[PATCH 2/4] package: don't regen the parser during dist if unneeded

[Akim Demaille]

* Makefile.am (gen-synclines): New.
---
 Makefile.am | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index 3c4c8765..f6350ac2 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -88,9 +88,21 @@ clean-local:
 BUILT_SOURCES += $(top_srcdir)/.version
 $(top_srcdir)/.version: configure
        echo $(VERSION) > address@hidden && mv address@hidden $@
-dist-hook: gen-ChangeLog
+dist-hook: gen-ChangeLog gen-synclines
        echo $(VERSION) > $(distdir)/.tarball-version
-       cd $(distdir) && $(abs_top_builddir)/tests/bison 
$(AM_YFLAGS_WITH_LINES) src/parse-gram.y -o src/parse-gram.c
+
+# When generating a release, include the #lines in Bison's parser.  Do it
+# only if needed.  In particular, distcheck runs dist with read-only
+# sources, so don't try to update src/parse-gram.c: we don't have the
+# permissions.
+.PHONY: gen-synclines
+gen-synclines:
+       cd $(distdir) &&                                                \
+       if ! grep '#line' src/parse-gram.c >/dev/null 2>&1; then        \
+         $(abs_top_builddir)/tests/bison                               \
+           $(AM_YFLAGS_WITH_LINES) src/parse-gram.y                    \
+           -o src/parse-gram.c;                                        \
+       fi
 
 .PHONY: update-b4-copyright update-package-copyright-year
 update-b4-copyright:
-- 
2.21.0