Re: outputting which dependencies triggered a target action

[John Graham-Cumming]

Noel Yap wrote:
> Is there an option less verbose than --debug that outputs which 
> dependencies triggered a target action?

You can hack it like this:

    OLD_SHELL := $(SHELL)
    SHELL = $(warning Building $@ $(if $?,because $? newer,because $@ 
is missing))$(OLD_SHELL)

Then you'll get a lot of warnings.  If you filter on just those that 
mention a Makefile name and line number you'll see something like this:

    shell3.mak:8: Building foo because foo is missing
    shell3.mak:8: Building bar because bar is missing
    shell3.mak:5: Building all because foo bar newer

for a Makefile like that:

    all: foo bar
        @echo Make all

    foo bar:
        @echo Make $@

I am planning to write an article for CM Crossroads about tricks with 
redefining SHELL for the October CM Basics.

John.
--
John Graham-Cumming
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