Don't require nullability on template parameters in typedefs.

Previously the following code would warn on the use of "T":

  template <typename T>
  struct X {
    typedef T *type;
  };

...because nullability is /allowed/ on template parameters (because
they could be pointers). (Actually putting nullability on this use of
'T' will of course break if the argument is a non-pointer type.)

This fix doesn't handle the case where a template parameter is used
/outside/ of a typedef. That seems trickier, especially in parameter
position.

llvm-svn: 285856

clang/lib/Sema/SemaType.cpp

@@ -3600,7 +3600,17 @@ static TypeSourceInfo *GetFullTypeForDeclarator(TypeProcessingState &state,
     // inner pointers.
     complainAboutMissingNullability = CAMN_InnerPointers;
 
-    if (T->canHaveNullability() && !T->getNullability(S.Context)) {
+    auto isDependentNonPointerType = [](QualType T) -> bool {
+      // Note: This is intended to be the same check as Type::canHaveNullability
+      // except with all of the ambiguous cases being treated as 'false' rather
+      // than 'true'.
+      return T->isDependentType() && !T->isAnyPointerType() &&
+        !T->isBlockPointerType() && !T->isMemberPointerType();
+    };
+
+    if (T->canHaveNullability() && !T->getNullability(S.Context) &&
+        !isDependentNonPointerType(T)) {
+      // Note that we allow but don't require nullability on dependent types.
       ++NumPointersRemaining;
     }
 

clang/test/SemaObjCXX/Inputs/nullability-consistency-1.h

@@ -13,5 +13,13 @@ class X {
   int X:: *memptr; // expected-warning{{member pointer is missing a nullability type specifier}}
 };
 
+template <typename T>
+struct Typedefs {
+  typedef T *Base; // no-warning
+  typedef Base *type; // expected-warning{{pointer is missing a nullability type specifier}}
+};
+
+Typedefs<int> xx;
+Typedefs<void *> yy;