RFC: customizing buildtype

[bruchar1]

I had an idea about an improvement for buildtype, and I'd like to get some feedback about it.

My idea would be to add a new function to meson.options file:

buildtype('name', debug: true, optimization: '1', ...)

where keywords would be any existing option (builtin, or user defined).

That function would allow three things:

• redefine existing buildtypes, but with different values for debug or optimization
• define new buildtypes for the project
• define default values for any option, for the specified buildtype.

For instance, one could define the default b_ndebug option per buildtype like this:

buildtype('release', b_ndebug: true)
buildtype('plain', b_ndebug: true)
buildtype('debugoptimized', b_ndebug: false)
...

Same for b_vscrt, or for any other option (builtin or user).

Having this would lessen the need for special option values like 'if-release' for b_ndebug, or 'from_buildtype' and 'static_from_buildtype' for b_vscrt, and would allow other options to depend on the buildtype, without special treatment.

The order of precedence would be:

• hardcoded default value
• meson.options file
• project default_options
• buildtype options
• machine files
• command line

What do you think of this?

[eli-schwartz]

redefine existing buildtypes, but with different values for debug or optimization

CMake allows redefining existing build types and it's an endless source of trouble. IMO this should never ever ever be allowed. If a built-in buildtype is irreparably broken for a given project, simply define a new build type and use that instead. Check for its use in meson.build and raise an error() if users use it.

[bruchar1]

You probably have more experience than me about this point... What I'm thinking about are things like: "I want a 'release' build with optimization: '2'", "I want a 'plain' build with/without debug info...", "I want a 'debugoptimized' build with "optimization: '3'".

Redefining those things could be convenient for interoperability with other tools, like using conan for fetching dependencies and generating machine file (like I do in my project).

On the other hand, I think my proposition would still be very usable (and useful) even if it disallows buildtype redefinition.