[glibc] Force use of -ffreestanding when checking for gnumach headers

[Samuel Thibault <sthibaul@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=8b8c768e3c701ed1993789bb46acb8a12c7a93df

commit 8b8c768e3c701ed1993789bb46acb8a12c7a93df
Author: Flavio Cruz <flaviocruz@gmail.com>
Date:   Sun Dec 18 19:46:15 2022 -0500

    Force use of -ffreestanding when checking for gnumach headers
    
    Without this ./configure assumes that we are in a fully hosted
    environment, which might not be the case. After this patch, we can rely on
    the freestanding header files provided by GCC such as stdint.h.
    Message-Id: <Y5+0V9osFc/zXMq0@mars>

Diff:
---
 sysdeps/mach/configure    | 8 +++++++-
 sysdeps/mach/configure.ac | 6 ++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/sysdeps/mach/configure b/sysdeps/mach/configure
index 739f1028a4..36f556a663 100644
--- a/sysdeps/mach/configure
+++ b/sysdeps/mach/configure
@@ -133,6 +133,8 @@ if test -n "$sysheaders"; then
 fi
 
 ### Sanity checks for Mach header installation
+old_CFLAGS=$CFLAGS
+CFLAGS="$CFLAGS -ffreestanding"
 
 
 ac_fn_c_check_header_preproc "$LINENO" "mach/mach_types.h" "ac_cv_header_mach_mach_types_h"
@@ -143,6 +145,7 @@ else
 fi
 
 
+CFLAGS=$old_CFLAGS
 ac_fn_c_check_header_preproc "$LINENO" "mach/mach_types.defs" "ac_cv_header_mach_mach_types_defs"
 if test "x$ac_cv_header_mach_mach_types_defs" = xyes; then :
 
@@ -216,7 +219,9 @@ $as_echo_n "checking for creation_time in task_basic_info... " >&6; }
 if ${libc_cv_mach_task_creation_time+:} false; then :
   $as_echo_n "(cached) " >&6
 else
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+  old_CFLAGS=$CFLAGS
+CFLAGS="$CFLAGS -ffreestanding"
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <mach/task_info.h>
 int
@@ -242,6 +247,7 @@ $as_echo "$libc_cv_mach_task_creation_time" >&6; }
 if test $libc_cv_mach_task_creation_time = no; then
   as_fn_error $? "you need Mach headers supporting task_info.creation_time" "$LINENO" 5
 fi
+CFLAGS=$old_CFLAGS
 
 mach_interface_list=
 for ifc in mach mach4 gnumach \
diff --git a/sysdeps/mach/configure.ac b/sysdeps/mach/configure.ac
index 61b00d66b1..5816c3d4ad 100644
--- a/sysdeps/mach/configure.ac
+++ b/sysdeps/mach/configure.ac
@@ -12,8 +12,11 @@ if test -n "$sysheaders"; then
 fi
 
 ### Sanity checks for Mach header installation
+old_CFLAGS=$CFLAGS
+CFLAGS="$CFLAGS -ffreestanding"
 AC_CHECK_HEADER(mach/mach_types.h,,
                 [AC_MSG_ERROR([cannot find Mach headers])], -)
+CFLAGS=$old_CFLAGS
 AC_CHECK_HEADER(mach/mach_types.defs,, [dnl
 AC_MSG_ERROR([cannot find Mach .defs files])], -)
 
@@ -42,6 +45,8 @@ dnl The creation_time field is a GNU Mach addition the other variants lack.
 dnl
 AC_CACHE_CHECK(for creation_time in task_basic_info,
 	       libc_cv_mach_task_creation_time, [dnl
+old_CFLAGS=$CFLAGS
+CFLAGS="$CFLAGS -ffreestanding"
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <mach/task_info.h>]], [[
 extern struct task_basic_info *i;
 long s = i->creation_time.seconds;
@@ -49,6 +54,7 @@ long s = i->creation_time.seconds;
 if test $libc_cv_mach_task_creation_time = no; then
   AC_MSG_ERROR([you need Mach headers supporting task_info.creation_time])
 fi
+CFLAGS=$old_CFLAGS
 
 dnl
 dnl The Darwin variant no longer has <mach/mach.defs>