Issue 56128 segment id ice nightly#56143

nikomatsakis · 2018-11-21T19:23:30Z

Tentative fix for #56128

From what I can tell, the problem is that if you have pub(super) use foo::{a, b}, then when we explode the a and b, the segment ids from the super path were not getting cloned. However, once I fixed that, then I ran into a problem that the "visibility" node-ids were not present in the final HIR -- this is because the visibility of the "stem" that is returned in this case was getting reset to inherited. I don't think it is a problem to undo that, so that the visibility is returned unmodified.

Fixes #55475
Fixes #56128

cc @nrc @petrochenkov

rust-highfive · 2018-11-21T19:23:33Z

r? @varkor

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rust-highfive · 2018-11-21T19:23:34Z

⚠️ Warning ⚠️

These commits modify submodules.

nikomatsakis · 2018-11-21T19:23:46Z

r? @petrochenkov

nrc

Did you mean to update the submodules?

LGTM otherwise

nikomatsakis · 2018-11-21T20:33:20Z

Er, no, no I did not.

Without this, the `vis` does not wind up in the tree anywhere, and then we get ICEs because the node-ids it refers to are not present. The motivation seemed to be documentation, but `ListStem` HIR nodes are ignored in rustdoc, from what I can tell.

We are not mutating it now.

nikomatsakis · 2018-11-21T20:35:03Z

I guess though that this is fallout from the visibility change:

[00:48:29] ---- [ui] ui/lint/unreachable_pub-pub_crate.rs stdout ----
[00:48:29] diff of stderr:
[00:48:29] 
[00:48:29] 14    = help: or consider exporting it for use by other crates
[00:48:29] 15 
[00:48:29] 16 warning: unreachable `pub` item
[00:48:29] +   --> $DIR/unreachable_pub-pub_crate.rs:26:5
[00:48:29] +    |
[00:48:29] + LL |     pub use std::env::{Args}; // braced-use has different item spans than unbraced
[00:48:29] +    |     ---^^^^^^^^^^^^^^^
[00:48:29] +    |     |
[00:48:29] +    |     help: consider restricting its visibility: `pub(crate)`
[00:48:29] +    |
[00:48:29] +    = help: or consider exporting it for use by other crates
[00:48:29] + 
[00:48:29] + warning: unreachable `pub` item
[00:48:29] 18    |
[00:48:29] 18    |
[00:48:29] 19 LL |     pub use std::env::{Args}; // braced-use has different item spans than unbraced

nikomatsakis · 2018-11-21T20:35:16Z

I can make that code ignore ListStem but..ugh.

nikomatsakis · 2018-11-21T21:10:21Z

I tried an alternate fix (use the vis for the last item) but it ice'd because the owner was wrong; more notes from discord here.

I don't have a better idea than what's in this PR -- I leave it to @nrc and @petrochenkov to decide best course of action =)

alexcrichton · 2018-11-21T22:09:01Z

@bors: p=1

we're gonna want to backport this

petrochenkov · 2018-11-22T00:06:41Z

src/librustc/hir/lowering.rs

-                // a re-export by accident when `pub`, e.g. in documentation.
                let def = self.expect_full_def_from_use(id).next().unwrap_or(Def::Err);
                let path = P(self.lower_path_extra(def, &prefix, ParamMode::Explicit, None));
-                *vis = respan(prefix.span.shrink_to_lo(), hir::VisibilityKind::Inherited);


IIRC, you still need to reset at least pub (hir::VisibilityKind::Public) into something more private, otherwise you'll get a lot of noise from rustdoc (the stem is emitted for all braced imports).

This way the hack for UnreachablePub can be avoided as well.

This should be ok since hir::VisibilityKind::Public doesn't have a path with node IDs inside it.

Everything except for VisibilityKind::Restricted can be reset to VisibilityKind::Inherited basically.

petrochenkov · 2018-11-22T00:12:34Z

Beside #56143 (comment) everything looks reasonable.

(I never fully understood what are relations between node ids, def ids, their owners, parents, etc though, and why @QuietMisdreavus had to do all those horrible things with them in #51425.)

petrochenkov · 2018-11-22T20:14:05Z

@bors r+

bors · 2018-11-22T20:14:06Z

📌 Commit 5f2a173 has been approved by petrochenkov

bors · 2018-11-22T20:29:58Z

⌛ Testing commit 5f2a173 with merge 00e03ee...

@nrc

…y, r=petrochenkov Issue 56128 segment id ice nightly Tentative fix for #56128 From what I can tell, the problem is that if you have `pub(super) use foo::{a, b}`, then when we explode the `a` and `b`, the segment ids from the `super` path were not getting cloned. However, once I fixed *that*, then I ran into a problem that the "visibility" node-ids were not present in the final HIR -- this is because the visibility of the "stem" that is returned in this case was getting reset to inherited. I don't *think* it is a problem to undo that, so that the visibility is returned unmodified. Fixes #55475 Fixes #56128 cc @nrc @petrochenkov

bors · 2018-11-22T23:25:22Z

☀️ Test successful - status-appveyor, status-travis
Approved by: petrochenkov
Pushing 00e03ee to master...

@ghost

[beta] Rollup backports * #56163: [master] Backport 1.30.1 release notes * #56147: resolve: Fix some asserts in import validation * #56118: Update books for Rust 2018 * #56117: resolve: Make "empty import canaries" invisible from other crates * #56065: Replace the ICEing on const fn loops with an error * #56143: Issue 56128 segment id ice nightly * #56134: Fix clippy documentation links (first in #56156) r? @ghost

nikomatsakis added 3 commits November 21, 2018 13:41

track the span for each id so that we can give a nice ICE

d0a174d

add some debug! into lowering

40f8094

renumber segment ids for visibilities whenever we clone them

a0a4790

rust-highfive assigned varkor Nov 21, 2018

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Nov 21, 2018

rust-highfive assigned petrochenkov and unassigned varkor Nov 21, 2018

This was referenced Nov 21, 2018

Panic rustc 1.31.0-nightly (96064eb61 2018-10-28) running on x86_64-pc-windows-msvc: in hir_id_validator.rs:31 #55475

Closed

Beta ICE: ItemLocalIds not assigned densely #56128

Closed

alexcrichton added this to the Rust 2018 Release milestone Nov 21, 2018

alexcrichton added beta-nominated Nominated for backporting to the compiler in the beta channel. beta-accepted Accepted for backporting to the compiler in the beta channel. labels Nov 21, 2018

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nrc reviewed Nov 21, 2018

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nikomatsakis added 3 commits November 21, 2018 15:34

add regression test

2bd2fc9

pass vis by shared reference

4c7ce7c

We are not mutating it now.

nikomatsakis force-pushed the issue-56128-segment-id-ice-nightly branch from 3440713 to 4c7ce7c Compare November 21, 2018 20:34

hack: ignore list-stems for pub lint

9cdf491

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add compile-pass annotation

ebf3c8d

petrochenkov reviewed Nov 22, 2018

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nikomatsakis added 2 commits November 22, 2018 09:38

only reset non-restricted visibilities

b83150e

explain how this works

5f2a173

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 22, 2018

emilyalbini mentioned this pull request Nov 22, 2018

[beta] Rollup backports #56174

Merged

bors merged commit 5f2a173 into rust-lang:master Nov 22, 2018

alexcrichton removed the beta-nominated Nominated for backporting to the compiler in the beta channel. label Nov 23, 2018

DJMcNab mentioned this pull request Dec 9, 2018

ra_syntax fails to compile with rustc 1.31.0-nightly (96064eb 2018-10-28) rust-lang/rust-analyzer#185

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ljedrz mentioned this pull request Feb 14, 2019

HirId-ify intravisit #58232

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