name: install_headers
returns: void
description: |
  Installs the specified header files from the source tree into the
  system header directory (usually `/{prefix}/include`) during the
  install step. This directory can be overridden by specifying it with
  the `install_dir` keyword argument. If you just want to install into a
  subdirectory of the system header directory, then use the `subdir`
  argument. As an example if this has the value `myproj` then the
  headers would be installed to `/{prefix}/include/myproj`.

example: |
  For example, this will install `common.h` and `kola.h` into
  `/{prefix}/include`:

  ```meson
  install_headers('common.h', 'proj/kola.h')
  ```

  This will install `common.h` and `kola.h` into `/{prefix}/include/myproj`:

  ```meson
  install_headers('common.h', 'proj/kola.h', subdir : 'myproj')
  ```

  This will install `common.h` and `kola.h` into `/{prefix}/cust/myproj`:

  ```meson
  install_headers('common.h', 'proj/kola.h', install_dir : 'cust', subdir : 'myproj')
  ```

varargs:
  name: file
  type: file | str
  description: Header files to install.

kwargs:
  install_dir:
    type: str
    description: Where to install to.

  subdir:
    type: str
    description: |
      Install to the `subdir` subdirectory of the default includedir.

      Incompatible with the `install_dir` kwarg.

  install_mode:
    type: list[str | int]
    since: 0.47.0
    description: |
      Specify the file mode in symbolic format
      and optionally the owner/uid and group/gid for the installed files.

      See the `install_mode` kwarg of [[install_data]] for more information.