[mm-common] Do not substitute zero-length documentation prefix

[Daniel Elstner <daniel src gnome org>]

commit f131d51694171076c7b5a8c42a3730a269de2b35
Author: Daniel Elstner <danielk openismus com>
Date:   Tue Aug 11 13:17:27 2009 +0200

    Do not substitute zero-length documentation prefix
    
    * macros/mm-doc.m4 (_MM_ARG_WITH_TAGFILE_DOC): Correctly test whether
    the location prefix given for a tag file is set, and do not assign an
    empty prefix to a tag file in the @DOXYGEN_TAGFILES@ output variable.
    For the $(DOCINSTALL_FLAGS) list, omit the flag altogether if no path
    can be substituted.

 macros/mm-doc.m4 |   15 ++++++++++-----
 1 files changed, 10 insertions(+), 5 deletions(-)
---
diff --git a/macros/mm-doc.m4 b/macros/mm-doc.m4
index a8cd11f..0552913 100644
--- a/macros/mm-doc.m4
+++ b/macros/mm-doc.m4
@@ -182,12 +182,17 @@ m4_ifval([$3], [dnl
   AS_IF([test "x$USE_MAINTAINER_MODE" != xno && test ! -f "$mm_tagpath"],
         [AC_MSG_WARN([Doxygen tag file $2 not found])])
   AS_IF([test "x$mm_htmlrefdir" = x],
-        [AC_MSG_WARN([Location of external $1 documentation not set])])[]dnl
+        [AC_MSG_WARN([Location of external $1 documentation not set])],
+        [AS_IF([test "x$DOCINSTALL_FLAGS" = x],
+               [DOCINSTALL_FLAGS="-l '$mm_tagname $mm_htmlrefdir'"],
+               [DOCINSTALL_FLAGS="$DOCINSTALL_FLAGS -l '$mm_tagname $mm_htmlrefdir'"])])
 
-  test "x$DOXYGEN_TAGFILES" = x || DOXYGEN_TAGFILES="$DOXYGEN_TAGFILES "
-  DOXYGEN_TAGFILES=$DOXYGEN_TAGFILES[\]"$mm_tagpath=$[mm_htmlref]m4_ifval([$3], [pub], [dir])[\]"
-  test "x$DOCINSTALL_FLAGS" = x || DOCINSTALL_FLAGS="$DOCINSTALL_FLAGS "
-  DOCINSTALL_FLAGS=$DOCINSTALL_FLAGS"-l '$mm_tagname $mm_htmlrefdir'"dnl
+  AS_IF([test "x$[mm_htmlref]m4_ifval([$3], [pub], [dir])" = x],
+        [mm_val=$mm_tagpath],
+        [mm_val="$mm_tagpath=$[mm_htmlref]m4_ifval([$3], [pub], [dir])"])
+  AS_IF([test "x$DOXYGEN_TAGFILES" = x],
+        [DOXYGEN_TAGFILES=[\]"$mm_val[\]"],
+        [DOXYGEN_TAGFILES="$DOXYGEN_TAGFILES "[\]"$mm_val[\]"])[]dnl
 ])
 
 ## MM_ARG_WITH_TAGFILE_DOC(tagfilename, [module])