From afc0578da2868f99075be48f4291bf13cf3c9b10 Mon Sep 17 00:00:00 2001
From: fxcoudert <fxcoudert@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri, 13 Dec 2013 21:42:02 +0000
Subject: [PATCH] * configure.ac: Add user-friendly check for native
 x86_64-linux multilibs. * configure: Regenerate.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@205975 138bc75d-0d04-0410-961f-82ee72b054a4
---
 ChangeLog    |  6 ++++++
 configure    | 20 ++++++++++++++++++++
 configure.ac | 20 ++++++++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index f66f5523f5..2d78f36277 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2013-12-13  Francois-Xavier Coudert  <fxcoudert@gcc.gnu.org>
+
+	* configure.ac: Add user-friendly check for native x86_64-linux
+	multilibs.
+	* configure: Regenerate.
+
 2013-11-23  Alan Modra  <amodra@gmail.com>
 
 	* config.sub, config.guess: Import from upstream.
diff --git a/configure b/configure
index d4a82137ba..749a35ea0a 100755
--- a/configure
+++ b/configure
@@ -7500,6 +7500,26 @@ if test x${is_cross_compiler} = xyes ; then
   target_configargs="--with-cross-host=${host_noncanonical} ${target_configargs}"
 fi
 
+# Special user-friendly check for native x86_64-linux build, if
+# multilib is not explicitly enabled.
+case "$target:$have_compiler:$host:$target:$enable_multilib" in
+  x86_64-*linux*:yes:$build:$build:)
+    # Make sure we have a developement environment that handles 32-bit
+    dev64=no
+    echo "int main () { return 0; }" > conftest.c
+    ${CC} -m32 -o conftest ${CFLAGS} ${CPPFLAGS} ${LDFLAGS} conftest.c
+    if test $? = 0 ; then
+      if test -s conftest || test -s conftest.exe ; then
+	dev64=yes
+      fi
+    fi
+    rm -f conftest*
+    if test x${dev64} != xyes ; then
+      as_fn_error "I suspect your system does not have 32-bit developement libraries (libc and headers). If you have them, rerun configure with --enable-multilib. If you do not have them, and want to build a 64-bit-only compiler, rerun configure with --disable-multilib." "$LINENO" 5
+    fi
+    ;;
+esac
+
 # Default to --enable-multilib.
 if test x${enable_multilib} = x ; then
   target_configargs="--enable-multilib ${target_configargs}"
diff --git a/configure.ac b/configure.ac
index 30190d65be..b24b33de78 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2879,6 +2879,26 @@ if test x${is_cross_compiler} = xyes ; then
   target_configargs="--with-cross-host=${host_noncanonical} ${target_configargs}"
 fi
 
+# Special user-friendly check for native x86_64-linux build, if
+# multilib is not explicitly enabled.
+case "$target:$have_compiler:$host:$target:$enable_multilib" in
+  x86_64-*linux*:yes:$build:$build:)
+    # Make sure we have a developement environment that handles 32-bit
+    dev64=no
+    echo "int main () { return 0; }" > conftest.c
+    ${CC} -m32 -o conftest ${CFLAGS} ${CPPFLAGS} ${LDFLAGS} conftest.c
+    if test $? = 0 ; then
+      if test -s conftest || test -s conftest.exe ; then
+	dev64=yes
+      fi
+    fi 
+    rm -f conftest*
+    if test x${dev64} != xyes ; then
+      AC_MSG_ERROR([I suspect your system does not have 32-bit developement libraries (libc and headers). If you have them, rerun configure with --enable-multilib. If you do not have them, and want to build a 64-bit-only compiler, rerun configure with --disable-multilib.])
+    fi
+    ;;
+esac
+
 # Default to --enable-multilib.
 if test x${enable_multilib} = x ; then
   target_configargs="--enable-multilib ${target_configargs}"