bool SkSLToBackend(const SkSL::ShaderCaps *caps, bool(*toBackend)(SkSL::Program &, const SkSL::ShaderCaps *, std::string *), const char *backendLabel, const std::string &sksl, SkSL::ProgramKind programKind, const SkSL::ProgramSettings &settings, std::string *output, SkSL::ProgramInterface *outInterface, ShaderErrorHandler *errorHandler)