name: shared_module
returns: build_tgt
since: 0.37.0
description: |
  Builds a shared module with the given sources.

  This is useful for building modules that will be `dlopen()`ed and
  hence may contain undefined symbols that will be provided by the
  library that is loading it.

  If you want the shared module to be able to refer to functions and
  variables defined in the [[executable]] it is loaded by,
  you will need to set the `export_dynamic` argument of the executable to
  `true`.

notes:
 - |
   *Linking to a shared module on platforms other than Android is deprecated, and will be an error
   in the future*.
   It was previously allowed because it was the only way to have a shared-library-like target that
   contained references to undefined symbols. However, since 0.40.0, the `override_options:`
   [[build_target]] keyword argument can be used to create such a [[shared_library]] by passing
   `override_options: 'b_lundef=false'`. Shared modules have other characteristics that make
   them incompatible with linking, such as a lack of SONAME.
   On macOS and iOS, linking to shared modules is disallowed by the linker, so we disallow it at
   configure time.
   On Android, if a shared module `foo` uses symbols from another shared module `bar`, `foo` must
   also be linked to `bar`. Hence, linking one shared module to another will always be allowed when
   building for Android.

posargs_inherit: _build_target_base
varargs_inherit: _build_target_base
kwargs_inherit: _build_target_base

kwargs:
  vs_module_defs:
    type: str | file | custom_tgt | custom_idx
    since: 0.52.0
    description: |
      Specify a Microsoft module definition file for controlling symbol exports,
      etc., on platforms where that is possible (e.g. Windows).

  rust_abi:
    type: str
    since: 1.3.0
    description: |
      Set the specific ABI to compile (when compiling rust).
      - 'rust' (default): Create a "dylib" crate.
      - 'c': Create a "cdylib" crate.