From 50e8259639936c867c486917aba8d9f748a35d2c Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Fri, 24 Feb 2023 07:38:19 -0500
Subject: build: Use AC_CONFIG_SUBDIRS()

But explain why Automake's SUBDIRS can't be used.

Also, exclude instructions to generate files from generated files.
---
diff --git a/3rdparty/local.mk b/3rdparty/local.mk
index 2fcd50b..40a8490 100644
--- a/3rdparty/local.mk
+++ b/3rdparty/local.mk
@@ -1,8 +1,19 @@
 if EMBEDDED_XCF2PNG
+## Yes, SUBDIRS should be used instead, except that these lines are still needed
+## in case boukengine's default verbosity differs from that of xcftools:
 VV   = $(VV_$(V))
 VV_  = $(AM_DEFAULT_VERBOSITY)
 VV_1 = 1
 VV_0 = 0
+## Plus this is needed:
+##     AM_MAKEFLAGS = V=$(VV)
+## But this is still not enough, for two reasons:
+##  1. xcftools needs a "distdir" target [1] in its makefile, which would mean
+##     copying the source tree, which xcftools currently avoids with a symbolic
+##     link and manifest file, and
+##  2. Installing boukengine also installs xcftools, which is unnecessary.
+## [1]:
+##    https://gnu.org/s/automake/manual/html_node/Third_002dParty-Makefiles.html
 $(XCF2PNG):
 	$(AM_V_at)(cd %reldir%/xcftools/ && $(MAKE) V=$(VV))
 clean-local:
diff --git a/Makefile.am b/Makefile.am
index 83ff962..2465627 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,4 +1,4 @@
-# Process this file with automake to produce an input makefile.
+## Process this file with automake to produce an input makefile.
 #
 # Copyright (C) 2013  Patrick "P. J." McDermott
 #
diff --git a/configure.ac b/configure.ac
index 2fac9ae..8767989 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,4 +1,4 @@
-# Process this file with autoconf to produce a configure script.
+dnl Process this file with autoconf to produce a configure script.
 #
 # Copyright (C) 2013  Patrick "P. J." McDermott
 #
@@ -68,7 +68,6 @@ AC_ARG_WITH(
 				;;
 			*)
 				XCF2PNG="${withval}"
-				AC_SUBST([XCF2PNG])
 				embedded_xcf2png=false
 				;;
 		esac
@@ -78,15 +77,11 @@ AC_ARG_WITH(
 	]
 )
 if ${embedded_xcf2png}; then
-	AS_MKDIR_P([3rdparty/xcftools])
+	AC_CONFIG_SUBDIRS([3rdparty/xcftools])
 	XCF2PNG='3rdparty/xcftools/xcf2png$(EXEEXT)'
-	abs_srcdir="$(cd "${srcdir}" && pwd)"
-	(
-		cd 3rdparty/xcftools
-		"${SHELL}" "${abs_srcdir}/3rdparty/xcftools/configure"
-	)
 fi
 AM_CONDITIONAL([EMBEDDED_XCF2PNG], [${embedded_xcf2png}])
+AC_SUBST([XCF2PNG])
 
 if test "x$GCC" = "xyes"; then
 	GCC_CFLAGS="-pedantic -Wall -Wextra -Werror"
--
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