[CSFix] Diagnosing ambiguious involving FunctionArgument mismatches and overloaded ref expression argument

Author: LucianoPAlmeida

include/swift/AST/DiagnosticsSema.def

@@ -245,6 +245,10 @@ ERROR(no_candidates_match_result_type,none,
       "no '%0' candidates produce the expected contextual result type %1",
       (StringRef, Type))
 
+ERROR(no_candidates_match_argument_type,none,
+      "no '%0' candidates produce the expected parameter type %1",
+      (StringRef, Type))
+
 ERROR(cannot_infer_closure_type,none,
       "unable to infer closure type in the current context", ())
 ERROR(cannot_infer_closure_result_type,none,

lib/Sema/CSFix.cpp

@@ -366,6 +366,32 @@ bool AllowFunctionTypeMismatch::coalesceAndDiagnose(
   return failure.diagnose(asNote);
 }
 
+bool AllowFunctionTypeMismatch::diagnoseForAmbiguity(CommonFixesArray commonFixes) const {
+  const Solution *solution;
+  const ConstraintFix *fix;
+  std::tie(solution, fix) = commonFixes.front();
+  auto applyInfo = solution->getFunctionArgApplyInfo(fix->getLocator());
+  if (!applyInfo)
+    return false;
+  
+  if (auto *ODRE = dyn_cast<OverloadedDeclRefExpr>(applyInfo->getArgExpr())) {
+    auto &DE = getConstraintSystem().getASTContext().Diags;
+    
+    DE.diagnose(ODRE->getLoc(), diag::no_candidates_match_argument_type,
+                ODRE->getDecls()[0]->getName().getBaseName().userFacingName(),
+                applyInfo->getParamType());
+    
+    for (auto decl : ODRE->getDecls()) {
+      if (decl->getLoc().isValid())
+        DE.diagnose(decl->getLoc(), diag::found_candidate_type,
+                    decl->getInterfaceType());
+    }
+    return true;
+  }
+  
+  return false;
+}
+
 bool AllowFunctionTypeMismatch::diagnose(const Solution &solution,
                                          bool asNote) const {
   return coalesceAndDiagnose(solution, {}, asNote);

lib/Sema/CSFix.h

@@ -1062,7 +1062,9 @@ class AllowFunctionTypeMismatch final : public ContextualMismatch {
   bool coalesceAndDiagnose(const Solution &solution,
                            ArrayRef<ConstraintFix *> secondaryFixes,
                            bool asNote = false) const override;
-
+  
+  bool diagnoseForAmbiguity(CommonFixesArray commonFixes) const override;
+  
   bool diagnose(const Solution &solution, bool asNote = false) const override;
 };
 

test/Sema/diag_ambiguous_overloads.swift

@@ -151,3 +151,10 @@ func SR12689_2(_ u: Int) {}
 
 SR12689_2(SR12689_1(1 as Double)) // expected-error {{no exact matches in call to global function 'SR12689_1'}}
 SR12689_1(1 as Double) as Int // expected-error {{no exact matches in call to global function 'SR12689_1'}}
+
+// Ambiguos OverloadRefExpr
+func SR12689_O(_ p: Int) {} // expected-note {{found candidate with type '(Int) -> ()'}}
+func SR12689_O(_ p: Double) {} // expected-note {{found candidate with type '(Double) -> ()'}}
+
+func SR12689_3(_ param: (String)-> Void) {}
+SR12689_3(SR12689_O) // expected-error {{no 'SR12689_O' candidates produce the expected parameter type '(String) -> Void'}}