Hello, On 2012-12-06 16:41 +0100, Theophile Ranquet wrote: > I am seeking advice for a workaround of what seems like a limitation > in Automake (1.12.2). > > We have recently added figures to Bison's documentation. These figures > are included by our texinfo source by using "@image", which requires > different image formats depending on what we want to produce. For > convenience's sake, these figures are generated from Graphviz DOT > files, so we tried adding the following to our doc/local.mk: > > doc/bison.dvi: $(FIGS_DOT:.dot=.eps) > doc/bison.html: $(FIGS_DOT:.dot=.png) > doc/bison.pdf: $(FIGS_DOT:.dot=.pdf) > > However, these overwrite Automake's rules. This seems a bit similar, > in that regard, to the issue discussed here: > http://lists.gnu.org/archive/html/automake/2012-11/msg00015.html
The usual workaround to add prerequisites to an automake-generated rule is to use a one-off make variable for the target name. For example, doc_bison_dvi = doc/bison.dvi $(doc_bison_dvi): $(FIGS_DOT:.dot=.eps) and so on. Automake does a simple string comparison of the target name to decide whether or the generated rule is overridden, so using a variable will hide the "real" target name from this check. Note that this is only appropriate for rules with no commands. > (Note that in another branch we are using multiple Makefiles, and in > that branch adding the previous lines to our doc/Makefile.am has the > desired effect, though I am not sure why... is this a bug or a > feature?) Hard to say without looking a concrete example, but the most likely explanation is that the Automake-generated rules are different in the recursive case, such that your custom rules don't actually override anything. Hope that helps, -- Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)
