4 files changed, 44 insertions, 3 deletions
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index eccde04aff5..ab644e2c65b 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -5873,6 +5873,10 @@ public:
                                  Expr *CastExpr, CastKind &CastKind,
                                  ExprValueKind &VK, CXXCastPath &Path);
 
+  /// \brief Force an expression with unknown-type to an expression of the
+  /// given type.
+  ExprResult forceUnknownAnyToType(Expr *E, QualType ToType);
+                             
   // CheckVectorCast - check type constraints for vectors.
   // Since vectors are an extension, there are no C standard reference for this.
   // We allow casting between vectors and integer datatypes of the same size.
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 12a13f1aa45..1e9f319d4f7 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -3691,6 +3691,11 @@ Sema::ActOnCallExpr(Scope *S, Expr *Fn, SourceLocation LParenLoc,
   }
 
   // If we're directly calling a function, get the appropriate declaration.
+  if (Fn->getType() == Context.UnknownAnyTy) {
+    ExprResult result = rebuildUnknownAnyFunction(*this, Fn);
+    if (result.isInvalid()) return ExprError();
+    Fn = result.take();
+  }
 
   Expr *NakedFn = Fn->IgnoreParens();
 
@@ -10110,6 +10115,10 @@ ExprResult Sema::checkUnknownAnyCast(SourceRange TypeRange, QualType CastType,
   return CastExpr;
 }
 
+ExprResult Sema::forceUnknownAnyToType(Expr *E, QualType ToType) {
+  return RebuildUnknownAnyExpr(*this, ToType).Visit(E);
+}
+
 static ExprResult diagnoseUnknownAnyExpr(Sema &S, Expr *E) {
   Expr *orig = E;
   unsigned diagID = diag::err_uncasted_use_of_unknown_any;
diff --git a/clang/lib/Sema/SemaExprObjC.cpp b/clang/lib/Sema/SemaExprObjC.cpp
index c4f01c093a7..cc17e6b890d 100644
--- a/clang/lib/Sema/SemaExprObjC.cpp
+++ b/clang/lib/Sema/SemaExprObjC.cpp
@@ -1211,9 +1211,13 @@ ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
   // and determine receiver type.
   if (Receiver) {
     if (Receiver->hasPlaceholderType()) {
-      ExprResult result = CheckPlaceholderExpr(Receiver);
-      if (result.isInvalid()) return ExprError();
-      Receiver = result.take();
+      ExprResult Result;
+      if (Receiver->getType() == Context.UnknownAnyTy)
+        Result = forceUnknownAnyToType(Receiver, Context.getObjCIdType());
+      else
+        Result = CheckPlaceholderExpr(Receiver);
+      if (Result.isInvalid()) return ExprError();
+      Receiver = Result.take();
     }
 
     if (Receiver->isTypeDependent()) {
diff --git a/clang/test/SemaObjC/unknown-anytype.m b/clang/test/SemaObjC/unknown-anytype.m
new file mode 100644
index 00000000000..48eb91ae237
--- /dev/null
+++ b/clang/test/SemaObjC/unknown-anytype.m
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -funknown-anytype -fsyntax-only -fdebugger-support -verify %s
+
+extern __unknown_anytype test0;
+extern __unknown_anytype test1();
+
+@interface A
+- (int*)getIntPtr;
+- (double*)getSomePtr;
+@end
+
+@interface B
+- (float*)getFloatPtr;
+- (short*)getSomePtr;
+@end
+
+void test_unknown_anytype_receiver() {
+  int *ip = [test0 getIntPtr];
+  float *fp = [test1() getFloatPtr];
+  double *dp = [test1() getSomePtr]; // okay: picks first method found
+  [[test0 unknownMethod] otherUnknownMethod]; // expected-error{{no known method '-otherUnknownMethod'; cast the message send to the method's return type}}
+  (void)(int)[[test0 unknownMethod] otherUnknownMethod];;
+  [[test1() unknownMethod] otherUnknownMethod]; // expected-error{{no known method '-otherUnknownMethod'; cast the message send to the method's return type}}
+  (void)(id)[[test1() unknownMethod] otherUnknownMethod];
+}