Warn in ObjC++ when an 'auto' variable deduces type 'id'.

This could happen for cases like this:

- (NSArray *)getAllNames:(NSArray *)images {
  NSMutableArray *results = [NSMutableArray array];
  for (auto img in images) {
    [results addObject:img.name];
  }
  return results;
}

Here the property access will fail because 'img' has type 'id', rather than,
say, NSImage.

This warning will not fire in templated code, since the 'id' could have
come from a template parameter.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158239 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 0 deletions

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index e50138dccf..235c6abdae 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1469,6 +1469,10 @@ def warn_cxx98_compat_unicode_type : Warning<
 // Objective-C++
 def err_objc_decls_may_only_appear_in_global_scope : Error<
   "Objective-C declarations may only appear in global scope">;
+def warn_auto_var_is_id : Warning<
+  "'auto' deduced as 'id' in declaration of %0">,
+  InGroup<DiagGroup<"auto-var-id">>;
+
 // Attributes
 def err_nsobject_attribute : Error<
   "__attribute ((NSObject)) is for pointer types only">;