[PATCH] D31177: [ARC][ObjC++] Use ObjC semantic rules for comparisons between a pointer and objective-c object pointer

[Alex Lorenz via Phabricator via cfe-commits]

arphaman created this revision.

When ARC is enabled in Objective-C++, comparisons between a pointer and Objective-C object pointer typically result in errors like this: `invalid operands to a binary expression`. This error message can be quite confusing as it doesn't provide a solution to the problem, unlike the non-C++ diagnostic: `implicit conversion of Objective-C pointer type 'id' to C pointer type 'void *' requires a bridged cast` (it also provides fix-its). This patch forces comparisons between pointers and objective-c object pointers in ARC to use the Objective-C semantic rules to ensure that a better diagnostic is reported.


Repository:
  rL LLVM

https://reviews.llvm.org/D31177

Files:
  lib/Sema/SemaExpr.cpp
  test/SemaObjCXX/arc-ptr-comparison.mm


Index: test/SemaObjCXX/arc-ptr-comparison.mm
===================================================================
--- /dev/null
+++ test/SemaObjCXX/arc-ptr-comparison.mm
@@ -0,0 +1,24 @@
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-apple-darwin11 -fsyntax-only -fobjc-arc -verify %s
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-apple-darwin11 -fsyntax-only -verify -DNOARC %s
+#ifdef NOARC
+// expected-no-diagnostics
+#endif
+
+int testObjCComparisonRules(void *v, id x, id y) {
+  return v == x;
+#ifndef NOARC
+// expected-error at -2 {{implicit conversion of Objective-C pointer type 'id' to C pointer type 'void *' requires a bridged cast}}
+// expected-note at -3 {{use __bridge to convert directly (no change in ownership)}}
+// expected-note at -4 {{use __bridge_retained to make an ARC object available as a +1 'void *'}}
+#endif
+  return v >= x;
+#ifndef NOARC
+// expected-error at -2 {{implicit conversion of Objective-C pointer type 'id' to C pointer type 'void *' requires a bridged cast}}
+// expected-note at -3 {{use __bridge to convert directly (no change in ownership)}}
+// expected-note at -4 {{use __bridge_retained to make an ARC object available as a +1 'void *'}}
+#endif
+  return v == (id)(void *)0; // OK
+  return v == nullptr; // OK
+  return v == (void *)0;
+  return x == y;
+}
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -9424,7 +9424,11 @@
     //   If both operands are pointers, [...] bring them to their composite
     //   pointer type.
     if ((int)LHSType->isPointerType() + (int)RHSType->isPointerType() >=
-        (IsRelational ? 2 : 1)) {
+        (IsRelational || (LangOpts.ObjCAutoRefCount &&
+                          (LHSType->isObjCObjectPointerType() ||
+                           RHSType->isObjCObjectPointerType()))
+             ? 2
+             : 1)) {
       if (convertPointersToCompositeType(*this, Loc, LHS, RHS))
         return QualType();
       else


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D31177.92445.patch
Type: text/x-patch
Size: 2008 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20170321/67ac360b/attachment.bin>