+# The flex/bison rules refrain from updating unchanged headers for the
+# convenience of developers, but the headers must be distributed with
+# up-to-date timestamps, otherwise make will try to update them in a fresh
+# VPATH build.
+dist-hook: update-headers
+update-headers:
+ touch -c '$(distdir)/src/scan.h'
+ touch -c '$(distdir)/src/parse.h'
+