Re: Python recompile

On 07/03/2025 21:26, Lawrence D'Oliveiro wrote:
> On Thu, 6 Mar 2025 19:21:45 -0000 (UTC), Waldek Hebisch wrote:
> 
>> Per platform Makefile-s do not scale when one wants to support multiple
>> system and multiple configurations (there is exponential growth of
>> possible combinations).  And even of single configuration for supposedly
>> single system like Linux there are troubles.
>> In one project there was someting like 20 Makefile.linux_x files where x
>> represented one Linux flavour.  Yet regularly somebody would come and
>> say: "build fails on my Linux x.y.z".  If enough information was
>> provided new Makefile was added, or possibly some similar Makefile was
>> modified to cover more cases.
> 
> Can you offer more details on the project in question? I ask because
> there are things that can be done in GNU Makefiles to deal more
> dynamically with environmental differences in some simpler cases,
> without resorting to a full-on meta-build system like Autotools or
> CMake, and perhaps the maintainers of this project aren’t aware of
> that.
> 
> Here’s a simple example, building an extension module for Python:
> 
>      CFLAGS=-g $(shell python3-config --includes) -fPIC -Wall -Wno-switch -Wno-parentheses
> 
>      gxscript_lexer.so : gxscript_lexer.o
>          $(CC) $^ $(shell python3-config --ldflags) -shared -o $@
> 
>      gxscript_lexer.o : gxscript_lexer.c
> 
>      clean :
>          rm -f gxscript_lexer.so gxscript_lexer.o
>          rm -rf __pycache__
> 
>      .PHONY : clean
> 
> Note how it uses the “python3-config” command to figure out the right
> flags (including file/directory locations) for compilation and
> linking. So it doesn’t have to know that the libraries are in /usr/lib
> on one system, and /usr/local/lib on another.

So how does 'python3-config' know where this stuff is?