Fix; correct placement of type inference error for method calls

Author: Jamesbarford

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,

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
  |

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
  |

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
  |

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
  |

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
  |

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
  |

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
 

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
  |

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
  |