Bram Matthys brought my attention to a libtool peculiarity where detecting

things such as C++ compiler actually is a bad thing and since we don't need
that detection I added a work-around, much inspired by a previous patch by
Paolo Bonzini. This also shortens the configure script quite a lot.

1 files changed, 36 insertions, 0 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index 64804dc..9a5c7e7 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -826,3 +826,39 @@ else
 fi
 ])
 
+# Prevent libtool for checking how to run C++ compiler and check for other
+# tools we don't want to use. We do this by m4-defining the _LT_AC_TAGCONFIG
+# variable to the code to run, as by default it uses a much more complicated
+# approach. The code below that is actually added seems to be used for cases
+# where configure has trouble figuring out what C compiler to use but where
+# the installed libtool has an idea.
+#
+# This function is a re-implemented version of the Paolo Bonzini fix posted to
+# the c-ares mailing list by Bram Matthys on May 6 2006. My version removes
+# redundant code but also adds the LTCFLAGS check that wasn't in that patch.
+#
+# Some code in this function was extracted from the generated configure script.
+#
+# CARES_CLEAR_LIBTOOL_TAGS
+AC_DEFUN([CARES_CLEAR_LIBTOOL_TAGS],
+  [m4_define([_LT_AC_TAGCONFIG], [
+  if test -f "$ltmain"; then
+    if test ! -f "${ofile}"; then
+      AC_MSG_WARN([output file `$ofile' does not exist])
+    fi
+
+    if test -z "$LTCC"; then
+      eval "`$SHELL ${ofile} --config | grep '^LTCC='`"
+      if test -z "$LTCC"; then
+        AC_MSG_WARN([output file `$ofile' does not look like a libtool
+script])
+      else
+        AC_MSG_WARN([using `LTCC=$LTCC', extracted from `$ofile'])
+      fi
+    fi
+    if test -z "$LTCFLAGS"; then
+      eval "`$SHELL ${ofile} --config | grep '^LTCFLAGS='`"
+    fi
+  fi
+  ])]
+)