[PATCH] D32519: [Sema] Avoid using a null type pointer (fixes PR32750)

[Vedant Kumar via Phabricator via cfe-commits]

vsk created this revision.

isMicrosoftMissingTypename() uses a Type pointer without first checking         
                                                                              
that it's non-null. PR32750 reports a case where the pointer is in fact         
                                                                              
null. This patch adds in a defensive check and a regression test.


https://reviews.llvm.org/D32519

Files:
  lib/Sema/SemaDecl.cpp
  test/SemaCXX/MicrosoftExtensions.cpp


Index: test/SemaCXX/MicrosoftExtensions.cpp
===================================================================
--- test/SemaCXX/MicrosoftExtensions.cpp
+++ test/SemaCXX/MicrosoftExtensions.cpp
@@ -2,6 +2,7 @@
 // RUN: %clang_cc1 -std=c++98 %s -triple i686-pc-win32 -fsyntax-only 
-Wmicrosoft -Wc++11-extensions -Wno-long-long -verify -fms-extensions 
-fexceptions -fcxx-exceptions -DTEST1
 // RUN: %clang_cc1 -std=c++11 %s -triple i686-pc-win32 -fsyntax-only 
-Wmicrosoft -Wc++11-extensions -Wno-long-long -verify -fms-extensions 
-fexceptions -fcxx-exceptions -DTEST1
 // RUN: %clang_cc1 %s -triple i686-pc-win32 -fsyntax-only -Wmicrosoft 
-Wc++11-extensions -Wno-long-long -verify -fexceptions -fcxx-exceptions -DTEST2
+// RUN: %clang_cc1 %s -triple i686-pc-win32 -fsyntax-only -std=c++14 
-fms-compatibility -verify -DTEST3
 
 #if TEST1
 
@@ -508,6 +509,13 @@
 // Check that __unaligned is not recognized if MS extensions are not enabled
 typedef char __unaligned *aligned_type; // expected-error {{expected ';' after 
top level declarator}}
 
+#elif TEST3
+
+namespace PR32750 {
+template<typename T> struct A {};
+template<typename T> struct B : A<A<T> > { A<T>::C::D d; }; // expected-error 
{{missing 'typename' prior to dependent type name 'A<T>::C::D'}}
+}
+
 #else
 
 #error Unknown test mode
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -615,7 +615,7 @@
 
     CXXRecordDecl *RD = cast<CXXRecordDecl>(CurContext);
     for (const auto &Base : RD->bases())
-      if (Context.hasSameUnqualifiedType(QualType(Ty, 1), Base.getType()))
+      if (Ty && Context.hasSameUnqualifiedType(QualType(Ty, 1), 
Base.getType()))
         return true;
     return S->isFunctionPrototypeScope();
   }



Index: test/SemaCXX/MicrosoftExtensions.cpp
===================================================================
--- test/SemaCXX/MicrosoftExtensions.cpp
+++ test/SemaCXX/MicrosoftExtensions.cpp
@@ -2,6 +2,7 @@
 // RUN: %clang_cc1 -std=c++98 %s -triple i686-pc-win32 -fsyntax-only -Wmicrosoft -Wc++11-extensions -Wno-long-long -verify -fms-extensions -fexceptions -fcxx-exceptions -DTEST1
 // RUN: %clang_cc1 -std=c++11 %s -triple i686-pc-win32 -fsyntax-only -Wmicrosoft -Wc++11-extensions -Wno-long-long -verify -fms-extensions -fexceptions -fcxx-exceptions -DTEST1
 // RUN: %clang_cc1 %s -triple i686-pc-win32 -fsyntax-only -Wmicrosoft -Wc++11-extensions -Wno-long-long -verify -fexceptions -fcxx-exceptions -DTEST2
+// RUN: %clang_cc1 %s -triple i686-pc-win32 -fsyntax-only -std=c++14 -fms-compatibility -verify -DTEST3
 
 #if TEST1
 
@@ -508,6 +509,13 @@
 // Check that __unaligned is not recognized if MS extensions are not enabled
 typedef char __unaligned *aligned_type; // expected-error {{expected ';' after top level declarator}}
 
+#elif TEST3
+
+namespace PR32750 {
+template<typename T> struct A {};
+template<typename T> struct B : A<A<T> > { A<T>::C::D d; }; // expected-error {{missing 'typename' prior to dependent type name 'A<T>::C::D'}}
+}
+
 #else
 
 #error Unknown test mode
Index: lib/Sema/SemaDecl.cpp
===================================================================
--- lib/Sema/SemaDecl.cpp
+++ lib/Sema/SemaDecl.cpp
@@ -615,7 +615,7 @@
 
     CXXRecordDecl *RD = cast<CXXRecordDecl>(CurContext);
     for (const auto &Base : RD->bases())
-      if (Context.hasSameUnqualifiedType(QualType(Ty, 1), Base.getType()))
+      if (Ty && Context.hasSameUnqualifiedType(QualType(Ty, 1), Base.getType()))
         return true;
     return S->isFunctionPrototypeScope();
   }

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