From 9969f6c3052c0683f17a78ab6f223b1db84b6fe8 Mon Sep 17 00:00:00 2001
From: Jordan Rose <jordan_rose@apple.com>
Date: Thu, 10 Nov 2016 23:28:34 +0000
Subject: [PATCH] Don't require nullability on 'va_list'.

There are many non-portable typedefs, but va_list is one that nobody
ever thinks of as a pointer or an array. (When's the last time you saw
someone check for a NULL va_list?) Make an exception for this one
special type.

Part of rdar://problem/25846421.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@286522 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaType.cpp                         | 16 +++++++++++++-
 .../Inputs/nullability-consistency-arrays.h   | 22 +++++++++++++++++++
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/lib/Sema/SemaType.cpp b/lib/Sema/SemaType.cpp
index 0ae53a13d0..13843da081 100644
--- a/lib/Sema/SemaType.cpp
+++ b/lib/Sema/SemaType.cpp
@@ -3919,8 +3919,22 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
         attr->setUsedAsTypeAttr();
       }
     }
+
+    auto isVaList = [&S](QualType T) -> bool {
+      auto *typedefTy = T->getAs<TypedefType>();
+      if (!typedefTy)
+        return false;
+      TypedefDecl *vaListTypedef = S.Context.getBuiltinVaListDecl();
+      do {
+        if (typedefTy->getDecl() == vaListTypedef)
+          return true;
+        typedefTy = typedefTy->desugar()->getAs<TypedefType>();
+      } while (typedefTy);
+      return false;
+    };
+
     if (complainAboutMissingNullability == CAMN_Yes &&
-        T->isArrayType() && !T->getNullability(S.Context) &&
+        T->isArrayType() && !T->getNullability(S.Context) && !isVaList(T) &&
         D.isPrototypeContext() &&
         !hasOuterPointerLikeChunk(D, D.getNumTypeObjects())) {
       checkNullabilityConsistency(S, SimplePointerKind::Array,
diff --git a/test/SemaObjCXX/Inputs/nullability-consistency-arrays.h b/test/SemaObjCXX/Inputs/nullability-consistency-arrays.h
index dda35a6230..900930c7a7 100644
--- a/test/SemaObjCXX/Inputs/nullability-consistency-arrays.h
+++ b/test/SemaObjCXX/Inputs/nullability-consistency-arrays.h
@@ -1,3 +1,5 @@
+#include <stdarg.h>
+
 void firstThingInTheFileThatNeedsNullabilityIsAnArray(int ints[]);
 #if ARRAYS_CHECKED
 // expected-warning@-2 {{array parameter is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified)}}
@@ -33,6 +35,26 @@ void testAllOK(
     void * _Nullable ptrs[_Nonnull],
     void * _Nullable * _Nullable nestedPtrs[_Nonnull]);
 
+void testVAList(va_list ok); // no warning
+
+#if __cplusplus
+// Carefully construct a test case such that if a platform's va_list is an array
+// or pointer type, it gets tested, but otherwise it does not.
+template<class T, class F>
+struct pointer_like_or { typedef F type; };
+template<class T, class F>
+struct pointer_like_or<T*, F> { typedef T *type; };
+template<class T, class F>
+struct pointer_like_or<T* const, F> { typedef T * const type; };
+template<class T, class F>
+struct pointer_like_or<T[], F> { typedef T type[]; };
+template<class T, class F, unsigned size>
+struct pointer_like_or<T[size], F> { typedef T type[size]; };
+
+void testVAListWithNullability(
+  pointer_like_or<va_list, void*>::type _Nonnull x); // no errors
+#endif
+
 void nestedArrays(int x[5][1]) {}
 #if ARRAYS_CHECKED
 // expected-warning@-2 {{array parameter is missing a nullability type specifier (_Nonnull, _Nullable, or _Null_unspecified)}}
-- 
2.40.0