Hello,
I tried to use `wildcard` in place of doing `ls` and found some
limitation I did not know about.
I faced the issue that, even with deferred variables, the value of
`wildcard` was cached to the value it has on first evaluation and does
not reflect the last state of the filesystem.
Which makes adding `$(info $(VARIABLE_VALUE))` change the behavior.
In my case, if I do not want to change the original behavior, I need to
do twice `ls` to have the initial and the final state, as I cannot
before running, know the name of the target directory.
It is generated by `scan-build` that uses a dynamic name.
I could move it to a fixed name, but that would be working around
instead of understanding if there is a low level solution.
Also I did not find any reference in the documentation on the behavior
or any way to force re-evaluating `wildcard` and it took me a while to
understand what was happening. Maybe I looked in the wrong place and the
right link would also be a good answer.
### Testing procedure
I tested with make from `ubuntu bionic` and also on another machine
using `arch linux`, so more recent, but do not have the version number.
make --version
GNU Make 4.1
In the following test snippet [1], I would imagine that doing
make and make EVALUATE_WILDCARD=1 would both work
But when doing `make EVALUATE_WILDCARD=1` the last `test -f` uses the
value of the first time where `wildcard` was evaluated.
Any hint on how to force the evaluation again, or a way to do twice this
`ls` without relying on the shell is welcome.
I know I can just use a fixed name, or use the shell but that would be
working around before understanding :)
Thank you in advance.
Best regards,
Gaëtan
1:
# I am trying to use `wildcard` as a way to do `ls`.
#
#
# This simulate a local use case of `scan-build`.
#
# The final name '$(OUTDIR)/*/index.html' is not known in advance.
# It is generated by 'scan-build' so not predictable directory name.
#
# I tried to get the name using `wildcard` but if wildcard
# is used before, the initial value is returned.
#
# Try running 'make' and 'make EVALUATE_WILCARD=1'
OUTDIR = tmp
OUTPUT_FILE = $(addsuffix /index.html,$(wildcard $(OUTDIR)/*))
# Just be sure about the initial context
# One file in 'tmp/a/index.html'
$(shell rm -rf $(OUTDIR)/*)
$(shell mkdir -p $(OUTDIR)/a)
$(shell touch $(OUTDIR)/a/index.html)
ifneq (,$(EVALUATE_WILDCARD))
$(info Evaluate `wildcard` before creating the new file)
$(info OUTPUT_FILE=$(OUTPUT_FILE))
endif
.PHONY: all create clean
all: create
test -f $(OUTPUT_FILE)
create: clean
mkdir -p $(OUTDIR)/b/
touch $(OUTDIR)/b/index.html
clean:
rm -rf $(OUTDIR)/
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