Beginning changes to provide more info out about unresolved params, but even

changing is<UnresolvedType> to hasUnresolvedType turns out is enough to fix a
radar.

Author: gregomni

lib/Sema/CalleeCandidateInfo.cpp

@@ -376,11 +376,6 @@ CalleeCandidateInfo::evaluateCloseness(UncurriedCandidate candidate,
       auto argType = getParamResultType(actualArgs[argNo]);
       auto rArgType = argType->getRValueType();
 
-      // If the argument has an unresolved type, then we're not actually
-      // matching against it.
-      if (rArgType->is<UnresolvedType>())
-        continue;
-      
       // FIXME: Right now, a "matching" overload is one with a parameter whose
       // type is identical to the argument type, or substitutable via handling
       // of functions with primary archetypes in one or more parameters.
@@ -391,7 +386,7 @@ CalleeCandidateInfo::evaluateCloseness(UncurriedCandidate candidate,
       bool matched;
       if (paramType->hasUnresolvedType())
         matched = true;
-      else if (rArgType->hasTypeVariable())
+      else if (rArgType->hasTypeVariable() || rArgType->hasUnresolvedType())
         matched = false;
       else {
         auto matchType = paramType;
@@ -476,10 +471,14 @@ CalleeCandidateInfo::evaluateCloseness(UncurriedCandidate candidate,
       if (matched)
         continue;
 
-      if (archetypesMap.empty())
-        mismatchesAreNearMisses &= argumentMismatchIsNearMiss(argType, paramType);
-      
-      ++mismatchingArgs;
+      // If the real argument is unresolved, the candidate isn't a mismatch because
+      // the type could be anything, but it's still useful to save the argument as
+      // failureInfo.
+      if (!rArgType->hasUnresolvedType()) {
+        if (archetypesMap.empty())
+          mismatchesAreNearMisses &= argumentMismatchIsNearMiss(argType, paramType);
+        ++mismatchingArgs;
+      }
 
       failureInfo.argumentNumber = argNo;
       failureInfo.parameterType = paramType;
@@ -489,7 +488,7 @@ CalleeCandidateInfo::evaluateCloseness(UncurriedCandidate candidate,
   }
 
   if (mismatchingArgs == 0)
-    return { CC_ExactMatch, {}};
+    return { CC_ExactMatch, failureInfo};
 
   // Check to see if the first argument expects an inout argument, but is not
   // an lvalue.

test/Constraints/diagnostics.swift

@@ -139,7 +139,7 @@ func ***~(_: Int, _: String) { }
 i ***~ i // expected-error{{cannot convert value of type 'Int' to expected argument type 'String'}}
 
 @available(*, unavailable, message: "call the 'map()' method on the sequence")
-public func myMap<C : Collection, T>(
+public func myMap<C : Collection, T>( // expected-note {{'myMap' has been explicitly marked unavailable here}}
   _ source: C, _ transform: (C.Iterator.Element) -> T
 ) -> [T] {
   fatalError("unavailable function can't be called")
@@ -151,10 +151,8 @@ public func myMap<T, U>(_ x: T?, _ f: (T) -> U) -> U? {
 }
 
 // <rdar://problem/20142523>
-// FIXME: poor diagnostic, to be fixed in 20142462. For now, we just want to
-// make sure that it doesn't crash.
 func rdar20142523() {
-  myMap(0..<10, { x in // expected-error{{ambiguous reference to member '..<'}}
+  myMap(0..<10, { x in // expected-error{{'myMap' is unavailable: call the 'map()' method on the sequence}}
     ()
     return x
   })