[PATCH] D19654: PR27132: Proper mangling for __unaligned qualifier (now with PR27367 fixed)

[David Majnemer via cfe-commits]

majnemer added inline comments.

================
Comment at: lib/AST/MicrosoftMangle.cpp:1583-1584
@@ -1579,2 +1582,4 @@
   case QMM_Result:
+    // Presence of __unaligned qualifier shouldn't affect mangling here.
+    Quals.removeUnaligned();
     if ((!IsPointer && Quals) || isa<TagType>(T)) {
----------------
majnemer wrote:
> rnk wrote:
> > majnemer wrote:
> > > andreybokhanko wrote:
> > > > majnemer wrote:
> > > > > andreybokhanko wrote:
> > > > > > Done. Test added.
> > > > > Hmm, can you give a concrete example why we need this line?
> > > > Sure. An example is:
> > > > 
> > > > __unaligned int unaligned_foo3() { return 0; }
> > > > 
> > > > MS mangles it as
> > > > 
> > > > ?unaligned_foo3@@YAHXZ
> > > > 
> > > > However, if __unaligned is taken into account, "if ((!IsPointer && Quals) || isa<TagType>(T))" computes to true and clang adds "?A", resulting to
> > > > 
> > > > ?unaligned_foo3@@YA?AHXZ
> > > > 
> > > > Yours,
> > > > Andrey
> > > > 
> > > Wait, I thought __unaligned can only apply to pointer types.  Is this not so?!
> > > Does `__unaligned int x;` really keep it's `__unaligned` qualifier?
> > Yeah it does:
> >   $ cat t.cpp
> >   __unaligned int x;
> >   $ cl -nologo -c t.cpp && dumpbin /symbols t.obj  | grep ?x
> >   t.cpp
> >   008 00000000 SECT3  notype       External     | ?x@@3HFA (int __unaligned x)
> Woah.  So if you do:
> 
> > __unaligned int unaligned_foo3() { return 0; }
> > auto z = foo3();
> 
> How is `z` mangled?
`z` is mangled without the qualifiers.  In fact:

```
__unaligned int unaligned_foo3() { return 0; }
__unaligned int z;
auto z = unaligned_foo3();
```

Is an error:


> x.cpp(3): error C2373: 'z': redefinition; different type modifiers
> x.cpp(2): note: see declaration of 'z'

Do we have comparable behavior?


http://reviews.llvm.org/D19654