Re: Bug in pattern rule parsing: how to handle?

[Philip Guenther]

On Wed, Oct 29, 2008 at 2:12 PM, Sam Ravnborg <address@hidden> wrote:
> On Sun, Oct 26, 2008 at 07:12:53PM -0400, Paul Smith wrote:
...
>>         Makefile:442: *** mixed implicit and normal rules.  Stop.
>>
>>         config %config: scripts_basic outputmakefile FORCE
>>                 $(Q)mkdir -p include/linux include/config
>>                 $(Q)$(MAKE) $(build)=scripts/kconfig $@
>
> Here I try to catch the following:
>
> make config
> make menuconfig
> make xconfig
> make foobarconfig
>
> I must admit I cannot see the problem with mixing implicit and normal
> rules in the above. But I gues this is my simple use of it.

I see at least two ways in which it's confusing:
1) what prerequisites does "foo" have with this rule:
    foo %.c: %.c.real
        @: cp $< $@

2) rules with multiple pattern targets have special meaning to make:
       Pattern rules may have more than one target.  Unlike normal rules,
       this does not act as many different rules with the same prerequisites
       and commands.  If a pattern rule has multiple targets, `make' knows that
       the rule's commands are responsible for making all of the targets.  <...>
    I.e., this rule:
    %.a %.b:
        ${commands}
    says that building "bar.a" will also build "bar.b", and
    building "quux.a" will also build "quux.b".  With this rule:
    foo %.a %.b:
        ${commands}
    should make assume that building "bar.a" will also build "bar.b"
*and* "foo"?
    How about this rule:
    foo blip %.a %.b:
        ${commands}
    Will building "bar.a" also build "bar.b", "foo", and "blip"?
    How about this one:
    foo blip %.a:
        ${commands}
    ...whoops...


> Do you have any god suggestion how to rewrite this?

Option 1: if "make config" is really the same as "make fooconfig",
then actually set that equivalence in the makefile with something
like:

config: fooconfig
%config: scripts_basic outputmakefile FORCE
        $(Q)mkdir -p include/linux include/config
        $(Q)$(MAKE) $(build)=scripts/kconfig $@



Option 2: if the list of config types is basically static, then just
list them explicitly:

CONFIG_TARGETS = config menuconfig xconfig foobarconfig
${CONFIG_TARGETS}: scripts_basic outputmakefile FORCE
        $(Q)mkdir -p include/linux include/config
        $(Q)$(MAKE) $(build)=scripts/kconfig $@


Option 3: if the list of config targets really does change regularly
or needs to be open-ended, then I would go with

CONFIG_DEP = scripts_basic outputmakefile FORCE
define CONFIG_COMMANDS
        $(Q)mkdir -p include/linux include/config
        $(Q)$(MAKE) $(build)=scripts/kconfig $@
endef

# normal and pattern targets are immiscible in a single rule
config: ${CONFIG_DEP}; ${CONFIG_COMMANDS}
%config: ${CONFIG_DEP}; ${CONFIG_COMMANDS}


(The version using $(eval) and $(foreach) is just icky looking in my mind)


Philip Guenther