From a1b880642244b9f732d327e1d93162652838bb06 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Thu, 1 Sep 2011 09:18:16 +0200
Subject: configure.ac: fail if libid3tag was enabled explicitly, but not found

Add M4 function MPD_AUTO_PKG_LIB for pkg-config with AC_CHECK_LIB
fallback.
---
 configure.ac   | 15 +++++----------
 m4/mpd_auto.m4 | 15 +++++++++++++++
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/configure.ac b/configure.ac
index 4de63dac9..74aef61de 100644
--- a/configure.ac
+++ b/configure.ac
@@ -196,9 +196,9 @@ AC_ARG_ENABLE(httpd-output,
 	[enable_httpd_output=auto])
 
 AC_ARG_ENABLE(id3,
-	AS_HELP_STRING([--disable-id3],
-		[disable id3 support (default: enable)]),,
-	enable_id3=yes)
+	AS_HELP_STRING([--enable-id3],
+		[disable id3 support]),,
+	enable_id3=auto)
 
 AC_ARG_ENABLE(inotify,
 	AS_HELP_STRING([--disable-inotify],
@@ -510,13 +510,8 @@ fi
 AM_CONDITIONAL(HAVE_CUE, test x$enable_cue = xyes)
 
 dnl -------------------------------- libid3tag --------------------------------
-if test x$enable_id3 = xyes; then
-	PKG_CHECK_MODULES([ID3TAG], [id3tag],,
-		AC_CHECK_LIB(id3tag, id3_file_open,
-			[ID3TAG_LIBS="-lid3tag -lz" ID3TAG_CFLAGS=""],
-			enable_id3=no))
-fi
-
+MPD_AUTO_PKG_LIB(id3, ID3TAG, id3tag, id3tag, id3_file_open, [-lid3tag -lz], [],
+	[id3tag], [libid3tag not found])
 if test x$enable_id3 = xyes; then
 	AC_DEFINE(HAVE_ID3TAG, 1, [Define to use id3tag])
 fi
diff --git a/m4/mpd_auto.m4 b/m4/mpd_auto.m4
index 3f233938f..23713d5b7 100644
--- a/m4/mpd_auto.m4
+++ b/m4/mpd_auto.m4
@@ -63,3 +63,18 @@ AC_DEFUN([MPD_AUTO_PKG], [
 
 	MPD_AUTO_RESULT([$1], [$4], [$5])
 ])
+
+dnl Check with pkg-config first, fall back to AC_CHECK_LIB.
+dnl
+dnl Parameters: varname1, varname2, pkgname, libname, symname, libs, cflags, description, errmsg
+AC_DEFUN([MPD_AUTO_PKG_LIB], [
+	if eval "test x`echo '$'enable_$1` != xno"; then
+		PKG_CHECK_MODULES([$2], [$3],
+			[eval "found_$1=yes"],
+			AC_CHECK_LIB($4, $5,
+				[eval "found_$1=yes $2_LIBS='$6' $2_CFLAGS='$7'"],
+				[eval "found_$1=no"]))
+	fi
+
+	MPD_AUTO_RESULT([$1], [$8], [$9])
+])
-- 
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