1 1.3 rillig # $NetBSD: use-inference.mk,v 1.3 2020/12/07 00:53:30 rillig Exp $ 2 1.1 rillig # 3 1.1 rillig # Demonstrate that .USE rules do not have an effect on inference rules. 4 1.1 rillig # At least not in the special case where the inference rule does not 5 1.1 rillig # have any associated commands. 6 1.1 rillig 7 1.1 rillig .SUFFIXES: 8 1.1 rillig .SUFFIXES: .from .to 9 1.1 rillig 10 1.1 rillig all: use-inference.to 11 1.1 rillig 12 1.1 rillig verbose: .USE 13 1.1 rillig @echo 'Verbosely making $@ out of $>' 14 1.1 rillig 15 1.1 rillig .from.to: verbose 16 1.1 rillig # Since this inference rule does not have any associated commands, it 17 1.1 rillig # is ignored. 18 1.1 rillig # 19 1.1 rillig # @echo 'Building $@ from $<' 20 1.1 rillig 21 1.1 rillig use-inference.from: # assume it exists 22 1.1 rillig @echo 'Building $@ from nothing' 23 1.1 rillig 24 1.1 rillig # Possible but unproven explanation: 25 1.1 rillig # 26 1.1 rillig # The main target is "all", which depends on "use-inference.to". 27 1.1 rillig # The inference connects the .from to the .to file, otherwise make 28 1.1 rillig # would not know that the .from file would need to be built. 29 1.1 rillig # 30 1.1 rillig # The .from file is then built. 31 1.1 rillig # 32 1.1 rillig # After this, make stops since it doesn't know how to make the .to file. 33 1.1 rillig # This is strange since make definitely knows about the .from.to suffix 34 1.1 rillig # inference rule. But it seems to ignore it, maybe because it doesn't 35 1.1 rillig # have any associated commands. 36 1.2 rillig 37 1.3 rillig # Until 2020-12-07, despite the error message "don't know how to make", 38 1.3 rillig # the exit status was 0. This was inconsistent. 39
Indexes created Sat Sep 20 22:09:52 GMT 2025