memchr: Remove support for some very old platforms.

* m4/memchr-obsolete.m4: Remove file.
* modules/memchr-obsolete: Remove file.
* m4/memchr.m4 (gl_FUNC_MEMCHR): Assume module 'memchr-obsolete' is
absent. Don't define HAVE_MEMCHR.
* lib/string.in.h (memchr): Assume HAVE_MEMCHR is 1.
* modules/memchr (Depends-on): Remove memchr-obsolete.
(configure.ac): Assume HAVE_MEMCHR is 1.
* m4/string_h.m4 (gl_HEADER_STRING_H_DEFAULTS): Don't initialize
HAVE_MEMCHR.
* modules/string (Makefile.am): Don't substitute HAVE_MEMCHR.
* doc/posix-functions/memchr.texi: Don't mention module
'memchr-obsolete'.
* m4/strcasestr.m4 (gl_FUNC_STRCASESTR_SIMPLE): Assume HAVE_MEMCHR is 1.
* m4/strstr.m4 (gl_FUNC_STRSTR_SIMPLE): Assume HAVE_MEMCHR is 1.
* modules/strnlen (Depends-on): Remove memchr-obsolete.

5 files changed, 33 insertions, 55 deletions

diff --git a/m4/memchr-obsolete.m4 b/m4/memchr-obsolete.m4
deleted file mode 100644
index 7305a77e46..0000000000
--- a/m4/memchr-obsolete.m4
+++ /dev/null
@@ -1,11 +0,0 @@
-# memchr-obsolete.m4 serial 1
-dnl Copyright (C) 2011-2020 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.
-
-AC_DEFUN([gl_FUNC_MEMCHR_OBSOLETE],
-[
-  dnl The real code is in memchr.m4.
-  :
-])
diff --git a/m4/memchr.m4 b/m4/memchr.m4
index 91eec88e09..81e8f985df 100644
--- a/m4/memchr.m4
+++ b/m4/memchr.m4
@@ -1,4 +1,4 @@
-# memchr.m4 serial 15
+# memchr.m4 serial 16
 dnl Copyright (C) 2002-2004, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -14,26 +14,17 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
   AC_CHECK_FUNCS_ONCE([mprotect])
 
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
-  m4_ifdef([gl_FUNC_MEMCHR_OBSOLETE], [
-    dnl These days, we assume memchr is present.  But if support for old
-    dnl platforms is desired:
-    AC_CHECK_FUNCS_ONCE([memchr])
-    if test $ac_cv_func_memchr = no; then
-      HAVE_MEMCHR=0
-    fi
-  ])
-  if test $HAVE_MEMCHR = 1; then
-    # Detect platform-specific bugs in some versions of glibc:
-    # memchr should not dereference anything with length 0
-    #   https://bugzilla.redhat.com/show_bug.cgi?id=499689
-    # memchr should not dereference overestimated length after a match
-    #   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737
-    #   https://sourceware.org/bugzilla/show_bug.cgi?id=10162
-    # memchr should cast the second argument to 'unsigned char'.
-    #   This bug exists in Android 4.3.
-    # Assume that memchr works on platforms that lack mprotect.
-    AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works],
-      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+  # Detect platform-specific bugs in some versions of glibc:
+  # memchr should not dereference anything with length 0
+  #   https://bugzilla.redhat.com/show_bug.cgi?id=499689
+  # memchr should not dereference overestimated length after a match
+  #   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737
+  #   https://sourceware.org/bugzilla/show_bug.cgi?id=10162
+  # memchr should cast the second argument to 'unsigned char'.
+  #   This bug exists in Android 4.3.
+  # Assume that memchr works on platforms that lack mprotect.
+  AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works],
+    [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
 #include <string.h>
 #if HAVE_SYS_MMAN_H
 # include <fcntl.h>
@@ -87,23 +78,22 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
   }
   return result;
 ]])],
-         [gl_cv_func_memchr_works=yes],
-         [gl_cv_func_memchr_works=no],
-         [case "$host_os" in
-                             # Guess no on Android.
-            linux*-android*) gl_cv_func_memchr_works="guessing no" ;;
-                             # Guess yes on native Windows.
-            mingw*)          gl_cv_func_memchr_works="guessing yes" ;;
-                             # If we don't know, obey --enable-cross-guesses.
-            *)               gl_cv_func_memchr_works="$gl_cross_guess_normal" ;;
-          esac
-         ])
-      ])
-    case "$gl_cv_func_memchr_works" in
-      *yes) ;;
-      *) REPLACE_MEMCHR=1 ;;
-    esac
-  fi
+       [gl_cv_func_memchr_works=yes],
+       [gl_cv_func_memchr_works=no],
+       [case "$host_os" in
+                           # Guess no on Android.
+          linux*-android*) gl_cv_func_memchr_works="guessing no" ;;
+                           # Guess yes on native Windows.
+          mingw*)          gl_cv_func_memchr_works="guessing yes" ;;
+                           # If we don't know, obey --enable-cross-guesses.
+          *)               gl_cv_func_memchr_works="$gl_cross_guess_normal" ;;
+        esac
+       ])
+    ])
+  case "$gl_cv_func_memchr_works" in
+    *yes) ;;
+    *) REPLACE_MEMCHR=1 ;;
+  esac
 ])
 
 # Prerequisites of lib/memchr.c.
diff --git a/m4/strcasestr.m4 b/m4/strcasestr.m4
index 4c2275fc71..ee2287321d 100644
--- a/m4/strcasestr.m4
+++ b/m4/strcasestr.m4
@@ -1,4 +1,4 @@
-# strcasestr.m4 serial 25
+# strcasestr.m4 serial 26
 dnl Copyright (C) 2005, 2007-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -17,7 +17,7 @@ AC_DEFUN([gl_FUNC_STRCASESTR_SIMPLE],
   if test $ac_cv_func_strcasestr = no; then
     HAVE_STRCASESTR=0
   else
-    if test $HAVE_MEMCHR = 0 || test $REPLACE_MEMCHR = 1; then
+    if test $REPLACE_MEMCHR = 1; then
       REPLACE_STRCASESTR=1
     else
       dnl Detect https://sourceware.org/bugzilla/show_bug.cgi?id=12092
diff --git a/m4/string_h.m4 b/m4/string_h.m4
index cc51337f0d..516b346b31 100644
--- a/m4/string_h.m4
+++ b/m4/string_h.m4
@@ -5,7 +5,7 @@
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-# serial 23
+# serial 24
 
 # Written by Paul Eggert.
 
@@ -87,7 +87,6 @@ AC_DEFUN([gl_HEADER_STRING_H_DEFAULTS],
   HAVE_EXPLICIT_BZERO=1;        AC_SUBST([HAVE_EXPLICIT_BZERO])
   HAVE_FFSL=1;                  AC_SUBST([HAVE_FFSL])
   HAVE_FFSLL=1;                 AC_SUBST([HAVE_FFSLL])
-  HAVE_MEMCHR=1;                AC_SUBST([HAVE_MEMCHR])
   HAVE_DECL_MEMMEM=1;           AC_SUBST([HAVE_DECL_MEMMEM])
   HAVE_MEMPCPY=1;               AC_SUBST([HAVE_MEMPCPY])
   HAVE_DECL_MEMRCHR=1;          AC_SUBST([HAVE_DECL_MEMRCHR])
diff --git a/m4/strstr.m4 b/m4/strstr.m4
index a2ec337f17..529110793c 100644
--- a/m4/strstr.m4
+++ b/m4/strstr.m4
@@ -1,4 +1,4 @@
-# strstr.m4 serial 21
+# strstr.m4 serial 22
 dnl Copyright (C) 2008-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -9,7 +9,7 @@ AC_DEFUN([gl_FUNC_STRSTR_SIMPLE],
 [
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
   AC_REQUIRE([gl_FUNC_MEMCHR])
-  if test $HAVE_MEMCHR = 0 || test $REPLACE_MEMCHR = 1; then
+  if test $REPLACE_MEMCHR = 1; then
     REPLACE_STRSTR=1
   else
     dnl Detect https://sourceware.org/bugzilla/show_bug.cgi?id=12092