[-cxx-abi microsoft] Properly mangle enums

While testing our ability to mangle large constants (PR18175), I
incidentally discovered that we did not properly mangle enums correctly.

Previously, we would append the width of the enum in bytes after the
type-tag differentiator.

This would mean "enum : short" would be mangled as 'W2' while "enum :
char" would be mangled as 'W1'.  Upon testing this with several versions
of MSVC, I found that this did not match their behavior: they always use
'W4'.

N.B.  Quick testing uncovered that undname allows different numbers to
follow the 'W' in the following way:

'W0' -> "enum char"
'W1' -> "enum unsigned char"
'W2' -> "enum short"
'W3' -> "enum unsigned short"
'W4' -> "enum"
'W5' -> "enum unsigned int"
'W6' -> "enum long"
'W7' -> "enum unsigned long"

However this scheme appears abandoned, I cannot get MSVC to trigger it.
Furthermore, it's incomplete: it doesn't handle "bool" or "long long".

llvm-svn: 196752

1 files changed, 2 insertions, 4 deletions

diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index ae4fbf7f048..0599d8af813 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -1472,7 +1472,7 @@ void MicrosoftCXXNameMangler::mangleType(const UnresolvedUsingType *T,
 // <union-type>  ::= T <name>
 // <struct-type> ::= U <name>
 // <class-type>  ::= V <name>
-// <enum-type>   ::= W <size> <name>
+// <enum-type>   ::= W4 <name>
 void MicrosoftCXXNameMangler::mangleType(const EnumType *T, SourceRange) {
   mangleType(cast<TagType>(T)->getDecl());
 }
@@ -1492,9 +1492,7 @@ void MicrosoftCXXNameMangler::mangleType(const TagDecl *TD) {
       Out << 'V';
       break;
     case TTK_Enum:
-      Out << 'W';
-      Out << getASTContext().getTypeSizeInChars(
-                cast<EnumDecl>(TD)->getIntegerType()).getQuantity();
+      Out << "W4";
       break;
   }
   mangleName(TD);