[Diagnostics] Attach note about erased result type to the call instead of declaration

Since the inference is a call site specific it makes sense to attach
a candidate note to the call itself instead of the declaration used.

Author: xedin

lib/Sema/CSDiagnostics.cpp

@@ -8152,21 +8152,10 @@ bool MissingExplicitExistentialCoercion::diagnoseAsError() {
 }
 
 bool MissingExplicitExistentialCoercion::diagnoseAsNote() {
-  auto selectedOverload = getCalleeOverloadChoiceIfAvailable(getLocator());
-  if (!selectedOverload)
-    return false;
-
-  const auto &choice = selectedOverload->choice;
-
-  if (auto *decl = choice.getDeclOrNull()) {
-    auto diagnostic = emitDiagnosticAt(
-        decl, diag::candidate_result_requires_explicit_coercion,
-        ErasedResultType);
-    fixIt(diagnostic);
-    return true;
-  }
-
-  return false;
+  auto diagnostic = emitDiagnostic(
+      diag::candidate_result_requires_explicit_coercion, ErasedResultType);
+  fixIt(diagnostic);
+  return true;
 }
 
 void MissingExplicitExistentialCoercion::fixIt(

test/Constraints/opened_existentials.swift

@@ -233,7 +233,6 @@ func testExplicitCoercionRequirement(v: any B, otherV: any B & D) {
   func getComplex<T: B>(_: T) -> ([(x: (a: T.C, b: Int), y: Int)], [Int: T.C]) { fatalError() }
 
   func overloaded<T: B>(_: T) -> (x: Int, y: T.C) { fatalError() }
-  // expected-note@-1 {{inferred result type '(x: Int, y: any P)' requires explicit coercion due to loss of generic requirements}} {{251:20-20=as (x: Int, y: any P)}}
   func overloaded<T: P>(_: T) -> Int { 42 }
   // expected-note@-1 {{candidate requires that 'any B' conform to 'P' (requirement specified as 'T' : 'P')}}
 
@@ -249,6 +248,7 @@ func testExplicitCoercionRequirement(v: any B, otherV: any B & D) {
   _ = getComplex(v) as ([(x: (a: any P, b: Int), y: Int)], [Int : any P]) // Ok
 
   _ = overloaded(v) // expected-error {{no exact matches in call to local function 'overloaded'}}
+  // expected-note@-1 {{inferred result type '(x: Int, y: any P)' requires explicit coercion due to loss of generic requirements}} {{20-20=as (x: Int, y: any P)}}
 
   func acceptsAny<T>(_: T) {}