From f85cd0174e629375bb79f13cda713e3ee810b49f Mon Sep 17 00:00:00 2001
From: Ulya Trofimovich <skvadrik@gmail.com>
Date: Tue, 29 Jul 2014 17:53:49 +0300
Subject: [PATCH] Enable 'make docs' only if configured with '--enable-docs'.

./configure --enable-docs checks for asciidoc and a2x
---
 re2c/Makefile.am  | 22 +++++++++-------------
 re2c/configure.ac | 15 +++++++++++----
 2 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/re2c/Makefile.am b/re2c/Makefile.am
index a7b4ae36..708cc117 100755
--- a/re2c/Makefile.am
+++ b/re2c/Makefile.am
@@ -21,12 +21,6 @@ RE2C         = re2c$(EXEEXT)
 RE2CFLAGS    = -bi
 
 CLEANFILES = parser.cc y.tab.c y.tab.h scanner.cc .version
-if HAVE_ASCIIDOC
-    CLEANFILES += htdocs/manual.html
-endif HAVE_ASCIIDOC
-if HAVE_A2X
-    CLEANFILES += re2c.1
-endif HAVE_A2X
 
 DISTCLEANFILES = makerpm re2c.spec README scanner.cc re2c$(EXEEXT)
 
@@ -101,12 +95,14 @@ vtests: all $(TESTS)
 	test -x $(TESTS) || chmod +x $(TESTS)
 	./$(TESTS) --valgrind
 
+if REBUILD_DOCS
 docs: $(DOCS)
 $(DOCS): re2c.ad
-	@if test $(A2X) = "yes"; then \
-		a2x -f manpage re2c.ad; \
-	fi
-	@if test $(ASCIIDOC) = "yes"; then \
-		mkdir -p htdocs; \
-		asciidoc -o htdocs/manual.html re2c.ad; \
-	fi
+	a2x -f manpage re2c.ad
+	mkdir -p htdocs
+	asciidoc -o htdocs/manual.html re2c.ad
+else
+docs:
+	@echo "Reconfigure to rebuild docs: ./configure --enable-docs"
+	@exit 1
+endif
diff --git a/re2c/configure.ac b/re2c/configure.ac
index 9cac446c..1d226152 100644
--- a/re2c/configure.ac
+++ b/re2c/configure.ac
@@ -16,10 +16,17 @@ AC_CHECK_PROG(BISON, bison, yes, no)
 AC_PROG_CXX
 AC_PROG_CC
 AC_PROG_INSTALL
-AC_CHECK_PROG(ASCIIDOC, asciidoc, yes, no)
-AM_CONDITIONAL(HAVE_ASCIIDOC, [test "$ASCIIDOC" = yes])
-AC_CHECK_PROG(A2X, a2x, yes, no)
-AM_CONDITIONAL(HAVE_A2X, [test "$A2X" == yes])
+
+dnl --enable-docs
+AC_ARG_ENABLE([docs], [AS_HELP_STRING([--enable-docs], [regenerate man page and online documentation])])
+AM_CONDITIONAL([REBUILD_DOCS], [test "x$enable_docs" = "xyes"])
+AM_COND_IF([REBUILD_DOCS], [
+  AC_CHECK_PROG(ASCIIDOC, asciidoc, yes, no)
+  AC_CHECK_PROG(A2X, a2x, yes, no)
+  AS_IF([test "x$ASCIIDOC" = "xno" -o "x$A2X" = "xno"], [
+      AC_MSG_ERROR([need asciidoc and a2x for --enable-docs])
+  ])
+])
 
 if test "$GCC" = "yes"; then
   AC_MSG_CHECKING([Testing GCC version])
-- 
2.40.0