----- Original Message ----- > From: "Paul Smith" <psm...@gnu.org> > To: "Renaud Pacalet" <renaud.paca...@telecom-paris.fr>, help-make@gnu.org > Sent: Thursday, May 29, 2025 2:59:04 PM > Subject: Re: patsubst strange behavior when substituting the empty string
> On Thu, 2025-05-29 at 09:43 +0200, Renaud Pacalet wrote: >> I recently observed a strange `patsubst` behavior when substituting >> the empty string: >> >> ``` >> $ cat Makefile >> >> .PHONY: all >> all:; >> $(info $(patsubst %.,,1.2)) >> >> $ make >> 1.2 >> make: Nothing to be done for 'all'. >> ``` >> >> I read the manual twice but I cannot explain this behavior. What did >> I miss? > > When using patsubst the pattern must match the _entire_ word. If the > pattern doesn't match the word, then the word is not changed. > > Here, "%." does not match the word "1.2". It would work if you used > "%.2" as the pattern, like: > > $ echo '$(info $(patsubst %.2,2,1.2))' | make -f- > 2 > make: *** No targets. Stop. > > > If it were possible to have multiple match characters then you could do > something like "%.%" but that is not possible. > > Without knowing what you're actually trying to do, I can't suggest an > alternative that might work for you. Ah, I forgot the _entire_ word part. The alternative is probably a combination of `subst` and `word`: `$(word 2,$(subst ., ,1.2))`. Thanks a lot Paul. -- Renaud Pacalet Télécom Paris Campus SophiaTech 450 Route des Chappes, CS 50193 06904 Biot Sophia Antipolis cedex, FRANCE Tel : +33 (0) 4 9300 8402 Web : http://www.telecom-paris.fr/
