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.
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| @@ -73,8 +73,11 @@ ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3)) · 72 unmodified lines | ||
| 73 | 73 | |
| 74 | 74 | # __rustc-option |
| 75 | 75 | # Usage: MY_RUSTFLAGS += $(call __rustc-option,$(RUSTC),$(MY_RUSTFLAGS),-Cinstrument-coverage,-Zinstrument-coverage) |
| 76 | +# TODO: remove RUSTC_BOOTSTRAP=1 when we raise the minimum GNU Make version to 4.4 | |
| 76 | 77 | __rustc-option = $(call try-run,\ |
| 77 | − $(1) $(2) $(3) --crate-type=rlib /dev/null --out-dir=$$TMPOUT -o "$$TMP",$(3),$(4)) | |
| 78 | + echo '#![allow(missing_docs)]#![feature(no_core)]#![no_core]' | RUSTC_BOOTSTRAP=1\ | |
| 79 | + $(1) --sysroot=/dev/null $(filter-out --sysroot=/dev/null,$(2)) $(3)\ | |
| 80 | + --crate-type=rlib --out-dir=$(TMPOUT) --emit=obj=- - >/dev/null,$(3),$(4)) | |
| 78 | 81 | |
| 79 | 82 | # rustc-option |
| 80 | 83 | # Usage: rustflags-y += $(call rustc-option,-Cinstrument-coverage,-Zinstrument-coverage) |