On 05/11/2020 21:48, Junio C Hamano wrote: > Ramsay Jones <ramsay@xxxxxxxxxxxxxxxxxxxx> writes: > >> [Yes, 'cd Documentation; make clean all' will be slower that a doing >> separate 'make clean; make', but the extra 10s, or so, will be swamped >> by the documentation build time! ;-) ] > > Hmph, the "all" part in "make clean all" needs the information we > read from these generated files, and time must be spent to generate > them whether "make clean all" or "make clean; make all" is used. In > the latter, we may not generate and read them in the first phase, > but the second one "make all" would need to do so anyway. So I am > puzzled why "make clean all" needs to be slower---don't we generate > and read them only once in either case? > Hmm, interesting. I was all ready to explain the results of the moc-up of this that I did about a month ago, but thought I should just check again ... ;-) This time I used the actual Makefile, rather than a moc-up, and got different (in some sense, worse) results. What I was going to say was, no the doc.dep file gets generated twice - but that is not true. :( However, if you run 'make clean all', you will not be pleased with the results! $ make clean ... $ make clean all >zzz 2>&1 $ grep WARNING zzz | wc -l 26 $ tail -1 zzz make: *** [Makefile:362: git.1] Error 13 $ If you look at the output, you will see that, while processing the 'clean' target, the 'doc.dep' file is created, -included, and then immediately deleted. While processing the 'all' target I had expected the 'doc.dep' file to be recreated - but it isn't. It seems to have done the 'drop the internal data, re-read and re-parse' only the once, and on the second go round (because it has already generated it once) does not re-create and re-read the dependency data again. Thus, the 'all' target is executed without any 'doc.dep' data and falls over in a heap. :( [BTW, just doing 'make' does not do a full build. I will look at why that is later]. Doing 'make clean; make all' works fine, of course. That will teach me to cut corners! Ho-Hum. Sorry about that. Thanks. ATB, Ramsay Jones
