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.
llvm-svn: 158239
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 68f7469..40cc351 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -6303,6 +6303,17 @@
if (getLangOpts().ObjCAutoRefCount && inferObjCARCLifetime(VDecl))
VDecl->setInvalidDecl();
+ // Warn if we deduced 'id'. 'auto' usually implies type-safety, but using
+ // 'id' instead of a specific object type prevents most of our usual checks.
+ // We only want to warn outside of template instantiations, though:
+ // inside a template, the 'id' could have come from a parameter.
+ if (ActiveTemplateInstantiations.empty() &&
+ DeducedType->getType()->isObjCIdType()) {
+ SourceLocation Loc = DeducedType->getTypeLoc().getBeginLoc();
+ Diag(Loc, diag::warn_auto_var_is_id)
+ << VDecl->getDeclName() << DeduceInit->getSourceRange();
+ }
+
// If this is a redeclaration, check that the type we just deduced matches
// the previously declared type.
if (VarDecl *Old = VDecl->getPreviousDecl())