CODEWITHSUNDEEP
makefile
Clydog
Clydog

Reputation: 108

Make fails to notice changes

I have an issue with Make failing to rebuild a target because it doesn't believe that anything has changed. I've distilled the issue down to the following two Makefiles:

1) Makefile

.DEFAULT_GOAL := all

%:
    @echo "Catch all for $@"
    @make -sf common.mk $@

2) common.mk

.PHONY: all clean

all:
    @make -s package
    @echo "Nothing to do for all"

package: ${shell find ./src -type f}
    @echo "The following files have changed... $?"
    @echo "Making 'package'"
    @touch package

clean:
    @echo "Cleaning 'package'"
    @rm -f package

With the above, you can reproduce the issue by:

$mkdir src
$touch src/test.c
$make

At this point, if you try and make again, it correctly determines that nothing has changed...

$make

But then, if you simulate a change and try to rebuild, it doesn't think anything has changed...

$touch src/test.c
$make

If I move the 'package' target from common.mk to Makefile, it works fine, so there is something it really doesn't like, but I'm really not sure what is going on.

Any ideas?

Upvotes: 0

Views: 120

Answers (1)

Beta
Beta

Reputation: 99094

Here:

all:
    @make -s package

In that call to Make, you don't specify which makefile to use, so Make looks for the defaults and finds a file named "Makefile". The new instance of Make attempts to rebuild package using the makefile Makefile, and finds this rule:

%:
    @echo "Catch all for $@"
    @make -sf common.mk $@

Note that this rule has no prerequisites, package has not been declared PHONY, and a file named "package" already exists. So Make[1] sees no reason to rebuild the file, and terminates, passing control back to its parent Make.

Upvotes: 1

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