From 21c74b6ea41d21ef96813b34bfa55c51a82d6c99 Mon Sep 17 00:00:00 2001
From: Xi Ruoyao <xry111@xry111.site>
Date: Tue, 28 Mar 2023 01:48:02 +0800
Subject: fixincludes: Declare memmem if it's not declared in system headers
 [PR109293]

memmem is not POSIX so the system may lack it.  Then libiberty will
provide an implementation, but it's a "supplemental function" and not
declared in libiberty.h.  We need to declare the prototype to use it
then.

See libiberty doc at
https://gcc.gnu.org/onlinedocs/libiberty/Supplemental-Functions.html.

Tested by bootstrapping GCC in the following container environments on
x86_64-linux-gnu:

1. "Vanilla" system with memmem in Glibc.
2. memmem removed from string.h.
3. memmem removed from both string.h and libc.so.

For 3, also verified that memmem from libiberty is linked into fixincl
executable.

Ok for trunk?

fixincludes/ChangeLog:

	PR other/109293
	* configure.ac (AC_CHECK_DECLS): Add memmem.
	* configure: Regenerate.
	* config.h.in: Regenerate.
	* system.h (memmem): Declare if HAVE_DECL_MEMMEM is zero.
---
 fixincludes/config.h.in  |  4 ++++
 fixincludes/configure    | 10 ++++++++++
 fixincludes/configure.ac |  2 +-
 fixincludes/system.h     |  4 ++++
 4 files changed, 19 insertions(+), 1 deletion(-)

(limited to 'fixincludes')

diff --git a/fixincludes/config.h.in b/fixincludes/config.h.in
index 69a67f5..0fd21b7 100644
--- a/fixincludes/config.h.in
+++ b/fixincludes/config.h.in
@@ -78,6 +78,10 @@
    don't. */
 #undef HAVE_DECL_GETC_UNLOCKED
 
+/* Define to 1 if you have the declaration of `memmem', and to 0 if you don't.
+   */
+#undef HAVE_DECL_MEMMEM
+
 /* Define to 1 if you have the declaration of `putchar_unlocked', and to 0 if
    you don't. */
 #undef HAVE_DECL_PUTCHAR_UNLOCKED
diff --git a/fixincludes/configure b/fixincludes/configure
index b3bca66..bdcc41f 100755
--- a/fixincludes/configure
+++ b/fixincludes/configure
@@ -5043,6 +5043,16 @@ fi
 cat >>confdefs.h <<_ACEOF
 #define HAVE_DECL_VASPRINTF $ac_have_decl
 _ACEOF
+ac_fn_c_check_decl "$LINENO" "memmem" "ac_cv_have_decl_memmem" "$ac_includes_default"
+if test "x$ac_cv_have_decl_memmem" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_MEMMEM $ac_have_decl
+_ACEOF
 
 ac_fn_c_check_decl "$LINENO" "clearerr_unlocked" "ac_cv_have_decl_clearerr_unlocked" "$ac_includes_default"
 if test "x$ac_cv_have_decl_clearerr_unlocked" = xyes; then :
diff --git a/fixincludes/configure.ac b/fixincludes/configure.ac
index 14813b9..ef2227e 100644
--- a/fixincludes/configure.ac
+++ b/fixincludes/configure.ac
@@ -88,7 +88,7 @@ define(fixincludes_UNLOCKED_FUNCS, clearerr_unlocked feof_unlocked dnl
   fread_unlocked fwrite_unlocked getchar_unlocked getc_unlocked dnl
   putchar_unlocked putc_unlocked)
 AC_CHECK_FUNCS(fixincludes_UNLOCKED_FUNCS)
-AC_CHECK_DECLS([abort, asprintf, basename(char *), errno, vasprintf])
+AC_CHECK_DECLS([abort, asprintf, basename(char *), errno, vasprintf, memmem])
 AC_CHECK_DECLS(m4_split(m4_normalize(fixincludes_UNLOCKED_FUNCS)))
 
 # Checks for typedefs, structures, and compiler characteristics.
diff --git a/fixincludes/system.h b/fixincludes/system.h
index dca5d57..687fb2e 100644
--- a/fixincludes/system.h
+++ b/fixincludes/system.h
@@ -209,6 +209,10 @@ extern int errno;
 extern void abort (void);
 #endif
 
+#if defined (HAVE_DECL_MEMMEM) && !HAVE_DECL_MEMMEM
+extern void *memmem (const void *, size_t, const void *, size_t);
+#endif
+
 #if HAVE_SYS_STAT_H
 # include <sys/stat.h>
 #endif
-- 
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