From tauner@technikum-wien.at

Hi,

I have used h2xs for the first time today to start the creation of a
Perl package based on a small C library. make failed to build it
apparently due to the usage of a bool type for a parameter in one of
the library's exported functions resulting in

error​: ‘arg1’ undeclared (first use in this function)
  RETVAL = dap_poll(context, arg1);

The generated code in the .xs is​:

XS_EUPXS(XS_function_name)
{
  dVAR; dXSARGS;
  if (items != 2)
  croak_xs_usage(cv, "context, arg1");
  {
  struct some_context * context;
  int RETVAL;
  dXSTARG;
[...]

Note that there is no variable definition for "arg1" (whose name is
actually made up by h2xs apparently - in the library it is called wait).

When I change the library to use int instead of bool (or _Bool) then
the parameter is handled correctly (NB​: "wait" in the croak_xs_usage()
call)​:

XS_EUPXS(XS_function_name)
{
  dVAR; dXSARGS;
  if (items != 2)
  croak_xs_usage(cv, "context, wait");
  {
  struct some_context * context;
  int wait = (int)SvIV(ST(1))
;
  int RETVAL;
  dXSTARG;
[...]

_Bool is a C type introduced in C99, bool is a typedef declared by
stdbool.h also from C99 and nothing fancy at all. I am using h2xs from
ubuntu's Perl 5.22.1 but I could not find any hint on bool support in
h2xs in Perl git thus I am reporting this here.

KR
--
Dipl.-Ing. Stefan Tauner
Research and Development
Embedded Systems Department

University of Applied Sciences Technikum Wien
Hoechstaedtplatz 6, 1200 Vienna, Austria
T​: +43 1 333 40 77-316
E​: stefan.tauner@​technikum-wien.at
I​: embsys.technikum-wien.at
I​: www.technikum-wien.at

From @iabyn

On Fri, Dec 23, 2016 at 07​:10​:27AM -0800, Stefan Tauner wrote​:

I have used h2xs for the first time today to start the creation of a
Perl package based on a small C library. make failed to build it
apparently due to the usage of a bool type for a parameter in one of
the library's exported functions resulting in

error​: ‘arg1’ undeclared (first use in this function)

Can you show us​:

1) the command-line your are invoking h2xs with;
2) the relevant declarations(s) from the .h file (or even better,
attach a short stripped down and self-contained .h file that reproduces
the problem);
2) attach the output of 'perl -V' for the perl used to execute h2xs.

Thanks.

--
The Enterprise's efficient long-range scanners detect a temporal vortex
distortion in good time, allowing it to be safely avoided via a minor
course correction.
  -- Things That Never Happen in "Star Trek" #21

The RT System itself - Status changed from 'new' to 'open'

From tauner@technikum-wien.at

On Sun, 25 Dec 2016 11​:21​:10 -0800
"Dave Mitchell via RT" <perlbug-followup@​perl.org> wrote​:

On Fri, Dec 23, 2016 at 07​:10​:27AM -0800, Stefan Tauner wrote​:

I have used h2xs for the first time today to start the creation of a
Perl package based on a small C library. make failed to build it
apparently due to the usage of a bool type for a parameter in one of
the library's exported functions resulting in

error​: ‘arg1’ undeclared (first use in this function)

Can you show us​:

1) the command-line your are invoking h2xs with;

h2xs -x booltest.h
So this might be a bug in C​::Scan (which I have installed via cpanm
from HVDS/C-Scan-0.74)?

2) the relevant declarations(s) from the .h file (or even better,
attach a short stripped down and self-contained .h file that
reproduces the problem);

booltest.h​:

  #include <stdbool.h>
  void h2xs(bool b);

With a trivial implementation in booltest.c​:

  #include "booltest.h"
  void h2xs(bool b) {
  (void)b;
  }

However, the same thing works fine with _Bool instead of bool+stdbool.h.

2) attach the output of 'perl -V' for the perl used to execute h2xs.

See attached perl.V

KR
--
Dipl.-Ing. Stefan Tauner
Research and Development
Embedded Systems Department

University of Applied Sciences Technikum Wien
Hoechstaedtplatz 6, 1200 Vienna, Austria
T​: +43 1 333 40 77-316
E​: stefan.tauner@​technikum-wien.at
I​: embsys.technikum-wien.at
I​: www.technikum-wien.at

From tauner@technikum-wien.at

perl.V

From @jkeenan

On Wed, 28 Dec 2016 06​:00​:21 GMT, tauner@​technikum-wien.at wrote​:

h2xs -x booltest.h
So this might be a bug in C​::Scan (which I have installed via cpanm
from HVDS/C-Scan-0.74)?

What happens if you do not use the '-x' option and thereby avoid C​::Scan?

(When I did that, 'make' completed -- but since I've rarely attempted to write XS I don't know whether that's meaningful or not.)

Thank you very much.

--
James E Keenan (jkeenan@​cpan.org)

From @iabyn

On Wed, Dec 28, 2016 at 05​:37​:04AM -0800, James E Keenan via RT wrote​:

On Wed, 28 Dec 2016 06​:00​:21 GMT, tauner@​technikum-wien.at wrote​:

h2xs -x booltest.h
So this might be a bug in C​::Scan (which I have installed via cpanm
from HVDS/C-Scan-0.74)?

What happens if you do not use the '-x' option and thereby avoid C​::Scan?

(When I did that, 'make' completed -- but since I've rarely attempted to write XS I don't know whether that's meaningful or not.)

Thank you very much.

When foo,h contains this​:

  #include <stdbool.h>
  void h2xs(bool b);

then h2xs -x foo.h, via C​::Scan, is generating an XS file that looks like​:

  void
  h2xs(arg0)

which is being converted into the C code

  XS_EUPXS(XS_Foo_h2xs); /* prototype to pass -Wmissing-prototypes */
  XS_EUPXS(XS_Foo_h2xs)
  {
  dVAR; dXSARGS;
  if (items != 1)
  croak_xs_usage(cv, "arg0");
  {

  h2xs(arg0);
  }
  XSRETURN_EMPTY;
  }

The issues seem to be that

1) h2xs and/or C​::Scan isn't including the variable type for arg0 in the
generated XS; I assume that it should have output​:

  void
  h2xs(bool arg0)

2) that ExtUtils/xsubpp isn't seeing that as an error and is instead
converting it onto invalid C code, by not including the line​:

  bool arg0 = (bool)SvTRUE(ST(0))

Does anyone here more familiar with XS want to comment?

--
Indomitable in retreat, invincible in advance, insufferable in victory
  -- Churchill on Montgomery

From tauner@technikum-wien.at

On Wed, 28 Dec 2016 05​:37​:04 -0800
"James E Keenan via RT" <perlbug-followup@​perl.org> wrote​:

On Wed, 28 Dec 2016 06​:00​:21 GMT, tauner@​technikum-wien.at wrote​:

h2xs -x booltest.h
So this might be a bug in C​::Scan (which I have installed via cpanm
from HVDS/C-Scan-0.74)?

What happens if you do not use the '-x' option and thereby avoid
C​::Scan?

(When I did that, 'make' completed -- but since I've rarely attempted
to write XS I don't know whether that's meaningful or not.)

Yes, then it succeeds because the functions are not wrapped at all :)
I don't know if that's on purpose or a bug, but I presume the former.
I have no idea how it can be used without that though. Maybe to just
prepare a skeleton package...

KR
--
Dipl.-Ing. Stefan Tauner
Research and Development
Embedded Systems Department

University of Applied Sciences Technikum Wien
Hoechstaedtplatz 6, 1200 Vienna, Austria
T​: +43 1 333 40 77-316
E​: stefan.tauner@​technikum-wien.at
I​: embsys.technikum-wien.at
I​: www.technikum-wien.at

From @Leont

On Fri, Dec 23, 2016 at 4​:10 PM, Stefan Tauner <perlbug-followup@​perl.org>
wrote

_Bool is a C type introduced in C99, bool is a typedef declared by
stdbool.h also from C99 and nothing fancy at all. I am using h2xs from
ubuntu's Perl 5.22.1 but I could not find any hint on bool support in
h2xs in Perl git thus I am reporting this here.

_Bool is indeed a C99 built-in type, but bool is a *macro* to _Bool, not a
typedef. This apparently confuses h2xs/C​::Scan, which I don't think is
entirely unreasonable given the alternative.

I would recommend using _Bool instead of bool, that seems to generate
sensible XS if you add a one line typemap file to your distribution
containing
_Bool T_BOOL

Leon

From @hvds

On Wed, 28 Dec 2016 07​:13​:36 -0800, davem wrote​:

On Wed, Dec 28, 2016 at 05​:37​:04AM -0800, James E Keenan via RT wrote​:

On Wed, 28 Dec 2016 06​:00​:21 GMT, tauner@​technikum-wien.at wrote​:

h2xs -x booltest.h
So this might be a bug in C​::Scan (which I have installed via cpanm
from HVDS/C-Scan-0.74)?

What happens if you do not use the '-x' option and thereby avoid
C​::Scan?

(When I did that, 'make' completed -- but since I've rarely attempted
to write XS I don't know whether that's meaningful or not.)

Thank you very much.

When foo,h contains this​:

#include <stdbool.h>
void h2xs(bool b);

then h2xs -x foo.h, via C​::Scan, is generating an XS file that looks
like​:

void
h2xs(arg0)

I'll try to take a look later this week at the C​::Scan side, to see if this is fixable; I don't have stdbool.h here, but I'm guessing that something like <http​://clang.llvm.org/doxygen/stdbool_8h_source.html> should be close enough.

Hugo

From @iabyn

On Wed, Dec 28, 2016 at 11​:56​:11PM -0800, Hugo van der Sanden via RT wrote​:

On Wed, 28 Dec 2016 07​:13​:36 -0800, davem wrote​:

On Wed, Dec 28, 2016 at 05​:37​:04AM -0800, James E Keenan via RT wrote​:

On Wed, 28 Dec 2016 06​:00​:21 GMT, tauner@​technikum-wien.at wrote​:

h2xs -x booltest.h
So this might be a bug in C​::Scan (which I have installed via cpanm
from HVDS/C-Scan-0.74)?

What happens if you do not use the '-x' option and thereby avoid
C​::Scan?

(When I did that, 'make' completed -- but since I've rarely attempted
to write XS I don't know whether that's meaningful or not.)

Thank you very much.

When foo,h contains this​:

#include <stdbool.h>
void h2xs(bool b);

then h2xs -x foo.h, via C​::Scan, is generating an XS file that looks
like​:

void
h2xs(arg0)

I'll try to take a look later this week at the C​::Scan side, to see if this is fixable; I don't have stdbool.h here, but I'm guessing that something like <http​://clang.llvm.org/doxygen/stdbool_8h_source.html> should be close enough.

It seems very sensitive. I tried as small a change as replacing this line​:

  #include <stdbool.h>

with this this line

  #include "/usr/lib/gcc/x86_64-redhat-linux/5.3.1/include/stdbool.h"

(which from stracing the h2xs command appears to be the file it reads)
and the problem magically goes away.

That file is attached.

--
Lear​: Dost thou call me fool, boy?
Fool​: All thy other titles thou hast given away; that thou wast born with.

From @iabyn

/* Copyright (C) 1998-2015 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http​://www.gnu.org/licenses/>. */

/*
* ISO C Standard​: 7.16 Boolean type and values <stdbool.h>
*/

#ifndef _STDBOOL_H
#define _STDBOOL_H

#ifndef __cplusplus

#define bool _Bool
#define true 1
#define false 0

#else /* __cplusplus */

/* Supporting _Bool in C++ is a GCC extension. */
#define _Bool bool

#if __cplusplus < 201103L
/* Defining these macros in C++98 is a GCC extension. */
#define bool bool
#define false false
#define true true
#endif

#endif /* __cplusplus */

/* Signal that all the definitions are present. */
#define __bool_true_false_are_defined 1

#endif /* stdbool.h */

From @hvds

On Wed, 28 Dec 2016 07​:13​:36 -0800, davem wrote​:

When foo,h contains this​:

#include <stdbool.h>
void h2xs(bool b);

then h2xs -x foo.h, via C​::Scan, is generating an XS file that looks
like​:

void
h2xs(arg0)

which is being converted into the C code

XS_EUPXS(XS_Foo_h2xs); /* prototype to pass -Wmissing-prototypes */
XS_EUPXS(XS_Foo_h2xs)
{
dVAR; dXSARGS;
if (items != 1)
croak_xs_usage(cv, "arg0");
{

h2xs(arg0);
}
XSRETURN_EMPTY;
}

The issues seem to be that

1) h2xs and/or C​::Scan isn't including the variable type for arg0 in
the
generated XS; I assume that it should have output​:

void
h2xs(bool arg0)

I'm seeing it output this (which I believe is correct)​:
void
h2xs(b)
  _Bool b

2) that ExtUtils/xsubpp isn't seeing that as an error and is instead
converting it onto invalid C code, by not including the line​:

bool arg0 = (bool)SvTRUE(ST(0))

For me, xsubpp is giving this​:

  _Bool b;

  if (SvROK(ST(0)) && sv_derived_from(ST(0), "_Bool")) {
  IV tmp = SvIV((SV*)SvRV(ST(0)));
  b = INT2PTR(_Bool,tmp);
  }
  else [...]

I haven't been able to reproduce the case of a missing '_Bool b' declaration in Foo.xs, so I'm stuck on this for now.

Hugo

From @Leont

On Sat, Dec 31, 2016 at 3​:04 PM, Hugo van der Sanden via RT <
perlbug-followup@​perl.org> wrote​:

On Wed, 28 Dec 2016 07​:13​:36 -0800, davem wrote​:

When foo,h contains this​:

#include <stdbool.h>
void h2xs(bool b);

then h2xs -x foo.h, via C​::Scan, is generating an XS file that looks
like​:

void
h2xs(arg0)

which is being converted into the C code

XS_EUPXS(XS_Foo_h2xs); /* prototype to pass -Wmissing-prototypes */
XS_EUPXS(XS_Foo_h2xs)
{
dVAR; dXSARGS;
if (items != 1)
croak_xs_usage(cv, "arg0");
{

h2xs(arg0);
}
XSRETURN_EMPTY;
}

The issues seem to be that

1) h2xs and/or C​::Scan isn't including the variable type for arg0 in
the
generated XS; I assume that it should have output​:

void
h2xs(bool arg0)

I'm seeing it output this (which I believe is correct)​:
void
h2xs(b)
_Bool b

2) that ExtUtils/xsubpp isn't seeing that as an error and is instead
converting it onto invalid C code, by not including the line​:

bool arg0 = (bool)SvTRUE(ST(0))

For me, xsubpp is giving this​:

\_Bool   b;

if \(SvROK\(ST\(0\)\) && sv\_derived\_from\(ST\(0\)\, "\_Bool"\)\) \{
    IV tmp = SvIV\(\(SV\*\)SvRV\(ST\(0\)\)\);
    b = INT2PTR\(\_Bool\,tmp\);
\}
else \[\.\.\.\]

I haven't been able to reproduce the case of a missing '_Bool b'
declaration in Foo.xs, so I'm stuck on this for now.

Hugo

It seems to assume _Bool is some kind of object type, for some reason,
hence my previous suggestion for an explicit typemap.

Leon