# target_compile_options

Add compile options to a target.

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

Specify compile options to use when compiling a given target. The named `<target>` must have been created by a command such as `add_executable()` or `add_library()` and must not be an ALIAS target.

If `BEFORE` is specified, the content will be prepended to the property instead of being appended.

This command can be used to add any options, but alternative commands exist to add preprocessor definitions (`target_compile_definitions()` and `add_compile_definitions()`) or include directories (`target_include_directories()` and `include_directories()`). See documentation of the `directory` and `target` `COMPILE_OPTIONS` properties.

The `INTERFACE`, `PUBLIC` and `PRIVATE` keywords are required to specify the scope of the following arguments. `PRIVATE` and `PUBLIC` items will populate the `COMPILE_OPTIONS` property of `<target>`. `PUBLIC` and `INTERFACE` items will populate the `INTERFACE_COMPILE_OPTIONS` property of `<target>`. (IMPORTED targets only support `INTERFACE` items.) The following arguments specify compile options. Repeated calls for the same `<target>` append items in the order called.

Arguments to `target_compile_options` may use “generator expressions” with the syntax `$<...>`. See the `cmake-generator-expressions(7)` manual for available expressions. See the `cmake-buildsystem(7)` manual for more on defining buildsystem properties.

The final set of compile options used for a target is constructed by accumulating options from the current target and the usage requirements of it dependencies. The set of options is de-duplicated to avoid repetition. While beneficial for individual options, the de-duplication step can break up option groups. For example, `-D A -D B` becomes `-D A B`. One may specify a group of options using shell-like quoting along with a `SHELL:` prefix. The `SHELL:` prefix is dropped and the rest of the option string is parsed using the `separate_arguments()` `UNIX_COMMAND` mode. For example, `"SHELL:-D A" "SHELL:-D B"` becomes `-D A -D B`.