Re: [PATCH] rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

[Trevor Gross]

On Sat Nov 1, 2025 at 4:40 AM CDT, Miguel Ojeda wrote:
> Rust 1.93.0 (expected 2026-01-22) is stabilizing `-Zno-jump-tables`
> [1][2] as `-Cjump-tables=n` [3].
>
> Without this change, one would eventually see:
>
>       RUSTC L rust/core.o
>     error: unknown unstable option: `no-jump-tables`
>
> Thus support the upcoming version.
>
> Link: https://github.com/rust-lang/rust/issues/116592 [1]
> Link: https://github.com/rust-lang/rust/pull/105812 [2]
> Link: https://github.com/rust-lang/rust/pull/145974 [3]
> Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx>

Reviewed-by: Trevor Gross <tmgross@xxxxxxxxx>

> ---
>  arch/loongarch/Makefile | 2 +-
>  arch/x86/Makefile       | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
> index dc5bd3f1b8d2..96ca1a688984 100644
> --- a/arch/loongarch/Makefile
> +++ b/arch/loongarch/Makefile
> @@ -109,7 +109,7 @@ endif
>  ifdef CONFIG_RUSTC_HAS_ANNOTATE_TABLEJUMP
>  KBUILD_RUSTFLAGS		+= -Cllvm-args=--loongarch-annotate-tablejump
>  else
> -KBUILD_RUSTFLAGS		+= -Zno-jump-tables # keep compatibility with older compilers
> +KBUILD_RUSTFLAGS		+= $(if $(call rustc-min-version,109300),-Cjump-tables=n,-Zno-jump-tables) # keep compatibility with older compilers
>  endif
>  ifdef CONFIG_LTO_CLANG
>  # The annotate-tablejump option can not be passed to LLVM backend when LTO is enabled.
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index 4db7e4bf69f5..c60371db49d9 100644
> --- a/arch/x86/Makefile
> +++ b/arch/x86/Makefile
> @@ -98,7 +98,7 @@ ifeq ($(CONFIG_X86_KERNEL_IBT),y)
>  #   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104816
>  #
>  KBUILD_CFLAGS += $(call cc-option,-fcf-protection=branch -fno-jump-tables)
> -KBUILD_RUSTFLAGS += -Zcf-protection=branch -Zno-jump-tables
> +KBUILD_RUSTFLAGS += -Zcf-protection=branch $(if $(call rustc-min-version,109300),-Cjump-tables=n,-Zno-jump-tables)
>  else
>  KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
>  endif
>
> base-commit: dcb6fa37fd7bc9c3d2b066329b0d27dedf8becaa