From 8ee53e2a2804a7cecda91a5e249aa29e6c18f65a Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 6 Apr 2015 16:09:39 -0700
Subject: build: improve pkg-config doc and error handling

Error-handling improvement suggested by Mike Frysinger in:
http://bugs.gnu.org/16757#29
* NEWS: Document pkg-config changes.
* README-prereq: pkg-config is now a prereq when building from
repository.
* m4/pcre.m4 (gl_FUNC_PCRE): Report an error if pcre is explicitly
requested but not available.  Defer to user-supplied PCRE_CFLAGS
and PCRE_LIBS.
---
 m4/pcre.m4 | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

(limited to 'm4')

diff --git a/m4/pcre.m4 b/m4/pcre.m4
index 37de4c53..0effc539 100644
--- a/m4/pcre.m4
+++ b/m4/pcre.m4
@@ -14,16 +14,14 @@ AC_DEFUN([gl_FUNC_PCRE],
        yes|no) test_pcre=$enableval;;
        *) AC_MSG_ERROR([invalid value $enableval for --disable-perl-regexp]);;
      esac],
-    [test_pcre=yes])
+    [test_pcre=maybe])
 
-  PCRE_CFLAGS=
-  PCRE_LIBS=
   AC_SUBST([PCRE_CFLAGS])
   AC_SUBST([PCRE_LIBS])
   use_pcre=no
 
-  if test $test_pcre = yes; then
-    PKG_CHECK_MODULES([PCRE], [libpcre], [], [PCRE_LIBS=-lpcre])
+  if test $test_pcre != no; then
+    PKG_CHECK_MODULES([PCRE], [libpcre], [], [: ${PCRE_LIBS=-lpcre}])
 
     AC_CACHE_CHECK([for pcre_compile], [pcre_cv_have_pcre_compile],
       [pcre_saved_CFLAGS=$CFLAGS
@@ -42,8 +40,10 @@ AC_DEFUN([gl_FUNC_PCRE],
 
     if test "$pcre_cv_have_pcre_compile" = yes; then
       use_pcre=yes
-    else
+    elif test $test_pcre = maybe; then
       AC_MSG_WARN([AC_PACKAGE_NAME will be built without pcre support.])
+    else
+      AC_MSG_ERROR([pcre support not available])
     fi
   fi
 
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