[2661] protect the output of 'python-config | sed' with [], with more comments.

without [] the output it seems possible that the output is empty for some
environments.  also clarified that we can ignore the cases where -L isn't
contained at all.

diff --git a/configure.ac b/configure.ac
index fad1e2082367cb8b57ae6850961cb33cf4a20467..df0fd695d56e1d136c4daa35cfc4b2c65ef99aa8 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -298,12 +298,16 @@ AC_SUBST(COMMON_PYTHON_PATH)
 if test -x ${PYTHON}-config; then
        PYTHON_INCLUDES=`${PYTHON}-config --includes`
 
-       # make a copy of python-config --ldflags, removing any spaces and tabs
+       # Add any '-L..." flags to PYTHON_LDFLAGS.  We first make a copy of
+       # python-config --ldflags, removing any spaces and tabs
        # between "-L" and its argument (some instances of python-config
-       # insert a space, which would confuse the code below)
-       python_config_ldflags=`${PYTHON}-config --ldflags | sed -ne 's/\([ \t]*-L\)[ ]*\([^ \t]*[ \t]*\)/\1\2/pg'`
+       # insert a space, which would confuse the code below).
+       # Notes: if -L isn't contained at all we can simply skip this process,
+       # so we only go through the flag if it's contained; also, protecting
+       # the output with [] seems necessary for environment to avoid getting
+       # an empty output accidentally.
+       python_config_ldflags=[`${PYTHON}-config --ldflags | sed -ne 's/\([ \t]*-L\)[ ]*\([^ \t]*[ \t]*\)/\1\2/pg'`]
        for flag in $python_config_ldflags; do
-               # add any '-L..." flags to PYTHON_LDFLAGS
                flag=`echo $flag | sed -ne 's/^\(\-L.*\)$/\1/p'`
                if test "X${flag}" != X; then
                        PYTHON_LDFLAGS="$PYTHON_LDFLAGS ${flag}"