Re: multiple definitions of __printf__

[Bruno Haible]

Ben Pfaff wrote:
> This fixes the build in the case where both libintl and PSPP's
> Gnulib define __printf__.  But it broke the build in the
> previously working case where libintl did not define __printf__
> but PSPP's Gnulib did and no longer does.  This is the case on,
> for example, FreeBSD 7.3 and, according to reports on pspp-dev,
> OpenSUSE as well.
> 
> Is the best solution to check whether libintl defines __printf__
> and, if so, avoid defining it in Gnulib?

This would have been better than what I committed in March, yes.

But it would not fix another problem: On a platform when libintl
defines __printf__, this replacement is not necessarily POSIX compliant.
(It only adds the support for argument reordering, which is essential
for i18n.) If then the user requires gnulib module 'printf-posix',
he would still not be getting a POSIX compliant printf() function.

This should fix both problems:


2010-05-16  Bruno Haible  <address@hidden>

        Fix collision between gnulib's and libintl's printf replacements.
        * lib/stdio.in.h (_GL_STDIO_STRINGIZE,
        _GL_STDIO_MACROEXPAND_AND_STRINGIZE): New macros.
        (printf): When using GNU C, map the __printf__ function to rpl_printf
        via __asm__. When not using GNU C, define rpl_printf instead of
        __printf__.
        * lib/printf.c: Ignore DEPENDS_ON_LIBINTL. Undoes the 2010-03-25
        commit.
        * lib/stdio-write.c: Ignore DEPENDS_ON_LIBINTL. Undoes the 2009-08-10
        commit.
        * m4/asm-underscore.m4: New file.
        * m4/stdio_h.m4 (gl_STDIO_H): Require gl_ASM_SYMBOL_PREFIX.
        * modules/stdio (Files): Add m4/asm-underscore.m4.
        (Makefile.am): Substitute ASM_SYMBOL_PREFIX.
        Reported by Ben Pfaff.

--- lib/printf.c.orig   Sun May 16 14:08:11 2010
+++ lib/printf.c        Sun May 16 12:11:07 2010
@@ -23,8 +23,6 @@
 
 #include <stdarg.h>
 
-#if !DEPENDS_ON_LIBINTL /* avoid collision with intl/printf.c */
-
 /* Print formatted output to standard output.
    Return string length of formatted string.  On error, return a negative
    value.  */
@@ -40,5 +38,3 @@
 
   return retval;
 }
-
-#endif
--- lib/stdio-write.c.orig      Sun May 16 14:08:12 2010
+++ lib/stdio-write.c   Sun May 16 12:11:22 2010
@@ -63,7 +63,6 @@
     }
 
 #  if !REPLACE_PRINTF_POSIX /* avoid collision with printf.c */
-#   if !DEPENDS_ON_LIBINTL /* avoid collision with intl/printf.c */
 int
 printf (const char *format, ...)
 {
@@ -76,7 +75,6 @@
 
   return retval;
 }
-#   endif
 #  endif
 
 #  if !REPLACE_FPRINTF_POSIX /* avoid collision with fprintf.c */
--- lib/stdio.in.h.orig Sun May 16 14:08:12 2010
+++ lib/stdio.in.h      Sun May 16 13:01:19 2010
@@ -63,6 +63,10 @@
 
 /* The definition of _GL_WARN_ON_USE is copied here.  */
 
+/* Macros for stringification.  */
+#define _GL_STDIO_STRINGIZE(token) #token
+#define _GL_STDIO_MACROEXPAND_AND_STRINGIZE(token) _GL_STDIO_STRINGIZE(token)
+
 
 #if @GNULIB_DPRINTF@
 # if @REPLACE_DPRINTF@
@@ -640,16 +644,26 @@
 #if @GNULIB_PRINTF_POSIX@ || @GNULIB_PRINTF@
 # if (@GNULIB_PRINTF_POSIX@ && @REPLACE_PRINTF@) \
      || (@GNULIB_PRINTF@ && @REPLACE_STDIO_WRITE_FUNCS@ && 
@GNULIB_STDIO_H_SIGPIPE@)
-#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#  if defined __GNUC__
+#   if !(defined __cplusplus && defined GNULIB_NAMESPACE)
 /* Don't break __attribute__((format(printf,M,N))).  */
-#   define printf __printf__
-#  endif
-#  define GNULIB_overrides_printf 1
+#    define printf __printf__
+#   endif
 _GL_FUNCDECL_RPL_1 (__printf__, int,
                     (const char *format, ...)
+                    __asm__ (@ASM_SYMBOL_PREFIX@
+                             _GL_STDIO_MACROEXPAND_AND_STRINGIZE(rpl_printf))
                     __attribute__ ((__format__ (__printf__, 1, 2)))
                     _GL_ARG_NONNULL ((1)));
 _GL_CXXALIAS_RPL_1 (printf, __printf__, int, (const char *format, ...));
+#  else
+_GL_FUNCDECL_RPL (printf, int,
+                  (const char *format, ...)
+                  __attribute__ ((__format__ (__printf__, 1, 2)))
+                  _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (printf, printf, int, (const char *format, ...));
+#  endif
+#  define GNULIB_overrides_printf 1
 # else
 _GL_CXXALIAS_SYS (printf, int, (const char *format, ...));
 # endif
--- m4/stdio_h.m4.orig  Sun May 16 14:08:12 2010
+++ m4/stdio_h.m4       Sun May 16 12:57:02 2010
@@ -1,4 +1,4 @@
-# stdio_h.m4 serial 30
+# stdio_h.m4 serial 31
 dnl Copyright (C) 2007-2010 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -8,6 +8,7 @@
 [
   AC_REQUIRE([gl_STDIO_H_DEFAULTS])
   AC_REQUIRE([AC_C_INLINE])
+  AC_REQUIRE([gl_ASM_SYMBOL_PREFIX])
   gl_CHECK_NEXT_HEADERS([stdio.h])
   dnl No need to create extra modules for these functions. Everyone who uses
   dnl <stdio.h> likely needs them.
--- modules/stdio.orig  Sun May 16 14:08:12 2010
+++ modules/stdio       Sun May 16 12:56:21 2010
@@ -5,6 +5,7 @@
 lib/stdio.in.h
 lib/stdio-write.c
 m4/stdio_h.m4
+m4/asm-underscore.m4
 
 Depends-on:
 include_next
@@ -112,6 +113,7 @@
              -e 's|@''REPLACE_VPRINTF''@|$(REPLACE_VPRINTF)|g' \
              -e 's|@''REPLACE_VSNPRINTF''@|$(REPLACE_VSNPRINTF)|g' \
              -e 's|@''REPLACE_VSPRINTF''@|$(REPLACE_VSPRINTF)|g' \
+             -e 's|@''ASM_SYMBOL_PREFIX''@|$(ASM_SYMBOL_PREFIX)|g' \
              -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
              -e '/definition of _GL_ARG_NONNULL/r $(ARG_NONNULL_H)' \
              -e '/definition of _GL_WARN_ON_USE/r $(WARN_ON_USE_H)'; \
============================ m4/asm-underscore.m4 ============================
# asm-underscore.m4 serial 1
dnl Copyright (C) 2010 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

dnl From Bruno Haible. Based on as-underscore.m4 in GNU clisp.

# gl_ASM_SYMBOL_PREFIX
# Tests for the prefix of C symbols at the assembly language level and the
# linker level. This prefix is either an underscore or empty. Defines the
# C macro USER_LABEL_PREFIX to this prefix, and sets ASM_SYMBOL_PREFIX to
# a stringified variant of this prefix.

AC_DEFUN([gl_ASM_SYMBOL_PREFIX],
[
  dnl We don't use GCC's __USER_LABEL_PREFIX__ here, because
  dnl 1. It works only for GCC.
  dnl 2. It is incorrectly defined on some platforms, in some GCC versions.
  AC_CACHE_CHECK(
    [whether C symbols are prefixed with underscore at the linker level],
    [gl_cv_prog_as_underscore],
    [cat > conftest.c <<EOF
#ifdef __cplusplus
extern "C" int foo (void);
#endif
int foo(void) { return 0; }
EOF
     # Look for the assembly language name in the .s file.
     AC_TRY_COMMAND(${CC-cc} $CFLAGS $CPPFLAGS -S conftest.c) >/dev/null 2>&1
     if grep _foo conftest.s >/dev/null ; then
       gl_cv_prog_as_underscore=yes
     else
       gl_cv_prog_as_underscore=no
     fi
     rm -f conftest*
    ])
  if test $gl_cv_prog_as_underscore = yes; then
    USER_LABEL_PREFIX=_
  else
    USER_LABEL_PREFIX=
  fi
  AC_DEFINE_UNQUOTED([USER_LABEL_PREFIX], [$USER_LABEL_PREFIX],
    [Define to the prefix of C symbols at the assembler and linker level,
     either an underscore or empty.])
  ASM_SYMBOL_PREFIX='"'${USER_LABEL_PREFIX}'"'
  AC_SUBST([ASM_SYMBOL_PREFIX])
])