# COMPILE_OPTIONS

List of options to pass to the compiler.

This property holds a semicolon-separated list of options specified so far for its target. Use the `target_compile_options()` command to append more options. The options will be added after after flags in the `CMAKE_<LANG>_FLAGS` and `CMAKE_<LANG>_FLAGS_<CONFIG>` variables, but before those propagated from dependencies by the `INTERFACE_COMPILE_OPTIONS` property.

This property is initialized by the `COMPILE_OPTIONS` directory property when a target is created, and is used by the generators to set the options for the compiler.

Contents of `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.

## Option De-duplication

The final set of options used for a target is constructed by accumulating options from the current target and the usage requirements of its dependencies. The set of options is de-duplicated to avoid repetition.

New in version 3.12: While beneficial for individual options, the de-duplication step can break up option groups. For example, `-option A -option B` becomes `-option 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:-option A" "SHELL:-option B"` becomes `-option A -option B`.