Is there a case (common or rare) where the answer to this question has real world consequences?
regards, Mark > Am 27.09.2023 um 12:17 schrieb Renaud Pacalet > <renaud.paca...@telecom-paris.fr>: > > Dear all, > > I read the manual carefully (especially section 4.11 "Multiple Rules for One > Target") and searched the help-make archives but couldn't find a clear > description of how $^ and $< are computed when there are several rules for > the same target and only one has a recipe. > > According the manual "All the prerequisites mentioned in all the rules are > merged into one list of prerequisites for the target". But when the recipe > gets expanded what is the order of prerequisites in $^ and, more important, > what is $<? Does it depend on the order of rules in the Makefile(s)? On the > type of rules (pattern, static pattern, explicit...)? On which rule has a > recipe? Is it deterministic? etc. > > I did some tests and came up with the following algorithm for $^ and $< > computation: > > 0. When the list of prerequisites of a rule is added to $^, the order is > preserved. > > 1. Initialize $^ with the list of prerequisites of the rule with a recipe, > implicit or not. > > 2. Consider all other applicable explicit or static pattern rules, in their > order of appearance in the Makefile(s), and for each of them append its list > of prerequisites to $^. > > 3. Ignore all other implicit rules (which seems to contradict 4.11). > > 4. Remove duplicates from $^, keeping only the first occurrence. > > 5. Set $< to the first prerequisite in $^. > > Can someone confirm? > > Renaud. >
