Re: [Qemu-devel] [PATCH] Improve gcc 3 checking

[Anthony Liguori <aliguori@cs.utexas.edu>]

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Paul Brook wrote:
> On Tuesday 19 December 2006 02:25, Anthony Liguori wrote:
>   
>> +gcc3_list="gcc32 gcc33 gcc34 gcc-3.2 gcc-3.3 gcc-3.4"
>>     
>
> Shouldn't we be preferring newer compilers?
>   

Attached patch changes order plus improves the initial GCC 4 check a bit.

>> +       echo "Looking for gcc 3.x"
>>     
>
> We shouldn't do this if if the user explicitly specified a compiler.
> Replacing explicit user setting with guesses is bad.
>   

This stuff kicks in only if the user doesn't specific 
--disable-gcc-check and CC is not GCC 4.

So if the user specific a valid --cc=, then this check won't get triggered.

If they explicitly specific an invalid --cc=, the checks will get 
triggered (but in the past, we would have bailed).

So, if the user wants to explicitly specify a compiler, they can happily 
do that.

Regards,

Anthony Liguori


> Paul
>
>
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> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>   


[-- Attachment #2: qemu-gcc-3x.diff --]
[-- Type: text/x-patch, Size: 2047 bytes --]

diff -r f928121a13c1 configure
--- a/configure	Mon Dec 18 20:29:34 2006 -0600
+++ b/configure	Mon Dec 18 20:54:20 2006 -0600
@@ -22,6 +22,7 @@ static="no"
 static="no"
 cross_prefix=""
 cc="gcc"
+gcc3_list="gcc-3.4 gcc34 gcc-3.3 gcc33 gcc-3.2 gcc32"
 host_cc="gcc"
 ar="ar"
 make="make"
@@ -311,6 +312,41 @@ if test "$mingw32" = "yes" ; then
     oss="no"
     if [ "$cpu" = "i386" ] ; then
         kqemu="yes"
+    fi
+fi
+
+# Check for gcc4, error if pre-gcc4 
+if test "$check_gcc" = "yes" ; then
+    cat > $TMPC <<EOF
+#if __GNUC__ < 4
+#error gcc3
+#endif
+int main(){return 0;}
+EOF
+    check_cc() {
+	which "$1" >&/dev/null
+	return $?
+    }
+
+    if "$cc" -o $TMPE $TMPC 2>/dev/null ; then
+	echo "WARNING: \"$cc\" looks like gcc 4.x"
+	echo "Looking for gcc 3.x"
+	found_compat_cc="no"
+	for compat_cc in $gcc3_list ; do
+	    if check_cc "$compat_cc" ; then
+		echo "Found \"$compat_cc\""
+		cc="$compat_cc"
+		found_compat_cc="yes"
+		break
+	    fi
+	done
+	if test "$found_compat_cc" = "no" ; then
+	    echo "gcc 3.x not found!"
+	    echo "QEMU is known to have problems when compiled with gcc 4.x"
+	    echo "It is recommended that you use gcc 3.x to build QEMU"
+	    echo "To use this compiler anyway, configure with --disable-gcc-check"
+	    exit 1;
+	fi
     fi
 fi
 
@@ -414,23 +450,6 @@ have_gcc3_options="no"
 have_gcc3_options="no"
 if $cc -fno-reorder-blocks -fno-optimize-sibling-calls -o $TMPO $TMPC 2> /dev/null ; then
    have_gcc3_options="yes"
-fi
-
-# Check for gcc4, error if pre-gcc4 
-if test "$check_gcc" = "yes" ; then
-    cat > $TMPC <<EOF
-#if __GNUC__ < 4
-#error gcc3
-#endif
-int main(){return 0;}
-EOF
-    if $cc -o $TMPO $TMPC 2>/dev/null ; then
-        echo "ERROR: \"$cc\" looks like gcc 4.x"
-        echo "QEMU is known to have problems when compiled with gcc 4.x"
-        echo "It is recommended that you use gcc 3.x to build QEMU"
-        echo "To use this compiler anyway, configure with --disable-gcc-check"
-        exit 1;
-    fi
 fi
 
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