Re: confused about double-colon "terminal" rules

[John Graham-Cumming]

Robert P. J. Day wrote:
> "One choice is to mark the match-anything rule as terminal by defining
> it with a double colon. When a rule is terminal, it does not apply
> unless its prerequisites actually exist. Prerequisites that could be
> made with other implicit rules are not good enough. In other words, no
> further chaining is allowed beyond a terminal rule."
>
>   so i have this trivial makefile:
>
> t1::    hi
>         @echo hi there
>
> and in that directory, i have the source file "hi.c".  now, the
> prerequisite of "hi" could clearly be built using the implicit pattern
> rule for compiling C files but, according to the above manual excerpt,
> a terminal rule should *absolutely* not consider other implicit rules.
>
> so ...
>
> $ make t1
> cc      hi.c    -o hi
> hi
> $
>
>   huh?  why was an implicit rule used to build that dependency?  how
> am i misreading this?

Firstly the section you are quoting refers to "match-anything rules". 
Those are rules whose LHS is '%:' or '%::".

Secondly the example you give is not for a pattern rule at all, but for 
a standard non-pattern rule.  All you've done is define a double colon rule.

The concept of a terminal rule is specifically related to pattern 
matching rules to prevent enormous searches.

John.
--
John Graham-Cumming
address@hidden

Home: http://www.jgc.org/
Blog: http://www.jgc.org/blog/

POPFile: http://getpopfile.org/
GNU Make Standard Library: http://gmsl.sf.net/
GNU Make Debugger: http://gmd.sf.net/
Fast, Parallel Builds: http://www.electric-cloud.com/

Sign up for my Spam and Anti-spam Newsletter
at http://www.jgc.org/