Re: Make does not throw an error for target without a recipe?

[Patrick Donnelly]

Hi Paul,

On Thu, Jun 26, 2014 at 4:48 PM, Paul Smith <address@hidden> wrote:
>>  File 'foo' does not exist.
>>  Looking for an implicit rule for 'foo'.
>> [...]
>>  No implicit rule found for 'foo'.
>>   Considering target file '/etc/passwd'.
>>    Looking for an implicit rule for '/etc/passwd'.
>> [...]
>>    No implicit rule found for '/etc/passwd'.
>>    Finished prerequisites of target file '/etc/passwd'.
>>   No need to remake target '/etc/passwd'.
>>  Finished prerequisites of target file 'foo'.
>> Must remake target 'foo'.
>> Successfully remade target file 'foo'.
>> make: Nothing to be done for 'foo'.
>>
>> So the interesting thing here is that Make decides it needs to remake
>> `foo' but it doesn't do anything (based on strace output). Then it
>> decides it was successful?
>
> See:
> http://www.gnu.org/software/make/manual/html_node/Force-Targets.html

I read that part of the manual, my interpretation of

"If a rule has no prerequisites or recipe, and the target of the rule
is a nonexistent file, then make imagines this target to have been
updated whenever its rule is run."

only applies if a rule has no prerequisites AND no recipe, a special
case of FORCE or "empty" targets like a not-yet-written uninstall
target. I guess I'm confused by the wording there.

>> That doesn't make any sense... How do I get Make to fail if it can't
>> make the target?
>
> You have to give make a recipe to run.  Then if the recipe fails (exits
> with a non-zero error code), make will fail.

This is a little inconvenient when you're relying on implicit rules. e.g.

%.o: %.c
    cc -o $@ $<
%: %.o
    ld $@ $^

foo: bar.a

Even if foo.c is missing, Make still succeeds. This is actually what
I'm dealing with and I'd like a method of catching a mistake like a
missing .c file in the future.

-- 
Patrick Donnelly