Problem using -R in MAKEFLAGS

Hi John,

I tried using ".SUFFIXES:".
Its a lot better but it still doesn't stop all of the built
in rules.

For the simple makefile:
.SUFFIXES:   

%.exe : %.c
    gcc -o $(F) $<
 
I still get:
  Considering target file `helloworld.c'.
   Looking for an implicit rule for `helloworld.c'.
   Trying pattern rule with stem `helloworld'.
   Trying implicit prerequisite `helloworld.w'.
   Trying pattern rule with stem `helloworld.c'.
   Trying implicit prerequisite `helloworld.c,v'.
   Trying pattern rule with stem `helloworld.c'.
   Trying implicit prerequisite `RCS/helloworld.c,v'.
   Trying pattern rule with stem `helloworld.c'.
   Trying implicit prerequisite `RCS/helloworld.c'.
   Trying pattern rule with stem `helloworld.c'.
   Trying implicit prerequisite `s.helloworld.c'.
   Trying pattern rule with stem `helloworld.c'.
   Trying implicit prerequisite `SCCS/s.helloworld.c'.
   Trying pattern rule with stem `helloworld'.
   Trying implicit prerequisite `helloworld.w'.
   Looking for a rule with intermediate file `helloworld.w'.
    Avoiding implicit rule recursion.
    Trying pattern rule with stem `helloworld.w'.
    Trying implicit prerequisite `helloworld.w,v'.
    Trying pattern rule with stem `helloworld.w'.
    Trying implicit prerequisite `RCS/helloworld.w,v'.
    Trying pattern rule with stem `helloworld.w'.
    Trying implicit prerequisite `RCS/helloworld.w'.
    Trying pattern rule with stem `helloworld.w'.
    Trying implicit prerequisite `s.helloworld.w'.
    Trying pattern rule with stem `helloworld.w'.
    Trying implicit prerequisite `SCCS/s.helloworld.w'.
   No implicit rule found for `helloworld.c'.
   Finished prerequisites of target file `helloworld.c'.
  No need to remake target `helloworld.c'.

Regards

Colm A

John Graham-Cumming wrote:
> Philip Guenther wrote:
>> You can't affect how make processes a makefile by
setting MAKEFLAGS in
>> the makefile itself.  Currently, make sets all the
built-in variables
>> and rules before parsing the makefile, and that can
be tested by the
>> makefile itself, so changing it would create all
sorts of problems.
>
> That's not actually totally true.  Page 50 of the GNU
Make manual 
> states: 'You can also set MAKEFLAGS in a makefile, to
specify 
> additional flags that should be in effect for that
makefile.'
>
> For example,
>
>     MAKEFLAGS += -n
>
>     .PHONY: all
>     all:
>         echo Doing all
>
> will print 'echo Doing all' because the -n is in effect
for that 
> Makefile.  Unfortunately, as you do state, there are
some flags that 
> will not work when MAKEFLAGS is set inside a Makefile. 
The source of 
> GNU Make shows that MAKEFLAGS is actually parsed twice:
once before 
> handling the Makefile and once after:
>
>   /* Decode switches again, in case the variables were
set by the 
> makefile.  */
>   decode_env_switches (STRING_SIZE_TUPLE
("MAKEFLAGS"));
>
> The flag you want to set for no built in rules is -r
(note that the 
> original message errorneously talked about -R which is
for built in 
> variables although it does force -r).  This translates
to the 
> no_builtin_rules_flag variable in GNU Make's source.
>
> Unfortunately, this flag is used to control the setting
up of the 
> built in rules BEFORE the Makefiles are parsed (as you
state) and 
> hence you can't add -r to MAKEFLAGS in a Makefile and
have it affect 
> that Makefile.  This is done so that new rules in the
Makefile can 
> override the default rules as necessary.
>
> Most of the command-line switches will work if
specified in MAKEFLAGS 
> in the Makefile and affect that Makefile (you can try
out silly 
> examples like -v and -p to see the effect).
>
> Now, to actually solve your problem (disabling default
rules in a 
> Makefile), there's a simple technique: you clear the
default suffix 
> list for built-in rules.  This will prevent any of the
built-in rules 
> from being searched and you can go ahead and define
your own pattern 
> rules.
>
> So simply write:
>
>     .SUFFIXES:
>
> in the Makefile where you want to disable built-in
rules.  This won't 
> kill the built-in variables, but they are probably less
of a worry.
>
> John.

-- 
------------------------------------------------------------
---------
 Colm Aengus Murphy,                Tel       : +353 1
2911000
 Senior Hardware Design Engineer,   Direct Tel: +353 1
2911373
 Silicon & Software Systems,        Fax       : +353 1
2911001
 South County Business Park,
 Leopardstown,                      E-mail: colm.murphys3group.com
 Dublin 18.                         WWW   : www.s3group.com
 Ireland
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