Re: Make '-frust-incomplete-and-experimental-compiler-do-not-use' a 'Common' option (was: Rust front-end patches v4)

[Richard Biener <richard.guenther@gmail.com>]

On Wed, Dec 14, 2022 at 11:58 PM Thomas Schwinge
<thomas@codesourcery.com> wrote:
>
> Hi!
>
> On 2022-12-13T14:40:36+0100, Arthur Cohen <arthur.cohen@embecosm.com> wrote:
> > We've also added one more commit, which only affects files inside the
> > Rust front-end folder. This commit adds an experimental flag, which
> > blocks the compilation of Rust code when not used.
>
> (That's commit r13-4675-gb07ef39ffbf4e77a586605019c64e2e070915ac3
> "gccrs: Add fatal_error when experimental flag is not present".)
>
> I noticed that GCC/Rust recently lost all LTO variants in torture
> testing -- due to this commit.  :-O
>
> OK to push the attached
> "Make '-frust-incomplete-and-experimental-compiler-do-not-use' a 'Common' option",
> or should this be done differently?

Just add 'LTO' to the option in lang.opt, like

frust-incomplete-and-experimental-compiler-do-not-use
Rust LTO Var(flag_rust_experimental)
Enable experimental compilation of Rust files at your own risk


>
> With that, we get back:
>
>      PASS: rust/compile/torture/all_doc_comment_line_blocks.rs   -O0  (test for excess errors)
>      PASS: rust/compile/torture/all_doc_comment_line_blocks.rs   -O1  (test for excess errors)
>      PASS: rust/compile/torture/all_doc_comment_line_blocks.rs   -O2  (test for excess errors)
>     +PASS: rust/compile/torture/all_doc_comment_line_blocks.rs   -O2 -flto -fno-use-linker-plugin -flto-partition=none  (test for excess errors)
>     +PASS: rust/compile/torture/all_doc_comment_line_blocks.rs   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  (test for excess errors)
>      PASS: rust/compile/torture/all_doc_comment_line_blocks.rs   -O3 -g  (test for excess errors)
>      PASS: rust/compile/torture/all_doc_comment_line_blocks.rs   -Os  (test for excess errors)
>
> Etc., and in total:
>
>                     === rust Summary for unix ===
>
>     # of expected passes            [-4990-]{+6718+}
>     # of expected failures          [-39-]{+51+}
>
>
> Grüße
>  Thomas
>
>
> > We hope this helps
> > indicate to users that the compiler is not yet ready, but can still be
> > experimented with :)
> >
> > We plan on removing that flag as soon as possible, but in the meantime,
> > we think it will help not creating divide within the Rust ecosystem, as
> > well as not waste Rust crate maintainers' time.
>
>
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