Re: Finding second route through rules

[Steven Simpson]

Hi again!

On 01/02/16 21:29, Luke Shumaker wrote:
> Here is an "improved" makefile that I think demonstrates the situation
> more clearly.
>
>         default: a.foo
>         
>         %.foo: %.correct
>                 @echo $@ from $<
>         
>         %.foo: %.mislead
>                 @echo $@ from $<
>         
>         %.correct: %.correct_src
>                 @echo $@ from $<
>         
>         %.mislead: %.mislead_src
>                 @echo $@ from $<
>         
>         a.correct_src:
>                 @echo touch $@
>         
>         # Note that there is no rule to make a.mislead_src
>         
>         # If the misleading_target line is commented out, 'default' succeeds:
>         # > a.correct from correct_src
>         # > a.foo from a.correct
>         # If the line isn't commented out, 'default' fails:
>         # > make: *** No rule to make target 'a.mislead', needed by 'a.foo'.  
> Stop.
>         misleading_target: a.mislead

> I had to work through this several times to convince myself that this
> wasn't a simple misunderstanding of trying to apply ≤3.81 pattern
> rules in a post-3.82 world.
> Without looking at the source, this feels a lot like the
> .DELETE_ON_ERROR: bug that was in either 3.81 or 3.82 (I can't
> recall which).

A little more info which might be pertinent...  In moving to a newer 
Kubuntu (14.04 to 16.04), I've implicitly switched from GNU Make 3.81 to 
4.1.  Having hit what is likely the same problem, I had to try out some 
other versions.  Both the code I'm working on now and Luke's test above 
manifest a problem in 3.82, 4.1 and 4.2.1, but not in 3.81.

Cheers,

Steven