On Wed, Mar 12, 2025 at 5:01 PM Benno Lossin [off-list ref] wrote:

On Wed Mar 12, 2025 at 9:41 PM CET, Tamir Duberstein wrote:

quoted

On Wed, Mar 12, 2025 at 4:07 PM Tamir Duberstein [off-list ref] wrote:

quoted

On Wed, Mar 12, 2025 at 3:43 PM Benno Lossin [off-list ref] wrote:

quoted

On Wed Mar 12, 2025 at 8:19 PM CET, Tamir Duberstein wrote:

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I tried using the strict provenance lints locally and I think we can't
until we properly bump MSRV due to `clippy::incompatible_msrv`:

warning: current MSRV (Minimum Supported Rust Version) is `1.78.0` but
this item is stable since `1.84.0`
   --> ../rust/kernel/str.rs:696:22
    |
696 |             pos: pos.expose_provenance(),
    |                      ^^^^^^^^^^^^^^^^^^^
    |
    = help: for further information visit
https://rust-lang.github.io/rust-clippy/master/index.html#incompatible_msrv

Oh this is annoying...

quoted

This is with `#![feature(strict_provenance)]`. I can file the issue
but I think it's blocked on MSRV >= 1.84.0. But maybe you know of a
path forward :)

I think we should be able to just `allow(clippy::incompatible_msrv)`,
since Miguel & other maintainers will test with 1.78 (or at least are
supposed to :).

Alright, you've sniped me. This is coming in v3.

I just realized I only covered the kernel crate. In order to cover all
Rust code, I need to move the lints and the features out to the root
Makefile. I tried something like this:

quoted

diff --git a/Makefile b/Makefile
index 2af40bfed9ce..10af1e44370b 100644
--- a/Makefile
+++ b/Makefile

@@ -466,13 +466,21 @@ KBUILD_USERHOSTCFLAGS := -Wall -Wmissing-prototypes -Wstrict-prototypes \
 KBUILD_USERCFLAGS  := $(KBUILD_USERHOSTCFLAGS) $(USERCFLAGS)
 KBUILD_USERLDFLAGS := $(USERLDFLAGS)

+# Lints were moved to `strict_provenance_lints` when `strict_provenance` was stabilized.
+#
+# See https://github.com/rust-lang/rust/commit/56ee492a6e7a917b2b3f888e33dd52a13d3ecb64.
+KBUILD_RUST_STRICT_PROVENANCE_FEATURE = $(if $(CONFIG_RUSTC_HAS_STABLE_STRICT_PROVENANCE),strict_provenance_lints,strict_provenance)
+
 # These flags apply to all Rust code in the tree, including the kernel and
 # host programs.
 export rust_common_flags := --edition=2021 \
     -Zbinary_dep_depinfo=y \
+     -Zcrate-attr="feature($(KBUILD_RUST_STRICT_PROVENANCE_FEATURE))" \
     -Astable_features \
     -Dnon_ascii_idents \
     -Dunsafe_op_in_unsafe_fn \
+     -Wfuzzy_provenance_casts \
+     -Wlossy_provenance_casts \
     -Wmissing_docs \
     -Wrust_2018_idioms \
     -Wunreachable_pub \

diff --git a/rust/Makefile b/rust/Makefile
index ea3849eb78f6..d7d5be741245 100644
--- a/rust/Makefile
+++ b/rust/Makefile

@@ -435,8 +435,10 @@ $(obj)/helpers/helpers.o: $(src)/helpers/helpers.c $(recordmcount_source) FORCE
 # symbol versions generated from Rust objects.
 $(obj)/exports.o: private skip_gendwarfksyms = 1

+KBUILD_RUST_STRICT_PROVENANCE_FEATURE := $(if $(CONFIG_RUSTC_HAS_STABLE_STRICT_PROVENANCE),strict_provenance_lints,strict_provenance)
+
 $(obj)/core.o: private skip_clippy = 1
-$(obj)/core.o: private skip_flags = -Wunreachable_pub
+$(obj)/core.o: private skip_flags = -Zcrate-attr="feature($(KBUILD_RUST_STRICT_PROVENANCE_FEATURE))" -Wunreachable_pub -Wfuzzy_provenance_casts -Wlossy_provenance_casts
 $(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 \

but this doesn't work because
`CONFIG_RUSTC_HAS_STABLE_STRICT_PROVENANCE` is not yet defined when I
read it in the root Makefile. I can read it lower down and then append
the feature flag to `KBUILD_RUSTFLAGS` but by then the rustdoc flags
have been copied from `rust_common_flags` and so rustdoc doesn't get
the feature flag, resulting in unknown lint warnings in rustdoc and
kunit tests.

Any ideas?

Always enable the features, we have `allow(stable_features)` for this
reason (then you don't have to do this dance with checking if it's
already stable or not :)

It's not so simple. In rustc < 1.84.0 the lints *and* the strict
provenance APIs are behind `feature(strict_provenance)`. In rustc >=
1.84.0 the lints are behind `feature(strict_provenance_lints)`. So you
need to read the config to learn that you need to enable
`feature(strict_provenance_lints)`.