[PATCH] D39301: Ignore implicity casts for zero-as-null-pointer-constant warning

[Erich Keane via Phabricator via cfe-commits]

erichkeane created this revision.

The repro in https://bugs.llvm.org/show_bug.cgi?id=34362
caused the left nullptr to be cast to a int* implicitly, which
resulted diagnosing this falsely.


https://reviews.llvm.org/D39301

Files:
  lib/Sema/Sema.cpp
  test/SemaCXX/warn-zero-nullptr.cpp


Index: lib/Sema/Sema.cpp
===================================================================
--- lib/Sema/Sema.cpp
+++ lib/Sema/Sema.cpp
@@ -438,7 +438,7 @@
 void Sema::diagnoseZeroToNullptrConversion(CastKind Kind, const Expr* E) {
   if (Kind != CK_NullToPointer && Kind != CK_NullToMemberPointer)
     return;
-  if (E->getType()->isNullPtrType())
+  if (E->IgnoreImpCasts()->getType()->isNullPtrType())
     return;
   // nullptr only exists from C++11 on, so don't warn on its absence earlier.
   if (!getLangOpts().CPlusPlus11)
Index: test/SemaCXX/warn-zero-nullptr.cpp
===================================================================
--- test/SemaCXX/warn-zero-nullptr.cpp
+++ test/SemaCXX/warn-zero-nullptr.cpp
@@ -25,3 +25,7 @@
 // Warn on these too. Matches gcc and arguably makes sense.
 void* pp = (decltype(nullptr))0; // expected-warning{{zero as null pointer 
constant}}
 void* pp2 = static_cast<decltype(nullptr)>(0); // expected-warning{{zero as 
null pointer constant}}
+
+// Shouldn't warn.
+struct pr34362 { operator int*() { return nullptr; } };
+void pr34362_func() { if (nullptr == pr34362()) {} }



Index: lib/Sema/Sema.cpp
===================================================================
--- lib/Sema/Sema.cpp
+++ lib/Sema/Sema.cpp
@@ -438,7 +438,7 @@
 void Sema::diagnoseZeroToNullptrConversion(CastKind Kind, const Expr* E) {
   if (Kind != CK_NullToPointer && Kind != CK_NullToMemberPointer)
     return;
-  if (E->getType()->isNullPtrType())
+  if (E->IgnoreImpCasts()->getType()->isNullPtrType())
     return;
   // nullptr only exists from C++11 on, so don't warn on its absence earlier.
   if (!getLangOpts().CPlusPlus11)
Index: test/SemaCXX/warn-zero-nullptr.cpp
===================================================================
--- test/SemaCXX/warn-zero-nullptr.cpp
+++ test/SemaCXX/warn-zero-nullptr.cpp
@@ -25,3 +25,7 @@
 // Warn on these too. Matches gcc and arguably makes sense.
 void* pp = (decltype(nullptr))0; // expected-warning{{zero as null pointer constant}}
 void* pp2 = static_cast<decltype(nullptr)>(0); // expected-warning{{zero as null pointer constant}}
+
+// Shouldn't warn.
+struct pr34362 { operator int*() { return nullptr; } };
+void pr34362_func() { if (nullptr == pr34362()) {} }

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