Bug 1142420 - Require that the same compiler version be used for C and C++ (at the very least, so that our version checks are valid for both). r=glandium

I tested locally that both checks give the expected error if I
temporarily change the != to an =.

--HG--
extra : transplant_source : %01N%B9%8B%BC%1E%07%D6%AE%BA2%7B%87%FB%25Y%19%B6%A9%D3

build/autoconf/toolchain.m4

@@ -34,6 +34,12 @@ EOF
 if test "$compiler" != "$cxxcompiler"; then
     AC_MSG_ERROR([Your C and C++ compilers are different.  You need to use the same compiler.])
 fi
+if test "$CC_VERSION" != "$CXX_VERSION"; then
+    # This may not be strictly necessary, but if we want to drop it, we
+    # should make sure any version checks below apply to both the C and
+    # C++ compiler versions.
+    AC_MSG_ERROR([Your C and C++ compiler versions are different.  You need to use the same compiler version.])
+fi
 CC_VERSION=`echo "$CC_VERSION" | sed 's/ //g'`
 CXX_VERSION=`echo "$CXX_VERSION" | sed 's/ //g'`
 if test "$compiler" = "gcc"; then
@@ -238,6 +244,12 @@ EOF
     if test "$host_compiler" != "$host_cxxcompiler"; then
         AC_MSG_ERROR([Your C and C++ host compilers are different.  You need to use the same compiler.])
     fi
+    if test "$HOST_CC_VERSION" != "$HOST_CXX_VERSION"; then
+        # This may not be strictly necessary, but if we want to drop it,
+        # we should make sure any version checks below apply to both the
+        # C and C++ compiler versions.
+        AC_MSG_ERROR([Your C and C++ host compiler versions are different.  You need to use the same compiler version.])
+    fi
     if test -n "$host_compiler"; then
         if test "$host_compiler" = "GCC" ; then
             changequote(<<,>>)