r285856 - Don't require nullability on template parameters in typedefs.

[Richard Smith via cfe-commits]

On 2 Nov 2016 1:53 pm, "Jordan Rose via cfe-commits" <
cfe-commits at lists.llvm.org> wrote:

Author: jrose
Date: Wed Nov  2 15:44:07 2016
New Revision: 285856

URL: http://llvm.org/viewvc/llvm-project?rev=285856&view=rev
Log:
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 doesn't make any sense to me. Why would T need to be a pointer type
for a nullability qualifier to be valid on a T*?

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

Modified:
    cfe/trunk/lib/Sema/SemaType.cpp
    cfe/trunk/test/SemaObjCXX/Inputs/nullability-consistency-1.h

Modified: cfe/trunk/lib/Sema/SemaType.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/
SemaType.cpp?rev=285856&r1=285855&r2=285856&view=diff
============================================================
==================
--- cfe/trunk/lib/Sema/SemaType.cpp (original)
+++ cfe/trunk/lib/Sema/SemaType.cpp Wed Nov  2 15:44:07 2016
@@ -3600,7 +3600,17 @@ static TypeSourceInfo *GetFullTypeForDec
     // 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;
     }


Modified: cfe/trunk/test/SemaObjCXX/Inputs/nullability-consistency-1.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/
SemaObjCXX/Inputs/nullability-consistency-1.h?rev=285856&r1=
285855&r2=285856&view=diff
============================================================
==================
--- cfe/trunk/test/SemaObjCXX/Inputs/nullability-consistency-1.h (original)
+++ cfe/trunk/test/SemaObjCXX/Inputs/nullability-consistency-1.h Wed Nov  2
15:44:07 2016
@@ -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;




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