Re: Built sources always regenerated

[Braden McDaniel]

On Sun, 2006-01-01 at 15:41 -0700, Tom Tromey wrote:
> >>>>> "Braden" == Braden McDaniel <address@hidden> writes:
> 
> Braden> Forget about BUILT_SOURCES and *_DEPENDENCIES. The sources I'm 
> building
> Braden> get #include'd by browser.cpp. As such, checking of browser.cpp's
> Braden> dependencies should cause them to get (re)generated, right?
> 
> Braden> But it doesn't. If I remove BUILT_SOURCES, the files don't get
> Braden> generated before browser.cpp gets compiled. Why not?
> 
> Automake dependency tracking information is computed as a side effect
> of compilation.  So, the first time things are compiled, it has no way
> of knowing about dependencies on generated files.

Yeah... I did some more thorough looking into how automake does its
thing and discovered this.

> BUILT_SOURCES is a hack to get around this.  It basically inserts a
> 'make $(BUILT_SOURCES)' before targets like 'all'.  (It would be nice
> to have per-{executable,library} BUILT_SOURCES...)
> 
> I didn't look into this too deeply but I would guess that it is more
> make-related than automake-related.  You can add rules to the
> Makefile.am to help with debugging, eg:
> 
> hack:
>         $(MAKE) $(BUILT_SOURCES)
> 
> Then in theory 'make hack' should reproduce the problem you're seeing.

And it does.

> If that doesn't happen then something weird and perhaps
> automake-related is going on.  If it does happen, you can try plain
> old Makefile debugging with 'make -d'.

<banging head against desk>

The problem is that antlr doesn't seem to modify the timestamp when it
regenerates files.

Solved by touching the generated files immediately after antlr runs.

<sigh>

Thanks for your help, gentlemen.

-- 
Braden McDaniel                           e-mail: <address@hidden>
<http://endoframe.com>                    Jabber: <address@hidden>