[bug #56732] VPATH doesn't work with pattern rules

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?56732>

                 Summary: VPATH doesn't work with pattern rules
                 Project: make
            Submitted by: None
            Submitted on: Thu 08 Aug 2019 11:26:35 AM UTC
                Severity: 3 - Normal
              Item Group: Bug
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: 4.2.1
        Operating System: POSIX-Based
           Fixed Release: None
           Triage Status: None

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Details:

VPATH doesn't work with pattern rules, at least when using link libraries. I
can see nothing in the manual to suggest it shouldn't. Here's a reduced test
case.

Steps to reproduce:

In an empty directory, create the following dirs/files:

mkdir libs
touch libs/libAbc.a
mkdir input
touch input/example.in
touch input/example2.in
mkdir output


Create a Makefile with the following contents:


VPATH = libs

#irrelevant_recipe : -lAbc
#       echo "This recipe is never run"

output/% : input/%.in -lAbc
        @echo "Running recipe to build $@ from $<"



Run this command:

make output/example


Actual behaviour:


> make output/example
make: *** No rule to make target `output/example'.  Stop.


Expected behaviour:


> make output/example
Running recipe to build output/example from input/example.in


Note: Uncommenting the "irrelevant" recipe causes the pattern rule to work in
the above case. However, this workaround only works for one item - if you try
to build example and example2 at the same time, it still fails to build
whichever one comes second. But either can be built individually:


> make output/example
Running recipe to build output/example from input/example.in
> make output/example2
Running recipe to build output/example2 from input/example2.in
> make output/example output/example2
Running recipe to build output/example from input/example.in
make: *** No rule to make target `output/example2'.  Stop.


This makes it not useful as a workaround, as really the point of pattern rules
is to build multiple items using the same rule.





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