X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Finclude_next.m4;h=b6e4d3ae7a92c2e1a7c83b5325a31fadf25f8ff7;hb=8eaac7a51d093dbcecc0c2b42a5762a882b4517b;hp=dfd5ec574ae04ce6bfccbe21f89f6ac26b3fc779;hpb=b6a9d33ee89de0a0f7bf482449339e97cbbbdaef;p=gnulib.git

diff --git a/m4/include_next.m4 b/m4/include_next.m4
index dfd5ec574..b6e4d3ae7 100644
--- a/m4/include_next.m4
+++ b/m4/include_next.m4
@@ -1,31 +1,71 @@
-# include_next.m4 serial 2
-dnl Copyright (C) 2006, 2007 Free Software Foundation, Inc.
+# include_next.m4 serial 8
+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,
 dnl with or without modifications, as long as this notice is preserved.
 
 dnl From Paul Eggert and Derek Price.
 
+dnl Sets INCLUDE_NEXT and PRAGMA_SYSTEM_HEADER.
+dnl
+dnl INCLUDE_NEXT expands to 'include_next' if the compiler supports it, or to
+dnl '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
+dnl through the include search path specified with '-isystem' options (as
+dnl opposed to the search path specified with '-I' options). Namely, gcc
+dnl does not warn about some things, and on some systems (Solaris and Interix)
+dnl __STDC__ evaluates to 0 instead of to 1. The latter is an undesired side
+dnl effect; we are therefore careful to use 'defined __STDC__' or '1' instead
+dnl of plain '__STDC__'.
+
 AC_DEFUN([gl_INCLUDE_NEXT],
 [
   AC_LANG_PREPROC_REQUIRE()
   AC_CACHE_CHECK([whether the preprocessor supports include_next],
     [gl_cv_have_include_next],
-    [AC_PREPROC_IFELSE([#include_next <stddef.h>],
+    [rm -rf conftestd1 conftestd2
+     mkdir conftestd1 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
+#define DEFINED_IN_CONFTESTD1
+#include <stdio.h>
+#include_next <conftest.h>
+#ifdef DEFINED_IN_CONFTESTD2
+int foo;
+#else
+#error "include_next doesn't work"
+#endif
+EOF
+     cat <<EOF > conftestd2/conftest.h
+#ifndef DEFINED_IN_CONFTESTD1
+#error "include_next test doesn't work"
+#endif
+#define DEFINED_IN_CONFTESTD2
+EOF
+     save_CPPFLAGS="$CPPFLAGS"
+     CPPFLAGS="$CPPFLAGS -Iconftestd1 -Iconftestd2"
+     AC_COMPILE_IFELSE([#include <conftest.h>],
        [gl_cv_have_include_next=yes],
-       [gl_cv_have_include_next=no])])
+       [gl_cv_have_include_next=no])
+     CPPFLAGS="$save_CPPFLAGS"
+     rm -rf conftestd1 conftestd2
+    ])
+  PRAGMA_SYSTEM_HEADER=
   if test $gl_cv_have_include_next = yes; then
-
-    dnl FIXME: Remove HAVE_INCLUDE_NEXT and update everything that uses it
-    dnl to use @INCLUDE_NEXT@ instead.
-    AC_DEFINE([HAVE_INCLUDE_NEXT], 1,
-	      [Define if your compiler supports the #include_next directive.])
-
     INCLUDE_NEXT=include_next
+    if test -n "$GCC"; then
+      PRAGMA_SYSTEM_HEADER='#pragma GCC system_header'
+    fi
   else
     INCLUDE_NEXT=include
   fi
   AC_SUBST([INCLUDE_NEXT])
+  AC_SUBST([PRAGMA_SYSTEM_HEADER])
 ])
 
 # gl_CHECK_NEXT_HEADERS(HEADER1 HEADER2 ...)
@@ -41,20 +81,26 @@ AC_DEFUN([gl_INCLUDE_NEXT],
 # The three "///" are to pacify Sun C 5.8, which otherwise would say
 # "warning: #include of /usr/include/... may be non-portable".
 # Use `""', not `<>', so that the /// cannot be confused with a C99 comment.
+# Note: This macro assumes that the header file is not empty after
+# preprocessing, i.e. it does not only define preprocessor macros but also
+# provides some type/enum definitions or function/variable declarations.
 AC_DEFUN([gl_CHECK_NEXT_HEADERS],
 [
   AC_REQUIRE([gl_INCLUDE_NEXT])
   AC_CHECK_HEADERS_ONCE([$1])
 
-  AC_FOREACH([gl_HEADER_NAME], [$1],
+  m4_foreach_w([gl_HEADER_NAME], [$1],
     [AS_VAR_PUSHDEF([gl_next_header],
 		    [gl_cv_next_]m4_quote(m4_defn([gl_HEADER_NAME])))
-     AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
-     if test $gl_cv_have_include_next = no; then
+     if test $gl_cv_have_include_next = yes; then
+       AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
+     else
        AC_CACHE_CHECK(
 	 [absolute name of <]m4_quote(m4_defn([gl_HEADER_NAME]))[>],
 	 m4_quote(m4_defn([gl_next_header])),
-	 [if test AS_VAR_GET([ac_cv_header_]m4_quote(m4_defn([gl_HEADER_NAME]))) = yes; then
+	 [AS_VAR_PUSHDEF([gl_header_exists],
+			 [ac_cv_header_]m4_quote(m4_defn([gl_HEADER_NAME])))
+	  if test AS_VAR_GET(gl_header_exists) = yes; then
 	    AC_LANG_CONFTEST(
 	      [AC_LANG_SOURCE(
 		 [[#include <]]m4_dquote(m4_defn([gl_HEADER_NAME]))[[>]]
@@ -70,7 +116,10 @@ AC_DEFUN([gl_CHECK_NEXT_HEADERS],
 		 p
 		 q
 	       }'`'"'])
-	  fi])
+	  else
+	    AS_VAR_SET([gl_next_header], ['<'gl_HEADER_NAME'>'])
+	  fi
+	  AS_VAR_POPDEF([gl_header_exists])])
      fi
      AC_SUBST(
        AS_TR_CPP([NEXT_]m4_quote(m4_defn([gl_HEADER_NAME]))),