Hi Akim. On 02/20/2012 02:24 PM, Akim Demaille wrote: > I am having problems in Bison (current master) to recover > from a lost parse-gram.h, generated from parse-gram.y > with regular Automake (1.11.3) handling: > >> AM_YFLAGS = -d -v --warnings=all,error --report=all >> >> src_bison_SOURCES = \ >> ... >> src/output.h \ >> src/parse-gram.y \ >> src/print-xml.c \ >> ... > > > Makefile.in: > >> src/parse-gram.h: src/parse-gram.c >> @if test ! -f $@; then rm -f src/parse-gram.c; else :; fi >> @if test ! -f $@; then $(MAKE) $(AM_MAKEFLAGS) src/parse-gram.c; else >> :; fi > > The problem is that src/parse-gram.c is in $(srcdir), so > its occurrences in the commands should be prefixed by > $(srcdir)/. Actually, I don't understand why we don't > simply use $< (lemme guess: it's not portable for non > generic recipes, > Exactly; see the first node here:
http://www.gnu.org/software/autoconf/manual/html_node/Portable-Make.html > ISTR some horrors in this area that my brains decided to quickly forget :). > ;-) > Also, why two "if"? > For the sake of "make -n": at least GNU make and Solaris make execute recipes containing the $(MAKE) string even when they are running in dry mode; so if we didn't break the recipe above in two invocations, the file 'src/parse-gram.c' would be removed even upon "make -n". Not nice. > In case some concurrent execution of Make would already have > provided $@ in the meanwhile? > Nope; see above. > The following patch extends a test which is aimed at checking > this, but does it in a non-vpath build :) > But the test is wrong, because it checks that the Yacc-generated .h and .c files are placed in the $srcdir, while we expect them to be placed in the $builddir. Do the tests added by your patch work for you? They don't work for me (as I would have expected BTW). > I have a question though. I don't understand how come > Make realizes it must provide $@ in srcdir too. > > The Makefile.in features: > >> .y.c: >> $(AM_V_YACC)$(am__skipyacc) $(SHELL) $(YLWRAP) $< y.tab.c $@ y.tab.h >> $*.h y.output $*.output -- $(YACCCOMPILE) > > and at runtime I have: > >> /bin/sh ../../build-aux/ylwrap ../../src/parse-gram.y y.tab.c >> ../../src/parse-gram.c y.tab.h ../../src/parse-gram.h y.output >> ../../src/parse-gram.output -- ./tests/bison -y -d -v --warnings=all,error >> --report=all >> updating ../../src/parse-gram.h >> ../../src/parse-gram.output is unchanged > > which is what is expected, but I don't understand why > it works: that $< is prefixed with $(srcdir), this I > understand, but why does it appear on $@? > Unless I'm somehow sorely mistaken, that is not automake's doing; it's the make implementation that does such a rewrite. Which is highly unexpected BTW. Which make implementation are you using? > I have to specify $(srcdir)/ by hand on similar patterns, > why does it work here? > No idea. Regards, Stefano
