Re: enhancement: better clarification of search side effects

[Alejandro Colomar]

Hi Peter,

On 6/1/23 21:42, Peter Radisson wrote:
> 
> 
> Am 01.06.23 um 03:39 schrieb Dmitry Goncharov:
>> On Wed, May 31, 2023 at 12:40 PM <Radisson97@web.de> wrote:
>>> today i had a strange problem with a long used makefile (GNU Make 4.3).
>>> It found a file called "all.sh" and did a "cat <all.sh >all".
>>
>> That's not a strange problem. That's the default make behavior.
>>
> 
> In the moment when you suddenly see that kind of problem is is strange,
> i did not remember imediately that .sh was a registered suffix.
> The list of predefined suffixes is in "Catalogue of Built-In Rules"
> not the first place to look, actually i used google to find it,
> searching sh in a document is ambitious.
> 
>>> I use makefile for a long time but that effect happend the first time to me.
>>> It would be helpful to improve the documentation that people will be aware
>>> that this can happen. The phony section has some hints this way, maybe this
>>> is a good example to show what happens if you do not use phony.
>>
>> What piece of documentation do you think is missing?
>> Did you see documentation on default suffix rules?
> 
> I read that years ago, i remembered when i saw the PHONY page, and
> confirmed with make -p.
I very much recommend casting the following spells, which protect you
from hidden magic stuff that make(1) does by default and I find very
confusing.

MAKEFLAGS += --no-builtin-rules
MAKEFLAGS += --no-builtin-variables
MAKEFLAGS += --warn-undefined-variables

Do that, and you'll rarely find surprises.

Cheers,
Alex

> 
> I use make a lot but only a subset and as seen sometimes i get a
> surprise. A beginner may be even more surprised (non of my coworkers
> spotted the problem).
> 
> IMHO there is a lack examples in the decumentation that are intentionaly
> wrong (or show unintended side effects), examples that demonstrate *why*
> someone sould do certain things (For now i will add more .PHONY in my
> makefiles).
> 
> hope that helps,
> 
>>
>> regards, Dmitry
>