#578923 [autoconf] Warning if testing for declaration with namespace (std::setlocale)

Package:
autoconf
Source:
autoconf
Submitter:
Jens Seidel
Date:
2010-08-02 21:33:04 UTC
Severity:
minor
#578923#5
Date:
2010-04-23 15:30:55 UTC
From:
To:
The following configure.ac fragment

AC_LANG_PUSH(C++)
AC_CHECK_DECL(std::setlocale, [AC_DEFINE([HAVE_SETLOCALE], [], [Define if
setlocale is available in clocale])], , [#include <clocale>])

results in the warning
conftest.cpp:37:12: warning: extra tokens at end of #ifndef directive
in config.log.

The corresponding code is:

#include <clocale>

int
main ()
{
#ifndef std::setlocale
  (void) std::setlocale;
#endif

  ;
  return 0;
}

The problem is "#ifndef std::setlocale" where ":" is no proper macro
character. In this case the ifndef can be ommitted.

Jens
#578923#10
Date:
2010-04-25 11:34:15 UTC
From:
To:
tags +upstream
thanks

Hello Jens,

this is clearly an upstream bug.  Adding bug-autoconf.

* Jens Seidel wrote on Fri, Apr 23, 2010 at 05:30:55PM CEST:

Yep.  This is another problem with the AC_CHECK_DECL* macros and C++
sources.  There is a pending patch for another issue in this area,
http://thread.gmane.org/gmane.comp.gcc.patches/201265/focus=12673
but it does not address the above.

It would probably be sufficient to just not use the #ifndef if the name
contained characters not suitable for a CPP macro.

Cheers, and thanks for the bug report,
Ralf
#578923#17
Date:
2010-08-02 20:47:37 UTC
From:
To:
I'm looking over old bug reports before uploading 2.67.

Using the following configure.ac:

    AC_INIT
    AC_PREREQ(2.59)
    AC_LANG_PUSH(C++)
    AC_CHECK_DECL(std::setlocale, [AC_DEFINE([HAVE_SETLOCALE], [], [Define if
    setlocale is available in clocale])], , [#include <clocale>])
    AC_OUTPUT

I confirmed that this bug is still present.  Notably, the
following appears in config.log:

    conftest.cpp:14:12: warning: extra tokens at end of #ifndef directive

and by editing the configure script directly I found that indeed,
the generated program was still this:

    /* confdefs.h */
    #define PACKAGE_NAME ""
    #define PACKAGE_TARNAME ""
    #define PACKAGE_VERSION ""
    #define PACKAGE_STRING ""
    #define PACKAGE_BUGREPORT ""
    #define PACKAGE_URL ""
    /* end confdefs.h.  */
    #include <clocale>

    int
    main ()
    {
    #ifndef std::setlocale
    #ifdef __cplusplus
      (void) std::setlocale;
    #else
      (void) std::setlocale;
    #endif
    #endif

      ;
      return 0;
    }