[build2] how to compile different executables with different flags

[Boris Kolpackov]

Alberto Sartori <alberto.sartori at sissa.it> writes:

> I would like to use build2 to build some executables for a course of
> C++. I have several source files (each one with a main) and I would like
> to compile a couple of them with a couple of more flags with respect to
> the others. How can I do that?
> 
> $ cat build/root.build
> cxx.std = 14
> 
> using cxx
> 
> cxx{*}: extension = cc
> 
> cxx.coptions=-O3
> cxx.poptions=-Wall -Wextra
> 
> $ cat buildfile
> 
> src = 01_enum.cc	\
> 02_scoped_enum.cc	\
> 03_namespace.cc		\
> 04_why_scoped.cc	\
> 05_struct_class.cc	\
> 06_constructor_destructor.cc	\
> 07_template_class.cc
> 
> for s : $src
> {
>   n = $name($s)
>   ./: exe{$n".x"} : cxx{$n}
> }

You can use target-specific variables for that, for example:

obj{01_enum}: cxx.coptions += -Wno-uninitialized

You can also list several targets at once:

obj{01_enum 02_scoped_enum}: cxx.coptions += -Wno-uninitialized

If you want link options instead of compile, then you would use
the executable target:

exe{01_enum.x}:
{
  cxx.loptions += -static
  cxx.libs += -lpthread
}

BTW, that .x extension for the executable target makes your project
non-portable (since you've specified your own extension, build2 will
do as it's told and use this extension even on Windows).