# target_sources

New in version 3.1.

Add sources to a target.

    target_sources(<target>
      <INTERFACE|PUBLIC|PRIVATE> [items1...]
      [<INTERFACE|PUBLIC|PRIVATE> [items2...] ...])

Specifies sources to use when building a target and/or its dependents. The named `<target>` must have been created by a command such as `add_executable()` or `add_library()` or `add_custom_target()` and must not be an ALIAS target. The `<items>` may use `generator expressions`.

New in version 3.20: `<target>` can be a custom target.

The `INTERFACE`, `PUBLIC` and `PRIVATE` keywords are required to specify the scope of the source file paths (`<items>`) that follow them. `PRIVATE` and `PUBLIC` items will populate the `SOURCES` property of `<target>`, which are used when building the target itself. `PUBLIC` and `INTERFACE` items will populate the `INTERFACE_SOURCES` property of `<target>`, which are used when building dependents. A target created by `add_custom_target()` can only have `PRIVATE` scope.

Repeated calls for the same `<target>` append items in the order called.

New in version 3.3: Allow exporting targets with `INTERFACE_SOURCES`.

New in version 3.11: Allow setting `INTERFACE` items on IMPORTED targets.

Changed in version 3.13: Relative source file paths are interpreted as being relative to the current source directory (i.e. `CMAKE_CURRENT_SOURCE_DIR`). See policy `CMP0076`.

A path that begins with a generator expression is left unmodified. When a target's `SOURCE_DIR` property differs from `CMAKE_CURRENT_SOURCE_DIR`, use absolute paths in generator expressions to ensure the sources are correctly assigned to the target.

    # WRONG: starts with generator expression, but relative path used
    target_sources(MyTarget PRIVATE "$<$<CONFIG:Debug>:dbgsrc.cpp>")

    # CORRECT: absolute path used inside the generator expression
    target_sources(MyTarget PRIVATE "$<$<CONFIG:Debug>:${CMAKE_CURRENT_SOURCE_DIR}/dbgsrc.cpp>")

See the `cmake-buildsystem(7)` manual for more on defining buildsystem properties.

## File Sets

New in version 3.23.

    target_sources(<target>
      [<INTERFACE|PUBLIC|PRIVATE>
       [FILE_SET <set> [TYPE <type>] [BASE_DIRS <dirs>...] [FILES <files>...]]...
      ]...)

Adds a file set to a target, or adds files to an existing file set. Targets have zero or more named file sets. Each file set has a name, a type, a scope of `INTERFACE`, `PUBLIC`, or `PRIVATE`, one or more base directories, and files within those directories. The acceptable types include:

`HEADERS`

> Sources intended to be used via a language's `#include` mechanism.

`CXX_MODULES`

> Note

> Experimental. Gated by `CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API`

> Sources which contain C++ interface module or partition units (i.e., those using the `export` keyword). This file set type may not have an `INTERFACE` scope except on `IMPORTED` targets.

`CXX_MODULE_HEADER_UNITS`

> Note

> Experimental. Gated by `CMAKE_EXPERIMENTAL_CXX_MODULE_CMAKE_API`

> C++ header sources which may be imported by other C++ source code. This file set type may not have an `INTERFACE` scope except on `IMPORTED` targets.

The optional default file sets are named after their type. The target may not be a custom target or `FRAMEWORK` target.

Files in a `PRIVATE` or `PUBLIC` file set are marked as source files for the purposes of IDE integration. Additionally, files in `HEADERS` file sets have their `HEADER_FILE_ONLY` property set to `TRUE`. Files in an `INTERFACE` or `PUBLIC` file set can be installed with the `install(TARGETS)` command, and exported with the `install(EXPORT)` and `export()` commands.

Each `target_sources(FILE_SET)` entry starts with `INTERFACE`, `PUBLIC`, or `PRIVATE` and accepts the following arguments:

`FILE_SET <set>`

> The name of the file set to create or add to. It must contain only letters, numbers and underscores. Names starting with a capital letter are reserved for built-in file sets predefined by CMake. The only predefined set names are those matching the acceptable types. All other set names must not start with a capital letter or underscore.

`TYPE <type>`

> Every file set is associated with a particular type of file. Only types specified above may be used and it is an error to specify anything else. As a special case, if the name of the file set is one of the types, the type does not need to be specified and the `TYPE <type>` arguments can be omitted. For all other file set names, `TYPE` is required.

`BASE_DIRS <dirs>...`

> An optional list of base directories of the file set. Any relative path is treated as relative to the current source directory (i.e. `CMAKE_CURRENT_SOURCE_DIR`). If no `BASE_DIRS` are specified when the file set is first created, the value of `CMAKE_CURRENT_SOURCE_DIR` is added. This argument supports `generator expressions`.

> No two base directories for a file set may be sub-directories of each other. This requirement must be met across all base directories added to a file set, not just those within a single call to `target_sources()`.

`FILES <files>...`

> An optional list of files to add to the file set. Each file must be in one of the base directories, or a subdirectory of one of the base directories. This argument supports `generator expressions`.

> If relative paths are specified, they are considered relative to `CMAKE_CURRENT_SOURCE_DIR` at the time `target_sources()` is called. An exception to this is a path starting with `$<`. Such paths are treated as relative to the target's source directory after evaluation of generator expressions.

The following target properties are set by `target_sources(FILE_SET)`, but they should not generally be manipulated directly:

For file sets of type `HEADERS`:

- `HEADER_SETS`

- `INTERFACE_HEADER_SETS`

- `HEADER_SET`

- `HEADER_SET_<NAME>`

- `HEADER_DIRS`

- `HEADER_DIRS_<NAME>`

For file sets of type `CXX_MODULES`:

- `CXX_MODULE_SETS`

- `INTERFACE_CXX_MODULE_SETS`

- `CXX_MODULE_SET`

- `CXX_MODULE_SET_<NAME>`

- `CXX_MODULE_DIRS`

- `CXX_MODULE_DIRS_<NAME>`

For file sets of type `CXX_MODULE_HEADER_UNITS`:

- `CXX_MODULE_HEADER_UNIT_SETS`

- `INTERFACE_CXX_MODULE_HEADER_UNIT_SETS`

- `CXX_MODULE_HEADER_UNIT_SET`

- `CXX_MODULE_HEADER_UNIT_SET_<NAME>`

- `CXX_MODULE_HEADER_UNIT_DIRS`

- `CXX_MODULE_HEADER_UNIT_DIRS_<NAME>`

Target properties related to include directories are also modified by `target_sources(FILE_SET)` as follows:

`INCLUDE_DIRECTORIES`

> If the `TYPE` is `HEADERS` or `CXX_MODULE_HEADER_UNITS`, and the scope of the file set is `PRIVATE` or `PUBLIC`, all of the `BASE_DIRS` of the file set are wrapped in `$<BUILD_INTERFACE>` and appended to this property.

`INTERFACE_INCLUDE_DIRECTORIES`

> If the `TYPE` is `HEADERS` or `CXX_MODULE_HEADER_UNITS`, and the scope of the file set is `INTERFACE` or `PUBLIC`, all of the `BASE_DIRS` of the file set are wrapped in `$<BUILD_INTERFACE>` and appended to this property.