[PATCH] rust: compile libcore with edition 2024 for 1.87+

[PATCH] rust: compile libcore with edition 2024 for 1.87+

[Gary Guo]

Rust 1.87 (released on 2025-05-15) compiles core library with edition
2024 instead of 2021 [1]. Ensure that the edition matches libcore's
expectation to avoid potential breakage.

Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://github.com/rust-lang/rust/pull/138162 [1]
Closes: https://github.com/Rust-for-Linux/linux/issues/1163
Signed-off-by: Gary Guo <gary@garyguo.net>
---
 rust/Makefile | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/rust/Makefile b/rust/Makefile
index 3aca903a7d08..9e7f1ec06181 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -60,6 +60,12 @@ endif
 core-cfgs = \
     --cfg no_fp_fmt_parse
 
+ifeq ($(call rustc-min-version,108700),y)
+core-cfgs += --edition=2024
+else
+core-cfgs += --edition=2021
+endif
+
 # `rustc` recognizes `--remap-path-prefix` since 1.26.0, but `rustdoc` only
 # since Rust 1.81.0. Moreover, `rustdoc` ICEs on out-of-tree builds since Rust
 # 1.82.0 (https://github.com/rust-lang/rust/issues/138520). Thus workaround both
@@ -106,7 +112,7 @@ rustdoc-macros: $(src)/macros/lib.rs FORCE
 
 # Starting with Rust 1.82.0, skipping `-Wrustdoc::unescaped_backticks` should
 # not be needed -- see https://github.com/rust-lang/rust/pull/128307.
-rustdoc-core: private skip_flags = -Wrustdoc::unescaped_backticks
+rustdoc-core: private skip_flags = -Wrustdoc::unescaped_backticks --edition=2021
 rustdoc-core: private rustc_target_flags = $(core-cfgs)
 rustdoc-core: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
 	+$(call if_changed,rustdoc)
@@ -416,7 +422,7 @@ quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L
       cmd_rustc_library = \
 	OBJTREE=$(abspath $(objtree)) \
 	$(if $(skip_clippy),$(RUSTC),$(RUSTC_OR_CLIPPY)) \
-		$(filter-out $(skip_flags),$(rust_flags) $(rustc_target_flags)) \
+		$(filter-out $(skip_flags),$(rust_flags)) $(rustc_target_flags) \
 		--emit=dep-info=$(depfile) --emit=obj=$@ \
 		--emit=metadata=$(dir $@)$(patsubst %.o,lib%.rmeta,$(notdir $@)) \
 		--crate-type rlib -L$(objtree)/$(obj) \
@@ -483,7 +489,7 @@ $(obj)/helpers/helpers.o: $(src)/helpers/helpers.c $(recordmcount_source) FORCE
 $(obj)/exports.o: private skip_gendwarfksyms = 1
 
 $(obj)/core.o: private skip_clippy = 1
-$(obj)/core.o: private skip_flags = -Wunreachable_pub
+$(obj)/core.o: private skip_flags = -Wunreachable_pub --edition=2021
 $(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym))
 $(obj)/core.o: private rustc_target_flags = $(core-cfgs)
 $(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs \

base-commit: 172a9d94339cea832d89630b89d314e41d622bd8
-- 
2.47.2

Re: [PATCH] rust: compile libcore with edition 2024 for 1.87+

[Miguel Ojeda]

On Sat, May 17, 2025 at 10:56 AM Gary Guo <gary@garyguo.net> wrote:
>
> Rust 1.87 (released on 2025-05-15) compiles core library with edition
> 2024 instead of 2021 [1]. Ensure that the edition matches libcore's
> expectation to avoid potential breakage.
>
> Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
> Link: https://github.com/rust-lang/rust/pull/138162 [1]
> Closes: https://github.com/Rust-for-Linux/linux/issues/1163
> Signed-off-by: Gary Guo <gary@garyguo.net>

Cc'ing est31 -- I will add:

Reported-by: est31 <est31@protonmail.com>

Thanks!

Cheers,
Miguel

Re: [PATCH] rust: compile libcore with edition 2024 for 1.87+

[Alice Ryhl]

On Sat, May 17, 2025 at 09:55:59AM +0100, Gary Guo wrote:
> Rust 1.87 (released on 2025-05-15) compiles core library with edition
> 2024 instead of 2021 [1]. Ensure that the edition matches libcore's
> expectation to avoid potential breakage.
> 
> Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
> Link: https://github.com/rust-lang/rust/pull/138162 [1]
> Closes: https://github.com/Rust-for-Linux/linux/issues/1163
> Signed-off-by: Gary Guo <gary@garyguo.net>

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

Re: [PATCH] rust: compile libcore with edition 2024 for 1.87+

[Miguel Ojeda]

On Sat, May 17, 2025 at 10:56 AM Gary Guo <gary@garyguo.net> wrote:
>
> Rust 1.87 (released on 2025-05-15) compiles core library with edition
> 2024 instead of 2021 [1]. Ensure that the edition matches libcore's
> expectation to avoid potential breakage.
>
> Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
> Link: https://github.com/rust-lang/rust/pull/138162 [1]
> Closes: https://github.com/Rust-for-Linux/linux/issues/1163
> Signed-off-by: Gary Guo <gary@garyguo.net>

Applied to `rust-next` -- thanks everyone!

(I actually applied a couple days ago in advance of Monday's -next,
which explains the following report)

    [ J3m3 reported in Zulip [2] that the `rust-analyzer` target was
      broken after this patch -- indeed, we need to avoid `core-cfgs`
      since those are passed to the `rust-analyzer` target.

      So, instead, I tweaked the patch to create a new `core-edition`
      variable and explicitly mention the `--edition` flag instead of
      reusing `core-cfg`s.

      In addition, pass a new argument using this new variable to
      `generate_rust_analyzer.py` so that we set the right edition there.

      By the way, for future reference: the `filter-out` change is needed
      for Rust < 1.87, since otherwise we would skip the `--edition=2021`
      we just added, ending up with no edition flag, and thus the compiler
      would default to the 2015 one.

      [2] https://rust-for-linux.zulipchat.com/#narrow/channel/291565/topic/x/near/520206547

        - Miguel ]

I also added:

    Reported-by: est31 <est31@protonmail.com>

since est31 told Gary in RustWeek, and we discussed the patch there.

@Gary: I hope the changes are OK with you (I can put the
`generate_rust_analyzer` ones in a different commit if you prefer).
Thanks!

Cheers,
Miguel