Add error codes for libsyntax_ext

[GuillaumeGomez]

I intend to add error codes for libsyntax_ext as well. However, they cannot be used at stage 0 directly so I thought it might be possible to enable them at the stage 1 only so we can have access to the macros. However, the error code registration seems to not work this way. Currently I get the following error:

error: used diagnostic code E0660 not registered
  --> libsyntax_ext/asm.rs:93:25
   |
93 |                         span_err!(cx, sp, E0660, "malformed inline assembly");
   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

error: used diagnostic code E0661 not registered
   --> libsyntax_ext/asm.rs:151:33
    |
151 | /                                 span_err!(cx, sp, E0661,
152 | |                                           "output operand constraint lacks '=' or '+'");
    | |________________________________________________________________________________________^
    |
    = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

error: aborting due to 2 previous errors

error: Could not compile `syntax_ext`.

If anyone has an idea, I'd gladly take it. I'm trying to figure this out on my side as well. I also opened this PR to know if it was worth it to continue (maybe we don't want this?).

Anyway, any answer for both questions is very welcome!

cc @rust-lang/compiler

[pietroalbini]

@rust-lang/compiler, can we get someone to answer @GuillaumeGomez questions?

[nikomatsakis]

I have no idea what the problem is :(

[petrochenkov]

I personally have dislike to error codes in general.

[GuillaumeGomez]

That helps. 😆

[nikomatsakis]

@GuillaumeGomez where is your branch? did you opt into the feature gate?

[nikomatsakis]

oh, @eddyb also says that you need to do #[cfg(stage0)] until beta is fixed... so maybe try again when the next beta lands...?

[nikomatsakis]

see also:

rust/src/librustc/lib.rs

Lines 181 to 183 in b1f8e6f

	// Build the diagnostics array at the end so that the metadata includes error use sites.
	#[cfg(not(stage0))] // remove after the next snapshot
	__build_diagnostic_array! { librustc, DIAGNOSTICS }

[GuillaumeGomez]

I'll wait for next beta then.

[pietroalbini]

@GuillaumeGomez I think a new beta was released by now?

[GuillaumeGomez]

Cool, I'll come back to it then.

[GuillaumeGomez]

Updated.

[GuillaumeGomez]

Ah, right, the tests I added can only work on stage 2 compiler... Is there a way to make these two tests to be run only on stage 2?

[shepmaster]

This never got a reviewer...

r? @eddyb

[eddyb]

r? @nikomatsakis

[nikomatsakis]

Travis is unhappy, to start:

https://travis-ci.org/rust-lang/rust/builds/358583412#L1748

[GuillaumeGomez]

@nikomatsakis: yes because tests can only be run on stage2. Which is why I asked:

Ah, right, the tests I added can only work on stage 2 compiler... Is there a way to make these two tests to be run only on stage 2?

[eddyb]

@GuillaumeGomez I think it's // ignore-stage1 (if you search around, there should be examples).

[GuillaumeGomez]

Thanks @eddyb!

[nikomatsakis]

Grammatical nit: I don't think of "syntax" as something you can have "one" of. I would rather say, "The argument to the asm macro is not well-formed" or something like that, perhaps?

[GuillaumeGomez]

Fine by me!

[GuillaumeGomez]

Fixed tests.

[estebank]

@bors r+

[bors]

📌 Commit f367567 has been approved by estebank

[bors]

⌛ Testing commit f367567 with merge d4d43e2...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: estebank
Pushing d4d43e2 to master...

[RalfJung]

However, they cannot be used at stage 0 directly

Care to explain why? Was this just a problem with the old bootstrap compiler?

This stage-0-conditional is still present in current master, and causing confusion like #53380

[GuillaumeGomez]

We need some macros (which are defined later on) to be defined.

[RalfJung]

But why are those not in the beta bootstrap compiler?

I do not understand how what you said relates to my question. :)

[GuillaumeGomez]

Hard to explain since I don't have the precise context in mind. Just gave you what I had in memory. ;)