Rollup merge of rust-lang#147398 - Jamesbarford:fix/method-call-type-inference-error, r=chenyukang

Zalathar · web-flow · commit 79ad10e7acca · 2025-10-07T22:44:19.000+11:00
Fix; correct placement of type inference error for method calls

Addresses a FIXME for displaying errors on method calls;

Before;
```
error[E0282]: type annotations needed
  --&gt; /&lt;location&gt;/src/main.rs:48:15
   |
## |             e.is_conversion_error();
   |               ^^^^^^^^^^^^^^^^^^^ cannot infer type
```

After;

```
error[E0282]: type annotations needed
  --&gt; /&lt;location&gt;/src/main.rs:48:15
   |
## |             e.is_conversion_error();
   |             ^ cannot infer type
```
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -7,9 +7,8 @@ use rustc_attr_parsing::is_doc_alias_attrs_contain_symbol;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::sso::SsoHashSet;
 use rustc_errors::Applicability;
-use rustc_hir as hir;
-use rustc_hir::HirId;
 use rustc_hir::def::DefKind;
+use rustc_hir::{self as hir, ExprKind, HirId, Node};
 use rustc_hir_analysis::autoderef::{self, Autoderef};
 use rustc_infer::infer::canonical::{Canonical, OriginalQueryValues, QueryResponse};
 use rustc_infer::infer::{BoundRegionConversionTime, DefineOpaqueTypes, InferOk, TyCtxtInferExt};
@@ -486,13 +485,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 let ty = self.resolve_vars_if_possible(ty.value);
                 let guar = match *ty.kind() {
                     ty::Infer(ty::TyVar(_)) => {
+                        // We want to get the variable name that the method
+                        // is being called on. If it is a method call.
+                        let err_span = match (mode, self.tcx.hir_node(scope_expr_id)) {
+                            (
+                                Mode::MethodCall,
+                                Node::Expr(hir::Expr {
+                                    kind: ExprKind::MethodCall(_, recv, ..),
+                                    ..
+                                }),
+                            ) => recv.span,
+                            _ => span,
+                        };
+
                         let raw_ptr_call = bad_ty.reached_raw_pointer
                             && !self.tcx.features().arbitrary_self_types();
-                        // FIXME: Ideally we'd use the span of the self-expr here,
-                        // not of the method path.
+
                         let mut err = self.err_ctxt().emit_inference_failure_err(
                             self.body_id,
-                            span,
+                            err_span,
                             ty.into(),
                             TypeAnnotationNeeded::E0282,
                             !raw_ptr_call,
diff --git a/tests/ui/autoref-autoderef/deref-ambiguity-becomes-nonambiguous.stderr b/tests/ui/autoref-autoderef/deref-ambiguity-becomes-nonambiguous.stderr
@@ -5,7 +5,7 @@ LL |     let var_fn = Value::wrap();
    |         ^^^^^^
 ...
 LL |     let _ = var_fn.clone();
-   |                    ----- type must be known at this point
+   |             ------ type must be known at this point
    |
 help: consider giving `var_fn` an explicit type, where the placeholders `_` are specified
    |
diff --git a/tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.next.stderr b/tests/ui/closures/deduce-signature/obligation-with-leaking-placeholders.next.stderr
@@ -5,7 +5,7 @@ LL |     needs_foo(|x| {
    |                ^
 ...
 LL |         x.to_string();
-   |           --------- type must be known at this point
+   |         - type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
diff --git a/tests/ui/impl-trait/hidden-type-is-opaque-2.default.stderr b/tests/ui/impl-trait/hidden-type-is-opaque-2.default.stderr
@@ -5,7 +5,7 @@ LL |     Thunk::new(|mut cont| {
    |                 ^^^^^^^^
 LL |
 LL |         cont.reify_as();
-   |              -------- type must be known at this point
+   |         ---- type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
@@ -19,7 +19,7 @@ LL |     Thunk::new(|mut cont| {
    |                 ^^^^^^^^
 LL |
 LL |         cont.reify_as();
-   |              -------- type must be known at this point
+   |         ---- type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
diff --git a/tests/ui/impl-trait/hidden-type-is-opaque-2.next.stderr b/tests/ui/impl-trait/hidden-type-is-opaque-2.next.stderr
@@ -5,7 +5,7 @@ LL |     Thunk::new(|mut cont| {
    |                 ^^^^^^^^
 LL |
 LL |         cont.reify_as();
-   |              -------- type must be known at this point
+   |         ---- type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
@@ -19,7 +19,7 @@ LL |     Thunk::new(|mut cont| {
    |                 ^^^^^^^^
 LL |
 LL |         cont.reify_as();
-   |              -------- type must be known at this point
+   |         ---- type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
diff --git a/tests/ui/inference/need_type_info/incompat-call-after-qualified-path-0.stderr b/tests/ui/inference/need_type_info/incompat-call-after-qualified-path-0.stderr
@@ -2,7 +2,7 @@ error[E0282]: type annotations needed
   --> $DIR/incompat-call-after-qualified-path-0.rs:21:6
    |
 LL |   f(|a, b| a.cmp(b));
-   |      ^       --- type must be known at this point
+   |      ^     - type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
diff --git a/tests/ui/inference/need_type_info/incompat-call-after-qualified-path-1.stderr b/tests/ui/inference/need_type_info/incompat-call-after-qualified-path-1.stderr
@@ -2,7 +2,7 @@ error[E0282]: type annotations needed
   --> $DIR/incompat-call-after-qualified-path-1.rs:25:6
    |
 LL |   f(|a, b| a.cmp(b));
-   |      ^       --- type must be known at this point
+   |      ^     - type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
diff --git a/tests/ui/issues/issue-20261.stderr b/tests/ui/issues/issue-20261.stderr
@@ -1,8 +1,8 @@
 error[E0282]: type annotations needed
-  --> $DIR/issue-20261.rs:4:11
+  --> $DIR/issue-20261.rs:4:9
    |
 LL |         i.clone();
-   |           ^^^^^ cannot infer type
+   |         ^ cannot infer type
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/issues/issue-2151.stderr b/tests/ui/issues/issue-2151.stderr
@@ -4,7 +4,7 @@ error[E0282]: type annotations needed
 LL |     let x = panic!();
    |         ^
 LL |     x.clone();
-   |       ----- type must be known at this point
+   |     - type must be known at this point
    |
 help: consider giving `x` an explicit type
    |
diff --git a/tests/ui/lazy-type-alias-impl-trait/branches3.stderr b/tests/ui/lazy-type-alias-impl-trait/branches3.stderr
@@ -2,7 +2,7 @@ error[E0282]: type annotations needed
   --> $DIR/branches3.rs:9:10
    |
 LL |         |s| s.len()
-   |          ^    --- type must be known at this point
+   |          ^  - type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
@@ -13,7 +13,7 @@ error[E0282]: type annotations needed
   --> $DIR/branches3.rs:18:10
    |
 LL |         |s| s.len()
-   |          ^    --- type must be known at this point
+   |          ^  - type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
@@ -24,7 +24,7 @@ error[E0282]: type annotations needed
   --> $DIR/branches3.rs:26:10
    |
 LL |         |s| s.len()
-   |          ^    --- type must be known at this point
+   |          ^  - type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
@@ -35,7 +35,7 @@ error[E0282]: type annotations needed
   --> $DIR/branches3.rs:33:10
    |
 LL |         |s| s.len()
-   |          ^    --- type must be known at this point
+   |          ^  - type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
diff --git a/tests/ui/methods/call_method_unknown_pointee.stderr b/tests/ui/methods/call_method_unknown_pointee.stderr
@@ -1,11 +1,10 @@
 error[E0282]: type annotations needed
-  --> $DIR/call_method_unknown_pointee.rs:10:41
+  --> $DIR/call_method_unknown_pointee.rs:10:23
    |
 LL |         let _a: i32 = (ptr as *const _).read();
-   |                                         ^^^^
-   |                                         |
-   |                                         cannot infer type
-   |                                         cannot call a method on a raw pointer with an unknown pointee type
+   |                       ^^^^^^^^^^^^^^^^^ ---- cannot call a method on a raw pointer with an unknown pointee type
+   |                       |
+   |                       cannot infer type
 
 error[E0282]: type annotations needed for `*const _`
   --> $DIR/call_method_unknown_pointee.rs:12:13
@@ -22,13 +21,12 @@ LL |         let b: *const _ = ptr as *const _;
    |              ++++++++++
 
 error[E0282]: type annotations needed
-  --> $DIR/call_method_unknown_pointee.rs:21:39
+  --> $DIR/call_method_unknown_pointee.rs:21:23
    |
 LL |         let _a: i32 = (ptr as *mut _).read();
-   |                                       ^^^^
-   |                                       |
-   |                                       cannot infer type
-   |                                       cannot call a method on a raw pointer with an unknown pointee type
+   |                       ^^^^^^^^^^^^^^^ ---- cannot call a method on a raw pointer with an unknown pointee type
+   |                       |
+   |                       cannot infer type
 
 error[E0282]: type annotations needed for `*mut _`
   --> $DIR/call_method_unknown_pointee.rs:23:13
diff --git a/tests/ui/methods/call_method_unknown_referent.stderr b/tests/ui/methods/call_method_unknown_referent.stderr
@@ -1,14 +1,14 @@
 error[E0282]: type annotations needed
-  --> $DIR/call_method_unknown_referent.rs:20:31
+  --> $DIR/call_method_unknown_referent.rs:20:19
    |
 LL |     let _a: i32 = (ptr as &_).read();
-   |                               ^^^^ cannot infer type
+   |                   ^^^^^^^^^^^ cannot infer type
 
 error[E0282]: type annotations needed
-  --> $DIR/call_method_unknown_referent.rs:26:37
+  --> $DIR/call_method_unknown_referent.rs:26:14
    |
 LL |     let _b = (rc as std::rc::Rc<_>).read();
-   |                                     ^^^^ cannot infer type
+   |              ^^^^^^^^^^^^^^^^^^^^^^ cannot infer type
 
 error[E0599]: no method named `read` found for struct `SmartPtr<T>` in the current scope
   --> $DIR/call_method_unknown_referent.rs:46:35
diff --git a/tests/ui/proc-macro/quote/not-repeatable.stderr b/tests/ui/proc-macro/quote/not-repeatable.stderr
@@ -21,10 +21,10 @@ note: the traits `Iterator` and `ToTokens` must be implemented
   --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
 
 error[E0282]: type annotations needed
-  --> $DIR/not-repeatable.rs:11:13
+  --> $DIR/not-repeatable.rs:11:25
    |
 LL |     let _ = quote! { $($ip)* };
-   |             ^^^^^^^^^^^^^^^^^^ cannot infer type
+   |                         ^^ cannot infer type
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/repeat-expr/copy-inference-side-effects-are-lazy.stderr b/tests/ui/repeat-expr/copy-inference-side-effects-are-lazy.stderr
@@ -5,7 +5,7 @@ LL |     let x = [Foo(PhantomData); 2];
    |         ^
 LL |
 LL |     extract(x).max(2);
-   |                --- type must be known at this point
+   |     ---------- type must be known at this point
    |
 help: consider giving `x` an explicit type, where the placeholders `_` are specified
    |
diff --git a/tests/ui/span/issue-42234-unknown-receiver-type.stderr b/tests/ui/span/issue-42234-unknown-receiver-type.stderr
@@ -4,7 +4,7 @@ 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
+   |     ---------- type must be known at this point
    |
 help: consider specifying the generic argument
    |
@@ -16,8 +16,6 @@ error[E0282]: type annotations needed
    |
 LL |         .sum::<_>()
    |          ^^^ cannot infer type of the type parameter `S` declared on the method `sum`
-LL |         .to_string()
-   |          --------- type must be known at this point
    |
 
 error: aborting due to 2 previous errors
diff --git a/tests/ui/type-alias-impl-trait/closures_in_branches.stderr b/tests/ui/type-alias-impl-trait/closures_in_branches.stderr
@@ -2,7 +2,7 @@ error[E0282]: type annotations needed
   --> $DIR/closures_in_branches.rs:8:10
    |
 LL |         |x| x.len()
-   |          ^    --- type must be known at this point
+   |          ^  - type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
@@ -13,7 +13,7 @@ error[E0282]: type annotations needed
   --> $DIR/closures_in_branches.rs:22:10
    |
 LL |         |x| x.len()
-   |          ^    --- type must be known at this point
+   |          ^  - type must be known at this point
    |
 help: consider giving this closure parameter an explicit type
    |
diff --git a/tests/ui/type-inference/regression-issue-81317.stderr b/tests/ui/type-inference/regression-issue-81317.stderr
@@ -5,7 +5,7 @@ LL |     let iv = S ^ index.into();
    |         ^^
 LL |
 LL |     &iv.to_bytes_be();
-   |         ----------- type must be known at this point
+   |      -- type must be known at this point
    |
 help: consider giving `iv` an explicit type
    |
diff --git a/tests/ui/typeck/issue-13853.stderr b/tests/ui/typeck/issue-13853.stderr
@@ -18,10 +18,10 @@ LL |     for node in graph.iter() {
    |                       ^^^^ method not found in `&G`
 
 error[E0282]: type annotations needed
-  --> $DIR/issue-13853.rs:28:14
+  --> $DIR/issue-13853.rs:28:9
    |
 LL |         node.zomg();
-   |              ^^^^ cannot infer type
+   |         ^^^^ cannot infer type
 
 error[E0308]: mismatched types
   --> $DIR/issue-13853.rs:37:13

Original file line number	Diff line number	Diff line change
`@@ -5,7 +5,7 @@ LL \| let var_fn = Value::wrap();`
`5`	`5`	`\| ^^^^^^`
`6`	`6`	`...`
`7`	`7`	`LL \| let _ = var_fn.clone();`
`8`		`- \| ----- type must be known at this point`
	`8`	`+ \| ------ type must be known at this point`
`9`	`9`	`\|`
`10`	`10`	help: consider giving `var_fn` an explicit type, where the placeholders `_` are specified
`11`	`11`	`\|`
Original file line number	Diff line number	Diff line change
`@@ -5,7 +5,7 @@ LL \| needs_foo(\|x\| {`
`5`	`5`	`\| ^`
`6`	`6`	`...`
`7`	`7`	`LL \| x.to_string();`
`8`		`- \| --------- type must be known at this point`
	`8`	`+ \| - type must be known at this point`
`9`	`9`	`\|`
`10`	`10`	`help: consider giving this closure parameter an explicit type`
`11`	`11`	`\|`
Original file line number	Diff line number	Diff line change
`@@ -5,7 +5,7 @@ LL \| Thunk::new(\|mut cont\| {`
`5`	`5`	`\| ^^^^^^^^`
`6`	`6`	`LL \|`
`7`	`7`	`LL \| cont.reify_as();`
`8`		`- \| -------- type must be known at this point`
	`8`	`+ \| ---- type must be known at this point`
`9`	`9`	`\|`
`10`	`10`	`help: consider giving this closure parameter an explicit type`
`11`	`11`	`\|`
`@@ -19,7 +19,7 @@ LL \| Thunk::new(\|mut cont\| {`
`19`	`19`	`\| ^^^^^^^^`
`20`	`20`	`LL \|`
`21`	`21`	`LL \| cont.reify_as();`
`22`		`- \| -------- type must be known at this point`
	`22`	`+ \| ---- type must be known at this point`
`23`	`23`	`\|`
`24`	`24`	`help: consider giving this closure parameter an explicit type`
`25`	`25`	`\|`
Original file line number	Diff line number	Diff line change
`@@ -2,7 +2,7 @@ error[E0282]: type annotations needed`
`2`	`2`	`--> $DIR/incompat-call-after-qualified-path-0.rs:21:6`
`3`	`3`	`\|`
`4`	`4`	`LL \| f(\|a, b\| a.cmp(b));`
`5`		`- \| ^ --- type must be known at this point`
	`5`	`+ \| ^ - type must be known at this point`
`6`	`6`	`\|`
`7`	`7`	`help: consider giving this closure parameter an explicit type`
`8`	`8`	`\|`
Original file line number	Diff line number	Diff line change
`@@ -1,8 +1,8 @@`
`1`	`1`	`error[E0282]: type annotations needed`
`2`		`- --> $DIR/issue-20261.rs:4:11`
	`2`	`+ --> $DIR/issue-20261.rs:4:9`
`3`	`3`	`\|`
`4`	`4`	`LL \| i.clone();`
`5`		`- \| ^^^^^ cannot infer type`
	`5`	`+ \| ^ cannot infer type`
`6`	`6`
`7`	`7`	`error: aborting due to 1 previous error`
`8`	`8`
Original file line number	Diff line number	Diff line change
`@@ -4,7 +4,7 @@ error[E0282]: type annotations needed`
`4`	`4`	`LL \| let x = panic!();`
`5`	`5`	`\| ^`
`6`	`6`	`LL \| x.clone();`
`7`		`- \| ----- type must be known at this point`
	`7`	`+ \| - type must be known at this point`
`8`	`8`	`\|`
`9`	`9`	help: consider giving `x` an explicit type
`10`	`10`	`\|`
Original file line number	Diff line number	Diff line change
`@@ -2,7 +2,7 @@ error[E0282]: type annotations needed`
`2`	`2`	`--> $DIR/branches3.rs:9:10`
`3`	`3`	`\|`
`4`	`4`	`LL \| \|s\| s.len()`
`5`		`- \| ^ --- type must be known at this point`
	`5`	`+ \| ^ - type must be known at this point`
`6`	`6`	`\|`
`7`	`7`	`help: consider giving this closure parameter an explicit type`
`8`	`8`	`\|`
`@@ -13,7 +13,7 @@ error[E0282]: type annotations needed`
`13`	`13`	`--> $DIR/branches3.rs:18:10`
`14`	`14`	`\|`
`15`	`15`	`LL \| \|s\| s.len()`
`16`		`- \| ^ --- type must be known at this point`
	`16`	`+ \| ^ - type must be known at this point`
`17`	`17`	`\|`
`18`	`18`	`help: consider giving this closure parameter an explicit type`
`19`	`19`	`\|`
`@@ -24,7 +24,7 @@ error[E0282]: type annotations needed`
`24`	`24`	`--> $DIR/branches3.rs:26:10`
`25`	`25`	`\|`
`26`	`26`	`LL \| \|s\| s.len()`
`27`		`- \| ^ --- type must be known at this point`
	`27`	`+ \| ^ - type must be known at this point`
`28`	`28`	`\|`
`29`	`29`	`help: consider giving this closure parameter an explicit type`
`30`	`30`	`\|`
`@@ -35,7 +35,7 @@ error[E0282]: type annotations needed`
`35`	`35`	`--> $DIR/branches3.rs:33:10`
`36`	`36`	`\|`
`37`	`37`	`LL \| \|s\| s.len()`
`38`		`- \| ^ --- type must be known at this point`
	`38`	`+ \| ^ - type must be known at this point`
`39`	`39`	`\|`
`40`	`40`	`help: consider giving this closure parameter an explicit type`
`41`	`41`	`\|`