Re: [PATCH v2] Kbuild: fix issues with rustc-option

[Alice Ryhl <aliceryhl@google.com>]

On Tue, Oct 8, 2024 at 9:00 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> On Wed, Oct 9, 2024 at 2:32 AM Alice Ryhl <aliceryhl@google.com> wrote:
> > diff --git a/scripts/Makefile.compiler b/scripts/Makefile.compiler
> > index 057305eae85c..08d5b7177ea8 100644
> > --- a/scripts/Makefile.compiler
> > +++ b/scripts/Makefile.compiler
> > @@ -21,6 +21,7 @@ TMPOUT = $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_$$$$
> >  # automatically cleaned up.
> >  try-run = $(shell set -e;              \
> >         TMP=$(TMPOUT)/tmp;              \
> > +       export RUSTC_BOOTSTRAP=1;       \
>
>
> try-run is not Rust-specific.
>
> Is there any reason why you did not add it
> to __rustc-option?
>
>
> __rustc-option = $(call try-run,\
>        RUSTC_BOOTSTRAP=1 $(1) $(2) $(3) --crate-type=rlib
> $(srctree)/rust/probe.rs --out-dir=$$TMP,$(3),$(4))

I had an explanation for this in the commit message, but it looks like
it got lost when I rewrote it for v2. Anyway, the reason is that I'd
have to modify both __rustc-option and rustc-option-yn to do that, and
putting it here seemed more future-proof against making the same
mistake in any rustc-* commands added in the future.

But I realize that it's not clear-cut. I'm happy to move it if you prefer,
or perhaps add a try-run-rust. Let me know what you think.

> I guess it is still suspicious because the top-level Makefile
> exports RUCTC_BOOTSTRAP.

Moving the declaration of RUSTC_BOOTSTRAP to the top of the Makefile
seems to fix it. I guess moving it is probably a better solution than
adding it in scripts/Makefile.compiler.

Not that I really understand why that is. The existing invocations are
in scripts/Makefile.kasan which is invoked after RUSTC_BOOTSTRAP is
declared.


Alice