Function LLVMRustCoverageWriteFunctionMappingsToBuffer 

pub(crate) unsafe extern "C" fn LLVMRustCoverageWriteFunctionMappingsToBuffer(
    VirtualFileMappingIDs: *const c_uint,
    NumVirtualFileMappingIDs: size_t,
    Expressions: *const CounterExpression,
    NumExpressions: size_t,
    CodeRegions: *const CodeRegion,
    NumCodeRegions: size_t,
    ExpansionRegions: *const ExpansionRegion,
    NumExpansionRegions: size_t,
    BranchRegions: *const BranchRegion,
    NumBranchRegions: size_t,
    BufferOut: &RustString,
)