Custom Target that compiles into a subdirectory

[tmayoff]

I'm trying to compile some custom sources from .idl that compiles some files in the current build dir, as well as a subdirectory. This isn't possible with the custom_target custom_target keyword argument "output" Output 'AnyTypeCode/@BASENAME@A.h' must not contain a path segment. Is there a way to accomplish this properly?

Example of what I'm talking about

/
├── build <-- Generated
│   ├── AnyTypeCode
│   │   ├── GIOPA.h
│   │   └── GIOPA.cpp
│   ├── GIOPC.h
│   └── GIOPC.cpp
└── src <-- Original
    └── GIOP.pidl 

[eli-schwartz]

This is the stated purpose of generator(...).process(...): https://mesonbuild.com/Reference-manual_returned_generator.html#generatorprocess

Using the preserve_path_from: meson.current_source_dir() kwarg, all the generated headers (generated into the executable/library's private dir) will preserve the path structure.

[eli-schwartz]

Oh hmm, my understanding was that there's a common case of generated headers, in which you have 'foo/bar.gen', 'foo/bar/baz.gen' and you want to generate 'foo/bar.h', 'foo/bar.cpp', 'foo/bar/baz.h', 'foo/bar/baz.cpp'. This much plays nicely with preserve_path_from.

[tmayoff]

Oh yeah sorry my original question was poorly explained, do you know if this is possible to do simply?

[mitchgrout]

Bumping this; I have a similar need to generate source/headers from .proto files while maintaining a preserved folder structure, but the key problem is that generator.process() produces a target that acts differently from a standard custom_target, so if the generated headers get used in multiple build targets, the headers will be generated multiple times.

Are there any alternatives to this?

[mitchgrout]

What does the "no path segments allowed" check aim to mitigate? I'm wanting to create a custom packaging around something like https://protobuf.dev/reference/protobuf/google.protobuf/ which will internally contain directives like import "google.protobuf.[module]", so it is convenient for me to declare something like...

custom_target(
  input: fs.copyfile('google/protobuf/api.proto'),
  output: ['google/protobuf/api.pb.h', 'google/protobuf/api.pb.cc'],
  command: ['protoc', '--cpp_out=.', '@INPUT@'],
)

AFAIK custom_target should not assume it is in a particular directory, but I don't think there's many alternatives to this?

[eli-schwartz]

See #2320