r197164 - Switch to the new MingW ABI.

[Reid Kleckner]

Summarizing a conversation on IRC, I think we can keep this in for now and
try to improve diagnostics other ways.

MSVC *always* includes the calling convention in its diagnostics, so unless
we have the smarts to know it's irrelevant, I think we should keep it for
the time being.

There's a few things we can do:

1. Thread an ASTContext into TypePrinter, so it knows the default method
CC.  Then it should suppress it, but probably *only* on member function
pointer types, since it's implied.  Anywhere else it might be important.

2. Strengthen the test patterns to match only __attribute__((thiscall)) if
you're worried about overmatching qualifiers

3. Print "void (__thiscall identifier)()" instead of "void identifier()
__attribute__((thiscall))" to reduce the diagnostic length.  That keyword
only works with -fms-extensions, though, which I believe is off for mingw
by default.


On Thu, Dec 12, 2013 at 9:02 AM, Rafael Espíndola <
rafael.espindola at gmail.com> wrote:

> > Added:
> >     cfe/trunk/test/CodeGenCXX/mingw-new-abi.cpp
> > Modified:
> >     cfe/trunk/docs/ReleaseNotes.rst
> >     cfe/trunk/lib/AST/ItaniumCXXABI.cpp
> >     cfe/trunk/test/CXX/class.access/p6.cpp
> >     cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p1.cpp
> >     cfe/trunk/test/CXX/expr/expr.const/p3-0x.cpp
> >     cfe/trunk/test/CXX/expr/expr.mptr.oper/p5.cpp
> >     cfe/trunk/test/CXX/expr/expr.mptr.oper/p6-0x.cpp
> >     cfe/trunk/test/CXX/expr/expr.prim/expr.prim.lambda/blocks.mm
> >     cfe/trunk/test/CXX/expr/expr.unary/expr.unary.op/p4.cpp
> >     cfe/trunk/test/CXX/temp/temp.arg/temp.arg.nontype/p5.cpp
> >
> >
> > These frontend tests really benefit from having precise matches:
> >
> > Consider a change like this:
> >
> >
> > -int n = Val<bool, &S::operator int>::value; // expected-error
> {{conversion
> > from 'int (S::*)() const' to 'bool' is not allowed in a converted
> constant
> > expression}}
> > +int n = Val<bool, &S::operator int>::value; // expected-error-re
> > {{conversion from 'int (S::*)() {{.*}}const' to 'bool' is not allowed in
> a
> > converted constant expression}}
> >
> >
> > Now there's no testing at all for the qualifiers. Not good.
> >
> > They've had stable output across several OS and hardware configurations
> and
> > major versions for years.
> >
> > So if an ABI point release switch on MinGW suddenly caused dozens of
> stable
> > tests to break, I'd say that's a problem with the patch, rather than a
> case
> > for editing all the tests.
> >
> > It's best to revert this until the pretty printer is fixed to display
> > calling conventions only if they differ from the platform default.
> >
>
> I am happy to revert the test changes and add a -triple instead for now.
>
> I will just let Reid comment on it since he suggested relaxing the tests.
>
> Cheers,
> Rafael
>
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