# [−][src]Function core::intrinsics::count_code_region

    #[lang = "count_code_region"]pub unsafe extern "rust-intrinsic" fn count_code_region(
        function_source_hash: u64,
        index: u32,
        file_name: &'static str,
        start_line: u32,
        start_col: u32,
        end_line: u32,
        end_col: u32
    )

🔬 This is a nightly-only experimental API. (`core_intrinsics`)

intrinsics are unlikely to ever be stabilized, instead they should be used through stabilized interfaces in the rest of the standard library

Internal placeholder for injecting code coverage counters when the "instrument-coverage" option is enabled. The source code region information is extracted prior to code generation, and added to the "coverage map", which is injected into the generated code as additional data. This intrinsic then triggers the generation of LLVM intrinsic call `instrprof.increment`, using the remaining args (`function_source_hash` and `index`).