Fix bad interaction between sysroot and C++ include dir

Message ID 1946944.q1On1cTmB7@polaris
State New
Headers show
  • Fix bad interaction between sysroot and C++ include dir
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Commit Message

Eric Botcazou May 10, 2018, 9:36 a.m.
This fixes an annyoing regression introduced in 2012 by this change:

The idea of the change is to interpolate the value passed to --with-sysroot in 
the value passed to --with-gxx-include-dir, so that you can change the sysroot 
at run time, i.e. pass --sysroot to the compiler, and have the gxx-include-dir 
automatically translated relatively to the new sysroot.

The original submission did just that:
but it was probably done against a branch so the version eventually installed 
does the interpolation unconditionally, i.e. even when gxx-include-dir is the 
default C++ include path in the install tree.

The result is that, if you configure --with-sysroot with a value that happens 
to be identical to the start of the default C++ path in the install tree, the 
mechanism triggers and the C++ include path is completely broken if you pass 
--sysroot to the compiler.  IOW the same issue as the one meant to be fixed, 
but this time when --with-gxx-include-dir is not passed.

So the attached patch restores the original implementation by doing the 
interpolation only when both --with-sysroot and --with-gxx-include-dir are 
specified on the configure line.

Tested on x86-64/Linux, applied on the mainline as obvious.

2018-05-10  Eric Botcazou  <>

	* (gcc_gxx_include_dir_add_sysroot): Set it to 1 only
	when --with-gxx-include-dir is also specified.
	* configure: Regenerate.


---	(revision 260071)
+++	(working copy)
@@ -205,6 +205,11 @@  no)	;;
 *)	gcc_gxx_include_dir=$with_gxx_include_dir ;;
+# If both --with-sysroot and --with-gxx-include-dir are passed, we interpolate
+# the former in the latter and, upon success, compute gcc_gxx_include_dir as
+# relative to the sysroot.
 # This logic must match libstdc++-v3/acinclude.m4:GLIBCXX_EXPORT_INSTALL_INFO.
 if test x${gcc_gxx_include_dir} = x; then
   if test x${enable_version_specific_runtime_libs} = xyes; then
@@ -216,15 +221,10 @@  if test x${gcc_gxx_include_dir} = x; the
-if test "${with_sysroot+set}" = set; then
+elif test "${with_sysroot+set}" = set; then
   gcc_gxx_without_sysroot=`expr "${gcc_gxx_include_dir}" : "${with_sysroot}"'\(.*\)'`
   if test "${gcc_gxx_without_sysroot}"; then
-    if test x${with_sysroot} != x/; then
-      gcc_gxx_include_dir="${gcc_gxx_without_sysroot}"
-    fi
+    gcc_gxx_include_dir="${gcc_gxx_without_sysroot}"