---

yaml
---
r: 325999
b: refs/heads/master-next
c: 34a12aa
h: refs/heads/master
i:
  325997: 7fe062e
  325995: 4668a81
  325991: bbff5fa
  325983: d7be5ba

Author: xedin

[refs]

@@ -1,6 +1,6 @@
 ---
 refs/heads/master: e052da7d8886fa0439677852e8f7830b20c2e1da
-refs/heads/master-next: 0f24f7e05a9e640264a1a067a4ef57b891754f5a
+refs/heads/master-next: 34a12aa30e5f697cbbffd4a355e71ae8ffb1fa4d
 refs/tags/osx-passed: b6b74147ef8a386f532cf9357a1bde006e552c54
 refs/tags/swift-2.2-SNAPSHOT-2015-12-01-a: 6bb18e013c2284f2b45f5f84f2df2887dc0f7dea
 refs/tags/swift-2.2-SNAPSHOT-2015-12-01-b: 66d897bfcf64a82cb9a87f5e663d889189d06d07

branches/master-next/include/swift/AST/DiagnosticsSema.def

@@ -379,6 +379,11 @@ ERROR(cannot_convert_default_arg_value_nil,none,
 ERROR(cannot_convert_argument_value,none,
       "cannot convert value of type %0 to expected argument type %1",
       (Type,Type))
+
+NOTE(candidate_has_invalid_argument_at_position,none,
+     "candidate expects value of type %0 at psoition #%1",
+     (Type, unsigned))
+
 ERROR(cannot_convert_argument_value_generic,none,
       "cannot convert value of type %0 (%1) to expected argument type %2 (%3)",
       (Type, StringRef, Type, StringRef))

branches/master-next/lib/Sema/CSDiagnostics.cpp

@@ -4447,3 +4447,25 @@ void InOutConversionFailure::fixItChangeArgumentType() const {
                  actualType, neededType)
       .fixItReplaceChars(startLoc, endLoc, scratch);
 }
+
+bool ArgumentMismatchFailure::diagnoseAsError() {
+  emitDiagnostic(getLoc(), diag::cannot_convert_argument_value, getFromType(),
+                 getToType());
+  return true;
+}
+
+bool ArgumentMismatchFailure::diagnoseAsNote() {
+  auto *locator = getLocator();
+  auto argToParam = locator->findFirst<LocatorPathElt::ApplyArgToParam>();
+  assert(argToParam);
+
+  if (auto overload = getChoiceFor(getRawAnchor())) {
+    if (auto *decl = overload->choice.getDeclOrNull()) {
+      emitDiagnostic(decl, diag::candidate_has_invalid_argument_at_position,
+                     getToType(), argToParam->getParamIdx());
+      return true;
+    }
+  }
+
+  return false;
+}

branches/master-next/lib/Sema/CSDiagnostics.h

@@ -1599,6 +1599,26 @@ class InvalidTupleSplatWithSingleParameterFailure final
   bool diagnoseAsError() override;
 };
 
+/// Diagnose a situation there is a mismatch between argument and parameter
+/// types e.g.:
+///
+/// ```swift
+/// func foo(_: String) {}
+/// func bar(_ v: Int) { foo(v) } // `Int` is not convertible to `String`
+/// ```
+class ArgumentMismatchFailure : public ContextualFailure {
+public:
+  ArgumentMismatchFailure(Expr *root, ConstraintSystem &cs, Type argType,
+                          Type paramType, ConstraintLocator *locator)
+      : ContextualFailure(root, cs, argType, paramType, locator) {}
+
+  bool diagnoseAsError() override;
+  bool diagnoseAsNote() override;
+
+protected:
+  SourceLoc getLoc() const { return getAnchor()->getLoc(); }
+};
+
 /// Provides information about the application of a function argument to a
 /// parameter.
 class FunctionArgApplyInfo {

branches/master-next/lib/Sema/CSFix.cpp

@@ -774,7 +774,10 @@ AllowInOutConversion *AllowInOutConversion::create(ConstraintSystem &cs,
 }
 
 bool AllowArgumentMismatch::diagnose(Expr *root, bool asNote) const {
-  return false;
+  auto &cs = getConstraintSystem();
+  ArgumentMismatchFailure failure(root, cs, getFromType(), getToType(),
+                                  getLocator());
+  return failure.diagnose(asNote);
 }
 
 AllowArgumentMismatch *