Building parrot with clang

(I'm sending this to both the parrot and the clang list since I have no
ideawho will be involved in fixing some of the things)

Today I tried to build parrot with clang on linux/amd64.
(Used versions: parrot r39691, llvm r73859, clang r73854)
I configured parrot with
perl Configure.pl --cc=$path/to/clang_executable/clang
Configure finished fine, however during 'make' there was an error:

./src/pmc/env.pmc:28:14: fatal error: 'crt_externs.h' file not found
# include <crt_externs.h>
             ^
1 diagnostic generated.
make: *** [src/pmc/env.o] Error 1

The offending portion of env.pmc looks like this:
#ifndef WIN32
# ifdef __APPLE_CC__
# include <crt_externs.h>
# define environ (*_NSGetEnviron())
# else /* !__APPLE_CC__ */
extern char **environ;
# endif /* __APPLE_CC__ */
#endif /* !WIN32 */

So it seems that parrot expects the presence of a crt_externs.h file if
__APPLE_CC__ is set, while clang provides the latter but not the former.

(I've submitted that as a bug report here:
<https://trac.parrot.org/parrot/ticket/782&gt;\)

Configuring parrot with --ccflags=-U__APPLE_CC__ works around this,
leading to
the next failure, apparently in the linking step:

src/pmc/bignum.o: In function `__gmpz_abs':
/usr/include/gmp.h:1611: multiple definition of `__gmpz_abs'
src/pmc/bigint.o:/usr/include/gmp.h:1611: first defined here
src/pmc/bignum.o: In function `__gmpz_fits_uint_p':
/usr/include/gmp.h:1637: multiple definition of `__gmpz_fits_uint_p'
src/pmc/bigint.o:/usr/include/gmp.h:1637: first defined here
src/pmc/bignum.o: In function `__gmpz_fits_ulong_p':
/usr/include/gmp.h:1648: multiple definition of `__gmpz_fits_ulong_p'
src/pmc/bigint.o:/usr/include/gmp.h:1648: first defined here
src/pmc/bignum.o: In function `__gmpz_fits_ushort_p':
...
collect2: ld returned 1 exit status
make: *** [blib/lib/libparrot.so.1.3.0] Error 1

I have no idea if parrot or clang is to blame here.
Also adding --without-gmp to parrot's Configure.pl works around this one
too,allowing me to build parrot with clang. Running 'make tests' shows
that it passes all standard tests except one (test 4 in t/op/gc).

I hope this is of interest,
Moritz

(I'm sending this to both the parrot and the clang list since I have no
ideawho will be involved in fixing some of the things)

Today I tried to build parrot with clang on linux/amd64.
(Used versions: parrot r39691, llvm r73859, clang r73854)
I configured parrot with
perl Configure.pl --cc=$path/to/clang_executable/clang
Configure finished fine, however during 'make' there was an error:

./src/pmc/env.pmc:28:14: fatal error: 'crt_externs.h' file not found
# include <crt_externs.h>
            ^
1 diagnostic generated.
make: *** [src/pmc/env.o] Error 1

The offending portion of env.pmc looks like this:
#ifndef WIN32
# ifdef __APPLE_CC__
# include <crt_externs.h>
# define environ (*_NSGetEnviron())
# else /* !__APPLE_CC__ */
extern char **environ;
# endif /* __APPLE_CC__ */
#endif /* !WIN32 */

So it seems that parrot expects the presence of a crt_externs.h file if
__APPLE_CC__ is set, while clang provides the latter but not the former.

I think this is a clang bug. __APPLE_CC__ should not be set on linux.

Configuring parrot with --ccflags=-U__APPLE_CC__ works around this,
leading to
the next failure, apparently in the linking step:

What do the definitions of __gmpz_abs and friends look like? Can you paste them? One difference between clang and gcc is that clang defaults to c99 mode, gcc defaults to c89 mode. Does it work if you compile with -std=gnu89?

-Chris

Chris Lattner wrote:

(I'm sending this to both the parrot and the clang list since I have
no
ideawho will be involved in fixing some of the things)

Today I tried to build parrot with clang on linux/amd64.
(Used versions: parrot r39691, llvm r73859, clang r73854)
I configured parrot with
perl Configure.pl --cc=$path/to/clang_executable/clang
Configure finished fine, however during 'make' there was an error:

./src/pmc/env.pmc:28:14: fatal error: 'crt_externs.h' file not found
# include <crt_externs.h>
            ^
1 diagnostic generated.
make: *** [src/pmc/env.o] Error 1

The offending portion of env.pmc looks like this:
#ifndef WIN32
# ifdef __APPLE_CC__
# include <crt_externs.h>
# define environ (*_NSGetEnviron())
# else /* !__APPLE_CC__ */
extern char **environ;
# endif /* __APPLE_CC__ */
#endif /* !WIN32 */

So it seems that parrot expects the presence of a crt_externs.h file
if
__APPLE_CC__ is set, while clang provides the latter but not the
former.

I think this is a clang bug. __APPLE_CC__ should not be set on linux.

Ok, thanks for the feedback.

Configuring parrot with --ccflags=-U__APPLE_CC__ works around this,
leading to
the next failure, apparently in the linking step:

What do the definitions of __gmpz_abs and friends look like? Can you
paste them?

From /usr/include/gmp.h:

/* The following are provided as inlines where possible, but always exist as
   library functions too, for binary compatibility.

   Within gmp itself this inlining generally isn't relied on, since it
   doesn't get done for all compilers, whereas if something is worth
   inlining then it's worth arranging always.

   There are two styles of inlining here. When the same bit of code is
   wanted for the inline as for the library version, then __GMP_FORCE_foo
   arranges for that code to be emitted and the __GMP_EXTERN_INLINE
   directive suppressed, eg. mpz_fits_uint_p. When a different bit of code
   is wanted for the inline than for the library version, then
   __GMP_FORCE_foo arranges the inline to be suppressed, eg. mpz_abs. */

#if defined (__GMP_EXTERN_INLINE) && ! defined (__GMP_FORCE_mpz_abs)
__GMP_EXTERN_INLINE void
mpz_abs (mpz_ptr __gmp_w, mpz_srcptr __gmp_u)
{
  if (__gmp_w != __gmp_u)
    mpz_set (__gmp_w, __gmp_u);
  __gmp_w->_mp_size = __GMP_ABS (__gmp_w->_mp_size);
}
#endif

Neither __GMP_EXTERN_INLINE nor __GMP_FORCE_mpz_abs appear anywhere in
the parrot source tree

__GMP_EXTERN_INLINE is defined thusly:

#ifdef __GNUC__
#if (defined __GNUC_STDC_INLINE__) || (__GNUC__ == 4 && __GNUC_MINOR__ == 2)
#define __GMP_EXTERN_INLINE extern __inline__ __attribute__
((__gnu_inline__))
#else
#define __GMP_EXTERN_INLINE extern __inline__
#endif
#define __GMP_INLINE_PROTOTYPES 1
#endif

One difference between clang and gcc is that clang
defaults to c99 mode, gcc defaults to c89 mode. Does it work if you
compile with -std=gnu89?

No, same result.

Cheers,
Moritz

(I'm sending this to both the parrot and the clang list since I have no
ideawho will be involved in fixing some of the things)

Today I tried to build parrot with clang on linux/amd64.
(Used versions: parrot r39691, llvm r73859, clang r73854)
I configured parrot with
perl Configure.pl --cc=$path/to/clang_executable/clang
Configure finished fine, however during 'make' there was an error:

[bizarre APPLE_CC error omitted ]

Configuring parrot with --ccflags=-U__APPLE_CC__ works around this,
leading to
the next failure, apparently in the linking step:

src/pmc/bignum.o: In function `__gmpz_abs':
/usr/include/gmp.h:1611: multiple definition of `__gmpz_abs'
src/pmc/bigint.o:/usr/include/gmp.h:1611: first defined here

I have no idea if parrot or clang is to blame here.

One thing to watch out for: Parrot's Configure.pl is very bad at guessing
the correct programs and flags to use if you try to build parrot with any
compiler other than the one used to build the supporting perl 5. I
strongly encourage you to run

  perl Configure.pl --cc=$path/to/clang_executable/clang --ask

to step through the questions to see what programs and flags Configure.pl
will choose, and to allow you to choose the correct ones instead. You can
then note your answers and re-run Configure.pl with all the correct
settings.

I fixed this in r73934.

-Chris