Ping*2 PATCH: testcase for "ICE for unknown parameter to constexpr'd switch-statement, PR113545"

[Hans-Peter Nilsson <hp@axis.com>]

> From: Hans-Peter Nilsson <hp@axis.com>
> Date: Tue, 30 Jan 2024 06:18:45 +0100

> Ping for the xfailed testsuite patch below the review
> (actual constexpr.cc patch to be handled separately):

Ping*2.  Again, this is for the xfailed test-case only.

> 
> > From: Hans-Peter Nilsson <hp@axis.com>
> > Date: Tue, 23 Jan 2024 05:55:00 +0100
> > 
> > > Date: Mon, 22 Jan 2024 14:33:59 -0500
> > > From: Marek Polacek <polacek@redhat.com>
> > 
> > > The problem seems to be more about conversion so g++.dg/conversion/reinterpret5.C
> > > or g++.dg/cpp0x/constexpr-reinterpret3.C seems more appropriate.
> > > 
> > > > @@ -0,0 +1,49 @@
> > > 
> > > Please add
> > > 
> > > PR c++/113545
> > 
> > > > +  unsigned const char c = swbar(reinterpret_cast<__UINTPTR_TYPE__>(&foo));
> > > > +  xyzzy(c);
> > > > +  unsigned const char d = ifbar(reinterpret_cast<__UINTPTR_TYPE__>(&foo));
> > > 
> > > I suppose we should also test a C-style cast (which leads to a reinterpret_cast
> > > in this case).
> > > 
> > > Maybe check we get an error when c/d are constexpr (that used to ICE).
> > 
> > Like this?  Not sure about the value of that variant, but here goes.
> > 
> > I checked that these behave as expected (xfail as ICE properly) without the
> > previosly posted patch to cp/constexpr.cc and XPASS with it applied.
> > 
> > Ok to commit?
> > 
> > -- >8 --
> > Subject: [PATCH] c++: testcases for PR113545 (constexpr with switch and
> >  passing non-constexpr parameter)
> > 
> > gcc/testsuite:
> > 	PR c++/113545
> > 	* g++.dg/cpp0x/constexpr-reinterpret3.C,
> > 	g++.dg/cpp0x/constexpr-reinterpret4.C: New tests.
> > ---
> >  .../g++.dg/cpp0x/constexpr-reinterpret3.C     | 55 +++++++++++++++++++
> >  .../g++.dg/cpp0x/constexpr-reinterpret4.C     | 54 ++++++++++++++++++
> >  2 files changed, 109 insertions(+)
> >  create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-reinterpret3.C
> >  create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-reinterpret4.C
> > 
> > diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-reinterpret3.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-reinterpret3.C
> > new file mode 100644
> > index 000000000000..319cc5e8bee9
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-reinterpret3.C
> > @@ -0,0 +1,55 @@
> > +// PR c++/113545
> > +// { dg-do run { target c++11 } }
> > +// { dg-ice "PR112545 - constexpr function with switch called for reinterpret_cast" }
> > +
> > +char foo;
> > +
> > +// This one caught a call to gcc_unreachable in
> > +// cp/constexpr.cc:label_matches, when passed a convert_expr from the
> > +// cast in the call.
> > +constexpr unsigned char swbar(__UINTPTR_TYPE__ baz)
> > +{
> > +  switch (baz)
> > +    {
> > +    case 13:
> > +      return 11;
> > +    case 14:
> > +      return 78;
> > +    case 2048:
> > +      return 13;
> > +    default:
> > +      return 42;
> > +    }
> > +}
> > +
> > +// For reference, the equivalent* if-statements.
> > +constexpr unsigned char ifbar(__UINTPTR_TYPE__ baz)
> > +{
> > +  if (baz == 13)
> > +    return 11;
> > +  else if (baz == 14)
> > +    return 78;
> > +  else if (baz == 2048)
> > +    return 13;
> > +  else
> > +    return 42;
> > +}
> > +
> > +__attribute__ ((__noipa__))
> > +void xyzzy(int x)
> > +{
> > +  if (x != 42)
> > +    __builtin_abort ();
> > +}
> > +
> > +int main()
> > +{
> > +  unsigned const char c = swbar(reinterpret_cast<__UINTPTR_TYPE__>(&foo));
> > +  xyzzy(c);
> > +  unsigned const char d = ifbar(reinterpret_cast<__UINTPTR_TYPE__>(&foo));
> > +  xyzzy(d);
> > +  unsigned const char e = swbar((__UINTPTR_TYPE__) &foo);
> > +  xyzzy(e);
> > +  unsigned const char f = ifbar((__UINTPTR_TYPE__) &foo);
> > +  xyzzy(f);
> > +}
> > diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-reinterpret4.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-reinterpret4.C
> > new file mode 100644
> > index 000000000000..4d0fdf2c0a78
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-reinterpret4.C
> > @@ -0,0 +1,54 @@
> > +// PR c++/113545
> > +// { dg-do compile { target c++11 } }
> > +
> > +char foo;
> > +
> > +// This one caught a call to gcc_unreachable in
> > +// cp/constexpr.cc:label_matches, when passed a convert_expr from the
> > +// cast in the call.
> > +constexpr unsigned char swbar(__UINTPTR_TYPE__ baz)
> > +{
> > +  switch (baz)
> > +    {
> > +    case 13:
> > +      return 11;
> > +    case 14:
> > +      return 78;
> > +    case 2048:
> > +      return 13;
> > +    default:
> > +      return 42;
> > +    }
> > +}
> > +
> > +// For reference, the equivalent* if-statements.
> > +constexpr unsigned char ifbar(__UINTPTR_TYPE__ baz)
> > +{
> > +  if (baz == 13)
> > +    return 11;
> > +  else if (baz == 14)
> > +    return 78;
> > +  else if (baz == 2048)
> > +    return 13;
> > +  else
> > +    return 42;
> > +}
> > +
> > +__attribute__ ((__noipa__))
> > +void xyzzy(int x)
> > +{
> > +  if (x != 42)
> > +    __builtin_abort ();
> > +}
> > +
> > +int main()
> > +{
> > +  unsigned constexpr char c = swbar(reinterpret_cast<__UINTPTR_TYPE__>(&foo)); // { dg-error "conversion from pointer type" }
> > +  xyzzy(c);
> > +  unsigned constexpr char d = ifbar(reinterpret_cast<__UINTPTR_TYPE__>(&foo)); // { dg-error "conversion from pointer type" }
> > +  xyzzy(d);
> > +  unsigned constexpr char e = swbar((__UINTPTR_TYPE__) &foo); // { dg-error "conversion from pointer type" }
> > +  xyzzy(e);
> > +  unsigned constexpr char f = ifbar((__UINTPTR_TYPE__) &foo); // { dg-error "conversion from pointer type" }
> > +  xyzzy(f);
> > +}
> > -- 
> > 2.30.2
> > 
>