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authorAlice Ryhl <aliceryhl@google.com>2024-10-09 11:41:59 +0000
committerMiguel Ojeda <ojeda@kernel.org>2024-10-10 22:34:41 +0200
commite72a076c620f692b405dd6c39e8a7c98c8a59ecc (patch)
tree323e288ae959b39ceeb63c3754d7527b82093aee
parentb55da84759c8c21ec0c7441c519fc1d07dc4c65c (diff)
kbuild: fix issues with rustc-option
Fix a few different compiler errors that cause rustc-option to give wrong results. If KBUILD_RUSTFLAGS or the flags being tested contain any -Z flags, then the error below is generated. The RUSTC_BOOTSTRAP environment variable is added to fix this error. error: the option `Z` is only accepted on the nightly compiler help: consider switching to a nightly toolchain: `rustup default nightly` note: selecting a toolchain with `+toolchain` arguments require a rustup proxy; see <https://rust-lang.github.io/rustup/concepts/index.html> note: for more information about Rust's stability policy, see <https://doc.rust-lang.org/book/appendix-07-nightly-rust.html#unstable-features> error: 1 nightly option were parsed Note that RUSTC_BOOTSTRAP is also defined in the top-level Makefile, but Make-exported variables are unfortunately *not* inherited. That said, this is changing as of commit 98da874c4303 ("[SV 10593] Export variables to $(shell ...) commands"), which is part of Make 4.4. The probe may also fail with the error message below. To fix it, the /dev/null argument is replaced with a file containing the crate attribute #![no_core]. The #![no_core] attribute ensures that rustc does not look for the standard library. It's not possible to instead supply a standard library (i.e. `core`) to rustc, as we need `rustc-option` before the Rust standard library is compiled. error[E0463]: can't find crate for `std` | = note: the `aarch64-unknown-none` target may not be installed = help: consider downloading the target with `rustup target add aarch64-unknown-none` = help: consider building the standard library from source with `cargo build -Zbuild-std` The -o and --out-dir parameters are altered to fix this warning: warning: ignoring --out-dir flag due to -o flag The --sysroot flag is provided as we would otherwise require it to be present in KBUILD_RUSTFLAGS. The --emit=obj flag is used to write the resulting object file to /dev/null instead of writing it to a file in $(TMPOUT). I verified that the Kconfig version of rustc-option doesn't have the same issues. Fixes: c42297438aee ("kbuild: rust: Define probing macros for rustc") Co-developed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Alice Ryhl <aliceryhl@google.com> Acked-by: Masahiro Yamada <masahiroy@kernel.org> Link: https://lore.kernel.org/r/20241009-rustc-option-bootstrap-v3-1-5fa0d520efba@google.com [ Reworded as discussed in the list. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
-rw-r--r--scripts/Makefile.compiler5
1 files changed, 4 insertions, 1 deletions
diff --git a/scripts/Makefile.compiler b/scripts/Makefile.compiler
index 73d611d383b2..e0842496d26e 100644
--- a/scripts/Makefile.compiler
+++ b/scripts/Makefile.compiler
@@ -73,8 +73,11 @@ ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
# __rustc-option
# Usage: MY_RUSTFLAGS += $(call __rustc-option,$(RUSTC),$(MY_RUSTFLAGS),-Cinstrument-coverage,-Zinstrument-coverage)
+# TODO: remove RUSTC_BOOTSTRAP=1 when we raise the minimum GNU Make version to 4.4
__rustc-option = $(call try-run,\
- $(1) $(2) $(3) --crate-type=rlib /dev/null --out-dir=$$TMPOUT -o "$$TMP",$(3),$(4))
+ echo '#![allow(missing_docs)]#![feature(no_core)]#![no_core]' | RUSTC_BOOTSTRAP=1\
+ $(1) --sysroot=/dev/null $(filter-out --sysroot=/dev/null,$(2)) $(3)\
+ --crate-type=rlib --out-dir=$(TMPOUT) --emit=obj=- - >/dev/null,$(3),$(4))
# rustc-option
# Usage: rustflags-y += $(call rustc-option,-Cinstrument-coverage,-Zinstrument-coverage)