[Sema][ObjC] Fix spurious -Wcast-qual warnings.

We do not meaningfully track object const-ness of Objective-C object
types. Silence the -Wcast-qual warning that is issued when casting to or
from Objective-C object types results in losing const qualification.

rdar://problem/33807915

llvm-svn: 310672

1 files changed, 8 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaCast.cpp b/clang/lib/Sema/SemaCast.cpp
index ba2049d8a60..d603101c3fd 100644
--- a/clang/lib/Sema/SemaCast.cpp
+++ b/clang/lib/Sema/SemaCast.cpp
@@ -552,7 +552,14 @@ CastsAwayConstness(Sema &Self, QualType SrcType, QualType DestType,
     Qualifiers SrcQuals, DestQuals;
     Self.Context.getUnqualifiedArrayType(UnwrappedSrcType, SrcQuals);
     Self.Context.getUnqualifiedArrayType(UnwrappedDestType, DestQuals);
-    
+
+    // We do not meaningfully track object const-ness of Objective-C object
+    // types. Remove const from the source type if either the source or
+    // the destination is an Objective-C object type.
+    if (UnwrappedSrcType->isObjCObjectType() ||
+        UnwrappedDestType->isObjCObjectType())
+      SrcQuals.removeConst();
+
     Qualifiers RetainedSrcQuals, RetainedDestQuals;
     if (CheckCVR) {
       RetainedSrcQuals.setCVRQualifiers(SrcQuals.getCVRQualifiers());