Hello Albert,
> (AIX 6.1)
> $ cat conftest.c
> #include "///usr/vac/include/math.h"
> int a = HUGE_VAL;
> $ xlc -D_ALL_SOURCE -E conftest.c | tail
> #line 2 "conftest.c"
> int a = HUGE_VAL;
> ...
> /usr/vac/include/math.h includes /usr/include/math.h with:
> #include_next <math.h>
>
> I have no idea why:
> #include <math.h>
> behaves differently than:
> #include "///usr/vac/include/math.h"
> You'd figure with the #include_next <math.h> in /usr/vac/include/math.h
> the behavior would be the same. However, the #include_next <math.h> in
> /usr/vac/include/math.h is turned into a no-op.
Thanks for this problem summary. Since #include <math.h> works, it's not
a problem with the inclusion guards (the "#ifdef _H_MATH" or similar), but
- as you say - a problem with #include_next itself.
What's the result of
$ grep include_next /usr/vac/include/*.h /usr/vac/include/*/*.h
?
Probably the only solution is to use #include_next only in gnulib's math.in.h
but not in the other header files that are overridden by gnulib. I'm applying
this; please let us know whether it works.
Bruno
2008-11-20 Bruno Haible <[EMAIL PROTECTED]>
Attempt to work around an AIX 5.3, 6.1 compiler bug with include_next.
* lib/math.in.h: Use INCLUDE_NEXT_AS_FIRST_DIRECTIVE instead of
INCLUDE_NEXT.
* m4/include_next.m4 (gl_INCLUDE_NEXT): Set also
INCLUDE_NEXT_AS_FIRST_DIRECTIVE.
* modules/math (Makefile.am): Substitute
INCLUDE_NEXT_AS_FIRST_DIRECTIVE instead of INCLUDE_NEXT.
Reported by Albert Chin <[EMAIL PROTECTED]>.
--- lib/math.in.h.orig 2008-11-20 23:29:33.000000000 +0100
+++ lib/math.in.h 2008-11-20 23:26:08.000000000 +0100
@@ -22,7 +22,7 @@
#endif
/* The include_next requires a split double-inclusion guard. */
[EMAIL PROTECTED]@ @NEXT_MATH_H@
[EMAIL PROTECTED]@ @NEXT_MATH_H@
#ifndef _GL_MATH_H
#define _GL_MATH_H
--- m4/include_next.m4.orig 2008-11-20 23:40:29.000000000 +0100
+++ m4/include_next.m4 2008-11-20 23:36:44.000000000 +0100
@@ -1,4 +1,4 @@
-# include_next.m4 serial 9
+# include_next.m4 serial 10
dnl Copyright (C) 2006-2008 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -11,6 +11,10 @@
dnl INCLUDE_NEXT expands to 'include_next' if the compiler supports it, or to
dnl 'include' otherwise.
dnl
+dnl INCLUDE_NEXT_AS_FIRST_DIRECTIVE expands to 'include_next' if the compiler
+dnl supports it in the special case that it is the first include directive in
+dnl the given file, or to 'include' otherwise.
+dnl
dnl PRAGMA_SYSTEM_HEADER can be used in files that contain #include_next,
dnl so as to avoid GCC warnings when the gcc option -pedantic is used.
dnl '#pragma GCC system_header' has the same effect as if the file was found
@@ -26,12 +30,26 @@
AC_LANG_PREPROC_REQUIRE()
AC_CACHE_CHECK([whether the preprocessor supports include_next],
[gl_cv_have_include_next],
- [rm -rf conftestd1 conftestd2
- mkdir conftestd1 conftestd2
+ [rm -rf conftestd1a conftestd1b conftestd2
+ mkdir conftestd1a conftestd1b conftestd2
dnl The include of <stdio.h> is because IBM C 9.0 on AIX 6.1 supports
dnl include_next when used as first preprocessor directive in a file,
- dnl but not when preceded by another include directive.
- cat <<EOF > conftestd1/conftest.h
+ dnl but not when preceded by another include directive. Additionally,
+ dnl with this same compiler, include_next is a no-op when used in a
+ dnl header file that was included by specifying its absolute file name.
+ dnl Despite these two bugs, include_next is used in the compiler's
+ dnl <math.h>. By virtue of the second bug, we need to use include_next
+ dnl as well in this case.
+ cat <<EOF > conftestd1a/conftest.h
+#define DEFINED_IN_CONFTESTD1
+#include_next <conftest.h>
+#ifdef DEFINED_IN_CONFTESTD2
+int foo;
+#else
+#error "include_next doesn't work"
+#endif
+EOF
+ cat <<EOF > conftestd1b/conftest.h
#define DEFINED_IN_CONFTESTD1
#include <stdio.h>
#include_next <conftest.h>
@@ -47,24 +65,36 @@
#endif
#define DEFINED_IN_CONFTESTD2
EOF
- save_CPPFLAGS="$CPPFLAGS"
- CPPFLAGS="$CPPFLAGS -Iconftestd1 -Iconftestd2"
+ gl_save_CPPFLAGS="$CPPFLAGS"
+ CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1b -Iconftestd2"
AC_COMPILE_IFELSE([#include <conftest.h>],
[gl_cv_have_include_next=yes],
- [gl_cv_have_include_next=no])
- CPPFLAGS="$save_CPPFLAGS"
- rm -rf conftestd1 conftestd2
+ [CPPFLAGS="$gl_save_CPPFLAGS -Iconftestd1a -Iconftestd2"
+ AC_COMPILE_IFELSE([#include <conftest.h>],
+ [gl_cv_have_include_next=buggy],
+ [gl_cv_have_include_next=no])
+ ])
+ CPPFLAGS="$gl_save_CPPFLAGS"
+ rm -rf conftestd1a conftestd1b conftestd2
])
PRAGMA_SYSTEM_HEADER=
if test $gl_cv_have_include_next = yes; then
INCLUDE_NEXT=include_next
+ INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next
if test -n "$GCC"; then
PRAGMA_SYSTEM_HEADER='#pragma GCC system_header'
fi
else
- INCLUDE_NEXT=include
+ if test $gl_cv_have_include_next = buggy; then
+ INCLUDE_NEXT=include
+ INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include_next
+ else
+ INCLUDE_NEXT=include
+ INCLUDE_NEXT_AS_FIRST_DIRECTIVE=include
+ fi
fi
AC_SUBST([INCLUDE_NEXT])
+ AC_SUBST([INCLUDE_NEXT_AS_FIRST_DIRECTIVE])
AC_SUBST([PRAGMA_SYSTEM_HEADER])
])
--- modules/math.orig 2008-11-20 23:29:33.000000000 +0100
+++ modules/math 2008-11-20 23:26:18.000000000 +0100
@@ -20,7 +20,7 @@
math.h: math.in.h
rm -f [EMAIL PROTECTED] $@
{ echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */' && \
- sed -e 's|@''INCLUDE_NEXT''@|$(INCLUDE_NEXT)|g' \
+ sed -e
's|@''INCLUDE_NEXT_AS_FIRST_DIRECTIVE''@|$(INCLUDE_NEXT_AS_FIRST_DIRECTIVE)|g' \
-e 's|@''PRAGMA_SYSTEM_HEADER''@|@PRAGMA_SYSTEM_HEADER@|g' \
-e 's|@''NEXT_MATH_H''@|$(NEXT_MATH_H)|g' \
-e 's|@''GNULIB_CEILF''@|$(GNULIB_CEILF)|g' \
