MS ABI: Allow a nullptr_t exception to be caught by void * catch handler

A nullptr exception object can be caught by any pointer type catch
handler.  However, it is not possible to express this in the exception
info for the MS ABI.  As a middle ground, allow such exception objects
to be caught with pointer-to-void catch handlers.

llvm-svn: 232069

2 files changed, 16 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index 3bc9f64fe4b..1f5d678f4d6 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -3490,6 +3490,17 @@ llvm::GlobalVariable *MicrosoftCXXABI::getCatchableTypeArray(QualType T) {
   if (IsPointer)
     CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
 
+  // C++14 [except.handle]p3:
+  //   A handler is a match for an exception object of type E if [...]
+  //     - the handler is of type cv T or const T& where T is a pointer or
+  //       pointer to member type and E is std::nullptr_t.
+  //
+  // We cannot possibly list all possible pointer types here, making this
+  // implementation incompatible with the standard.  However, MSVC includes an
+  // entry for pointer-to-void in this case.  Let's do the same.
+  if (T->isNullPtrType())
+    CatchableTypes.insert(getCatchableType(getContext().VoidPtrTy));
+
   uint32_t NumEntries = CatchableTypes.size();
   llvm::Type *CTType =
       getImageRelativeType(getCatchableTypeType()->getPointerTo());
diff --git a/clang/test/CodeGenCXX/microsoft-abi-throw.cpp b/clang/test/CodeGenCXX/microsoft-abi-throw.cpp
index 0548eb44dd6..8e7231ba634 100644
--- a/clang/test/CodeGenCXX/microsoft-abi-throw.cpp
+++ b/clang/test/CodeGenCXX/microsoft-abi-throw.cpp
@@ -15,6 +15,7 @@
 // CHECK-DAG: @"_CT??_R0?AUDefault@@@8??_ODefault@@QAEXAAU0@@Z1" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 0, i8* bitcast (%rtti.TypeDescriptor13* @"\01??_R0?AUDefault@@@8" to i8*), i32 0, i32 -1, i32 0, i32 1, i8* bitcast (void (%struct.Default*, %struct.Default*)* @"\01??_ODefault@@QAEXAAU0@@Z" to i8*) }, section ".xdata", comdat
 // CHECK-DAG: @"_CT??_R0?AUVariadic@@@8??_OVariadic@@QAEXAAU0@@Z1" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 0, i8* bitcast (%rtti.TypeDescriptor14* @"\01??_R0?AUVariadic@@@8" to i8*), i32 0, i32 -1, i32 0, i32 1, i8* bitcast (void (%struct.Variadic*, %struct.Variadic*)* @"\01??_OVariadic@@QAEXAAU0@@Z" to i8*) }, section ".xdata", comdat
 // CHECK-DAG: @"_CT??_R0?AUTemplateWithDefault@@@8??$?_OH@TemplateWithDefault@@QAEXAAU0@@Z1" = linkonce_odr unnamed_addr constant %eh.CatchableType { i32 0, i8* bitcast (%rtti.TypeDescriptor25* @"\01??_R0?AUTemplateWithDefault@@@8" to i8*), i32 0, i32 -1, i32 0, i32 1, i8* bitcast (void (%struct.TemplateWithDefault*, %struct.TemplateWithDefault*)* @"\01??$?_OH@TemplateWithDefault@@QAEXAAU0@@Z" to i8*) }, section ".xdata", comdat
+// CHECK-DAG: @"_CTA2$$T" = linkonce_odr unnamed_addr constant %eh.CatchableTypeArray.2 { i32 2, [2 x %eh.CatchableType*] [%eh.CatchableType* @"_CT??_R0$$T@84", %eh.CatchableType* @"_CT??_R0PAX@84"] }, section ".xdata", comdat
 
 
 struct N { ~N(); };
@@ -87,3 +88,7 @@ struct TemplateWithDefault {
 void j(TemplateWithDefault &twd) {
   throw twd;
 }
+
+void h() {
+  throw nullptr;
+}