Merge pull request #10798 from xedin/rdar-33135487-4.0

[4.0] [QoI] Don't try to lookup members on incorrect type while diagnosing keypath components

Author: ematejska

lib/Sema/CSDiag.cpp

@@ -7537,6 +7537,8 @@ static bool diagnoseKeyPathComponents(ConstraintSystem *CS, KeyPathExpr *KPE,
   auto performLookup = [&](Identifier componentName, SourceLoc componentNameLoc,
                            Type &lookupType) -> LookupResult {
     assert(currentType && "Non-beginning state must have a type");
+    if (!currentType->mayHaveMembers())
+      return LookupResult();
 
     // Determine the type in which the lookup should occur. If we have
     // a bridged value type, this will be the Objective-C class to

validation-test/compiler_crashers_2_fixed/0112-rdar33135487.swift

@@ -0,0 +1,8 @@
+// RUN: not %target-swift-frontend %s -typecheck
+
+enum State<StateType> {
+  func put<StateType>() -> StateType {}
+  func put<T>(keyPath: WritableKeyPath<StateType, T>, projection: T) {
+    put(keyPath: \.age, projection: {})
+  }
+}