
                     return;
                 }
 
-                self.emit_inference_failure_err(body_id, span, arg, vec![], ErrorCode::E0282)
+                self.emit_inference_failure_err(body_id, span, arg, vec![], ErrorCode::E0282, false)
             }
 
             ty::PredicateKind::Subtype(data) => {
@@ -2124,7 +2126,14 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
                 let SubtypePredicate { a_is_expected: _, a, b } = data;
                 // both must be type variables, or the other would've been instantiated
                 assert!(a.is_ty_var() && b.is_ty_var());
-                self.emit_inference_failure_err(body_id, span, a.into(), vec![], ErrorCode::E0282)
+                self.emit_inference_failure_err(
+                    body_id,
+                    span,
+                    a.into(),
+                    vec![],
+                    ErrorCode::E0282,
+                    false,
+                )
             }
             ty::PredicateKind::Projection(data) => {
                 let self_ty = data.projection_ty.self_ty();
@@ -2140,6 +2149,7 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
                         self_ty.into(),
                         vec![],
                         ErrorCode::E0284,
+                        false,
                     );
                     err.note(&format!("cannot satisfy `{}`", predicate));
                     err

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -1538,9 +1538,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             ty
         } else {
             if !self.is_tainted_by_errors() {
-                self.emit_inference_failure_err((**self).body_id, sp, ty.into(), vec![], E0282)
+                self.emit_inference_failure_err(
-                    .note("type must be known at this point")
+                    (**self).body_id,
-                    .emit();
+                    sp,
+                    ty.into(),
+                    vec![],
+                    E0282,
+                    true,
+                )
+                .emit();
             }
             let err = self.tcx.ty_error();
             self.demand_suptype(sp, err, ty);

compiler/rustc_typeck/src/check/writeback.rs

@@ -694,6 +694,7 @@ impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
                     t.into(),
                     vec![],
                     E0282,
+                    false,
                 )
                 .emit();
         }
@@ -708,6 +709,7 @@ impl<'cx, 'tcx> Resolver<'cx, 'tcx> {
                     c.into(),
                     vec![],
                     E0282,
+                    false,
                 )
                 .emit();
         }

src/test/ui/array-slice-vec/infer_array_len.stderr

@@ -4,7 +4,6 @@ error[E0282]: type annotations needed
 LL |     let [_, _] = a.into();
    |         ^^^^^^
    |
-   = note: type must be known at this point
 help: consider giving this pattern a type
    |
 LL |     let [_, _]: _ = a.into();

src/test/ui/array-slice-vec/slice-pat-type-mismatches.stderr

@@ -27,8 +27,6 @@ error[E0282]: type annotations needed
    |
 LL |         [] => {}
    |         ^^ cannot infer type
-   |
-   = note: type must be known at this point
 
 error: aborting due to 5 previous errors
 

src/test/ui/cast/issue-85586.stderr

@@ -3,8 +3,6 @@ error[E0282]: type annotations needed
    |
 LL |     let b = (a + 1) as usize;
    |             ^^^^^^^ cannot infer type
-   |
-   = note: type must be known at this point
 
 error: aborting due to previous error
 

src/test/ui/impl-trait/hidden-type-is-opaque-2.stderr

@@ -3,16 +3,12 @@ error[E0282]: type annotations needed
    |
 LL |         cont.reify_as();
    |         ^^^^ cannot infer type
-   |
-   = note: type must be known at this point
 
 error[E0282]: type annotations needed
   --> $DIR/hidden-type-is-opaque-2.rs:18:9
    |
 LL |         cont.reify_as();
    |         ^^^^ cannot infer type
-   |
-   = note: type must be known at this point
 
 error: aborting due to 2 previous errors
 

src/test/ui/issues/issue-15965.stderr

@@ -5,8 +5,6 @@ LL | /         { return () }
 LL | |
 LL | |     ()
    | |______^ cannot infer type
-   |
-   = note: type must be known at this point
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-20261.stderr

@@ -3,8 +3,6 @@ error[E0282]: type annotations needed
    |
 LL |         i.clone();
    |           ^^^^^ cannot infer type
-   |
-   = note: type must be known at this point
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-2151.stderr

@@ -3,8 +3,9 @@ error[E0282]: type annotations needed
    |
 LL |     let x = panic!();
    |         ^
+LL |     x.clone();
+   |     - type must be known at this point
    |
-   = note: type must be known at this point
 help: consider giving `x` an explicit type
    |
 LL |     let x: _ = panic!();

src/test/ui/issues/issue-51116.rs

@@ -5,7 +5,6 @@ fn main() {
             *tile = 0;
             //~^ ERROR type annotations needed
             //~| NOTE cannot infer type
-            //~| NOTE type must be known at this point
         }
     }
 

src/test/ui/issues/issue-51116.stderr

@@ -3,8 +3,6 @@ error[E0282]: type annotations needed
    |
 LL |             *tile = 0;
    |             ^^^^^ cannot infer type
-   |
-   = note: type must be known at this point
 
 error: aborting due to previous error
 

src/test/ui/pattern/issue-88074-pat-range-type-inference-err.stderr

@@ -12,8 +12,6 @@ error[E0282]: type annotations needed
    |
 LL |         Zero::ZERO ..= Zero::ZERO => {},
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type
-   |
-   = note: type must be known at this point
 
 error: aborting due to 2 previous errors
 

src/test/ui/pattern/pat-tuple-bad-type.stderr

@@ -3,8 +3,10 @@ error[E0282]: type annotations needed
    |
 LL |     let x;
    |         ^
+...
+LL |         (..) => {}
+   |         ---- type must be known at this point
    |
-   = note: type must be known at this point
 help: consider giving `x` an explicit type
    |
 LL |     let x: _;

src/test/ui/span/issue-42234-unknown-receiver-type.full.stderr

@@ -3,8 +3,9 @@ error[E0282]: type annotations needed
    |
 LL |     let x: Option<_> = None;
    |                        ^^^^ cannot infer type of the type parameter `T` declared on the enum `Option`
+LL |     x.unwrap().method_that_could_exist_on_some_type();
+   |     ---------- type must be known at this point
    |
-   = note: type must be known at this point
 help: consider specifying the generic argument
    |
 LL |     let x: Option<_> = None::<T>;
@@ -16,7 +17,6 @@ error[E0282]: type annotations needed
 LL |         .sum::<_>()
    |          ^^^ cannot infer type of the type parameter `S` declared on the associated function `sum`
    |
-   = note: type must be known at this point
 help: consider specifying the generic argument
    |
 LL |         .sum::<_>()

src/test/ui/span/issue-42234-unknown-receiver-type.generic_arg.stderr

@@ -3,8 +3,9 @@ error[E0282]: type annotations needed
    |
 LL |     let x: Option<_> = None;
    |                        ^^^^ cannot infer type of the type parameter `T` declared on the enum `Option`
+LL |     x.unwrap().method_that_could_exist_on_some_type();
+   |     ---------- type must be known at this point
    |
-   = note: type must be known at this point
 help: consider specifying the generic argument
    |
 LL |     let x: Option<_> = None::<T>;
@@ -16,7 +17,6 @@ error[E0282]: type annotations needed
 LL |         .sum::<_>()
    |          ^^^ cannot infer type of the type parameter `S` declared on the associated function `sum`
    |
-   = note: type must be known at this point
 help: consider specifying the generic argument
    |
 LL |         .sum::<S>()

src/test/ui/span/method-and-field-eager-resolution.stderr

@@ -3,8 +3,10 @@ error[E0282]: type annotations needed
    |
 LL |     let mut x = Default::default();
    |         ^^^^^
+LL |
+LL |     x.0;
+   |     - type must be known at this point
    |
-   = note: type must be known at this point
 help: consider giving `x` an explicit type
    |
 LL |     let mut x: _ = Default::default();
@@ -15,8 +17,10 @@ error[E0282]: type annotations needed
    |
 LL |     let mut x = Default::default();
    |         ^^^^^
+LL |
+LL |     x[0];
+   |     - type must be known at this point
    |
-   = note: type must be known at this point
 help: consider giving `x` an explicit type
    |
 LL |     let mut x: _ = Default::default();

src/test/ui/span/type-annotations-needed-expr.stderr

@@ -4,7 +4,6 @@ error[E0282]: type annotations needed
 LL |     let _ = (vec![1,2,3]).into_iter().sum() as f64;
    |                                       ^^^ cannot infer type of the type parameter `S` declared on the associated function `sum`
    |
-   = note: type must be known at this point
 help: consider specifying the generic argument
    |
 LL |     let _ = (vec![1,2,3]).into_iter().sum::<S>() as f64;

src/test/ui/type-alias-impl-trait/closures_in_branches.stderr

@@ -14,9 +14,8 @@ error[E0282]: type annotations needed
   --> $DIR/closures_in_branches.rs:21:10
    |
 LL |         |x| x.len()
-   |          ^
+   |          ^  - type must be known at this point
    |
-   = note: type must be known at this point
 help: consider giving this closure parameter an explicit type
    |
 LL |         |x: _| x.len()

src/test/ui/typeck/issue-65611.stderr

@@ -3,8 +3,6 @@ error[E0282]: type annotations needed
    |
 LL |     let x = buffer.last().unwrap().0.clone();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for type parameter `T`
-   |
-   = note: type must be known at this point
 
 error[E0609]: no field `0` on type `&_`
   --> $DIR/issue-65611.rs:59:36

src/test/ui/unboxed-closures/unboxed-closures-failed-recursive-fn-2.stderr

@@ -3,8 +3,10 @@ error[E0282]: type annotations needed for `Option<T>`
    |
 LL |     let mut closure0 = None;
    |         ^^^^^^^^^^^^
+...
+LL |                         return c();
+   |                                --- type must be known at this point
    |
-   = note: type must be known at this point
 help: consider giving `closure0` an explicit type, where the placeholders `_` are specified
    |
 LL |     let mut closure0: Option<T> = None;