make .SECONDEXPANSION recipe execute twice

Question

Using GNU make, I am trying to solve a problem similar to make recipe execute twice — that is, to have a Makefile recipe run twice. In my case, however, the recipe is run under the .SECONDEXPANSION target, and the two different runs will be called with different parameters to generate different versions of the output file from the same input file. That is, with input file foo, this example Makefile should be callable via make foo.pdf or make foo.expanded.pdf to build one .pdf file, or make all to build both .pdf files:

.PHONY: all

all: foo.pdf foo.expanded.pdf

.SECONDEXPANSION:
%.expanded.pdf %.pdf: %
    @echo building $(basename $@)

Of the two solutions given in that answer, the first is unsuitable because it always runs the rule twice; I want it run twice when the user asks for it.

The second solution posted there is conceptually what I am looking for and have implemented in the above example Makefile, with only the small problem that it doesn't work: although the all target lists both .pdf files as dependencies, only one is built when make all is run.

Is there a way to tell GNU make to build two different files using the same rule under a .SECONDEXPANSION?

EDIT: Clarified in problem description that the same input file is used to build both versions of the output file, and modified sample Makefile to include this dependency.

EDIT: I would like a solution as scalable as possible; that is, it should work if the input filename contains dots, specifying additional output file foo.reduced.pdf should require only adjusting the targets and recipe as appropriate, etc. This limits performing string surgery that relies on the filenames appearing exactly as given in this narrow example (e.g., changing the rule to %.pdf: $$(firstword $$(subst ., ,$$*)) fails if the input file could be either foo or foo.bar).

Answer 1

Your problem has nothing to do with .SECONDEXPANSION. You can just drop that and the problem will be the same.

Your problem is that you are using a pattern rule with multiple target patterns, and expecting that it works similar to an explicit rule with multiple targets. But it does not (and in fact you cannot have a rule with both pattern and explicit targets).

For a pattern rule with multiple target patterns, Make matches the same pattern to all the %, including multiple times in the targets, and then assumes that it just has to execute the recipe with that pattern once, and it will make all the matched targets.

In your case the best way is to use multiple rules (I changed your recipe because using echo as a Make recipe is a bad idea):

.PHONY: all
all: foo.expanded.pdf foo.pdf 

RECIPE = touch $@

%.expanded.pdf:
    $(RECIPE)

%.pdf:
    $(RECIPE)

Answer 2

You are probably looking for Pattern-specific Variable Values. Let's assume your recipe depends on a make variable named BUILDFLAGS that takes value normal by default and special for the "expanded" targets. Then this Makefile:

BUILDER    := builder
BUILDFLAGS := normal

.PHONY: all

all: foo.pdf foo.expanded.pdf

%.expanded.pdf: BUILDFLAGS := special

%.pdf:
    $(BUILDER) $(BUILDFLAGS) $@

should do about what you want with the same rule for all targets, plus one pattern-specific variable value declaration. Replace builder, normal and special with what makes sense in your case. Demo:

$ make foo.pdf
builder normal foo.pdf
$ make foo.expanded.pdf
builder special foo.expanded.pdf
$ make
builder normal foo.pdf
builder special foo.expanded.pdf