format

    pub fn format(self: CallConv, w: *Writer) Writer.Error!void {
        switch (self) {
            default => {},
            .fastcc,
            .coldcc,
            .ghccc,
            .webkit_jscc,
            .anyregcc,
            .preserve_mostcc,
            .preserve_allcc,
            .swiftcc,
            .cxx_fast_tlscc,
            .tailcc,
            .cfguard_checkcc,
            .swifttailcc,
            .preserve_nonecc,
            .x86_stdcallcc,
            .x86_fastcallcc,
            .arm_apcscc,
            .arm_aapcscc,
            .arm_aapcs_vfpcc,
            .msp430_intrcc,
            .x86_thiscallcc,
            .ptx_kernel,
            .ptx_device,
            .spir_func,
            .spir_kernel,
            .intel_ocl_bicc,
            .x86_64_sysvcc,
            .win64cc,
            .x86_vectorcallcc,
            .hhvmcc,
            .hhvm_ccc,
            .x86_intrcc,
            .avr_intrcc,
            .avr_signalcc,
            .avr_builtincc,
            .amdgpu_vs,
            .amdgpu_gs,
            .amdgpu_ps,
            .amdgpu_cs,
            .amdgpu_kernel,
            .x86_regcallcc,
            .amdgpu_hs,
            .msp430_builtincc,
            .amdgpu_ls,
            .amdgpu_es,
            .aarch64_vector_pcs,
            .aarch64_sve_vector_pcs,
            .amdgpu_gfx,
            .m68k_intrcc,
            .aarch64_sme_preservemost_from_x0,
            .aarch64_sme_preservemost_from_x2,
            .m68k_rtdcc,
            .riscv_vectorcallcc,
            => try w.print(" {s}", .{@tagName(self)}),
            _ => try w.print(" cc{d}", .{@backingInt(self)}),
        }
    }