Objective-ARC++: infer template type arguments of
ownership-unqualified retainable object type as __strong. This allows
us to write, e.g.,
std::vector<id>
and we'll infer that the vector's element types have __strong
ownership semantics, which is far nicer than requiring:
std::vector<__strong id>
Note that we allow one to override the ownership qualifier of a
substituted template type parameter, e.g., given
template<typename T>
struct X {
typedef __weak T type;
};
X<id> is treated the same as X<__strong id>. At instantiation type,
the __weak in "__weak T" overrides the (inferred or specified)
__strong on the template argument type, so that we can still provide
metaprogramming transformations.
This is part of <rdar://problem/9595486>.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@133303 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaTemplateDeduction.cpp b/lib/Sema/SemaTemplateDeduction.cpp
index af35931..b5e9c25 100644
--- a/lib/Sema/SemaTemplateDeduction.cpp
+++ b/lib/Sema/SemaTemplateDeduction.cpp
@@ -1016,6 +1016,15 @@
DeducedQs.removeAddressSpace();
if (ParamQs.hasObjCLifetime())
DeducedQs.removeObjCLifetime();
+
+ // Objective-C ARC:
+ // If template deduction would produce an argument type with lifetime type
+ // but no lifetime qualifier, the __strong lifetime qualifier is inferred.
+ if (S.getLangOptions().ObjCAutoRefCount &&
+ DeducedType->isObjCLifetimeType() &&
+ !DeducedQs.hasObjCLifetime())
+ DeducedQs.setObjCLifetime(Qualifiers::OCL_Strong);
+
DeducedType = S.Context.getQualifiedType(DeducedType.getUnqualifiedType(),
DeducedQs);