Erase regions in writeback #69189

matthewjasper · 2020-02-15T16:28:24Z

Regions in TypeckTables (except canonicalized user annotations) are now erased. Further, we no longer do lexical region solving on item bodies with -Zborrowck=mir.

cc #68261
r? @nikomatsakis

Avoid using regions from `TypeckTables` These regions will all be `ReErased` soon. (rust-lang/rust#69189) changelog: none

bors · 2020-02-17T02:06:34Z

☔ The latest upstream changes (presumably #67953) made this pull request unmergeable. Please resolve the merge conflicts.

joelpalmer · 2020-03-09T11:00:26Z

Triaged

nikomatsakis · 2020-03-12T14:30:09Z

src/librustc_infer/infer/mod.rs

-#[derive(Copy, Clone, Default, Debug)]
-pub struct SuppressRegionErrors {
-    suppressed: bool,
+#[derive(Copy, Clone, Debug)]


Can we add a doc comment explaining the overall role of this type?

I was imagining that we might give some coverage of how regions are handled in type-check vs NLL here. Though really we ought to explain this in a rustc-dev-guide section and link to that

nikomatsakis · 2020-03-12T14:57:44Z

r=me with a comment, cc @matthewjasper

matthewjasper · 2020-03-12T19:45:18Z

@bors r=nikomatsakis

bors · 2020-03-12T19:45:20Z

📌 Commit f8a08a9 has been approved by nikomatsakis

@nikomatsakis

…komatsakis Erase regions in writeback Regions in `TypeckTables` (except canonicalized user annotations) are now erased. Further, we no longer do lexical region solving on item bodies with `-Zborrowck=mir`. cc rust-lang#68261 r? @nikomatsakis

@ghost

Rollup of 8 pull requests Successful merges: - #68746 (Make macro metavars respect (non-)hygiene) - #69189 (Erase regions in writeback) - #69402 (Extend search) - #69403 (Implement `Copy` for `IoSlice`) - #69460 (Move some `build-pass` tests to `check-pass`) - #69802 (fix more clippy findings) - #69809 (remove lifetimes that can be elided (clippy::needless_lifetimes)) - #69949 (triagebot.toml: add ping aliases) Failed merges: - #69589 (ast: `Mac`/`Macro` -> `MacCall`) r? @ghost

bors · 2020-03-14T20:04:14Z

☔ The latest upstream changes (presumably #69076) made this pull request unmergeable. Please resolve the merge conflicts.

@nikomatsakis

…komatsakis Erase regions in writeback Regions in `TypeckTables` (except canonicalized user annotations) are now erased. Further, we no longer do lexical region solving on item bodies with `-Zborrowck=mir`. cc rust-lang#68261 r? @nikomatsakis

@nikomatsakis

…komatsakis Erase regions in writeback Regions in `TypeckTables` (except canonicalized user annotations) are now erased. Further, we no longer do lexical region solving on item bodies with `-Zborrowck=mir`. cc rust-lang#68261 r? @nikomatsakis

@ghost

Rollup of 10 pull requests Successful merges: - rust-lang#67749 (keyword docs for else and inkeyword docs for else and in.) - rust-lang#69139 (clean up E0308 explanation) - rust-lang#69189 (Erase regions in writeback) - rust-lang#69837 (Use smaller discriminants for generators) - rust-lang#69838 (Expansion-driven outline module parsing) - rust-lang#69839 (Miri error reform) - rust-lang#69899 (Make methods declared by `newtype_index` macro `const`) - rust-lang#69920 (Remove some imports to the rustc crate) - rust-lang#70075 (Fix repr pretty display) - rust-lang#70106 (Tidy: fix running rustfmt twice) Failed merges: - rust-lang#70051 (Allow `hir().find` to return `None`) - rust-lang#70074 (Expand: nix all fatal errors) r? @ghost

eddyb · 2020-03-19T07:43:10Z

src/test/ui/transmute/main.stderr

@@ -4,8 +4,7 @@ error[E0512]: cannot transmute between types of different sizes, or dependently-
 LL |     transmute(x)
   |     ^^^^^^^^^
   |
-   = note: source type: `<C as TypeConstructor<'a>>::T` (size can vary because of <C as TypeConstructor>::T)
-   = note: target type: `<C as TypeConstructor<'b>>::T` (size can vary because of <C as TypeConstructor>::T)
+   = note: `<C as TypeConstructor>::T` does not have a fixed size


Wait, we don't allow transmuting between the same type with only lifetimes changed?
I think we do when it's beyond a pointer, even if we don't know if it's Sized.

We don't allow transmutes between type projections at all it seems:

pub trait TypeConstructor { type T; } unsafe fn transmute_lifetime<C>(x: C::T) where C: TypeConstructor { transmute::<C::T, C::T>(x); // ERROR ! }

flip1995 · 2020-03-19T13:58:27Z

@matthewjasper Question regarding a Clippy rustup: rust-lang/rust-clippy#5333

Clippy has a check in the linting code that compares two types like this:

cx.tcx.expr_ty(expr1) == cx.tcx.expr_ty(expr2)

Before this PR, this returned false for &'a T == &'b T. Now it doesn't take the different lifetimes into account and returns true. Do you know of a way to compare two types taking their (user-defined) lifetimes into account?

rustup rust-lang/rust#69189 rustups rust-lang/rust#69189 which is part of rust-lang/rust#70085 (at least I think this is the only pr that changes clippy test stdout) changelog: none

eddyb · 2020-03-19T14:01:48Z

@flip1995 No, you were getting lucky before if that worked.
The only thing that can accurately reason about lifetimes is MIR borrowck.

@ghost

Rollup of 4 pull requests Successful merges: - #5326 (rustup rust-lang/rust#69838) - #5333 (rustup rust-lang/rust#69189) - #5336 (rustup rust-lang/rust#69920) - #5341 (Rustup to rust-lang/rust#66131) Failed merges: r? @ghost

@ghost

Rollup of 4 pull requests Successful merges: - #5326 (rustup rust-lang/rust#69838) - #5333 (rustup rust-lang/rust#69189) - #5336 (rustup rust-lang/rust#69920) - #5341 (Rustup to rust-lang/rust#66131) Failed merges: r? @ghost changelog: none

@ghost

Rollup of 4 pull requests Successful merges: - #5326 (rustup rust-lang/rust#69838) - #5333 (rustup rust-lang/rust#69189) - #5336 (rustup rust-lang/rust#69920) - #5341 (Rustup to rust-lang/rust#66131) Failed merges: r? @ghost changelog: none

@ghost

Rollup of 4 pull requests Successful merges: - #5326 (rustup rust-lang/rust#69838) - #5333 (rustup rust-lang/rust#69189) - #5336 (rustup rust-lang/rust#69920) - #5341 (Rustup to rust-lang/rust#66131) Failed merges: r? @ghost changelog: none

@ghost

Rollup of 4 pull requests Successful merges: - #5326 (rustup rust-lang/rust#69838) - #5333 (rustup rust-lang/rust#69189) - #5336 (rustup rust-lang/rust#69920) - #5341 (Rustup to rust-lang/rust#66131) Failed merges: r? @ghost changelog: none

rust-highfive assigned nikomatsakis Feb 15, 2020

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matthewjasper mentioned this pull request Feb 15, 2020

Avoid using regions from TypeckTables rust-lang/rust-clippy#5177

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bors added a commit to rust-lang/rust-clippy that referenced this pull request Feb 15, 2020

Auto merge of #5177 - matthewjasper:own-infer, r=flip1995

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Avoid using regions from `TypeckTables` These regions will all be `ReErased` soon. (rust-lang/rust#69189) changelog: none

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matthewjasper force-pushed the erase-the-world branch from 86161e0 to 5ce0263 Compare February 15, 2020 18:13

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Centril mentioned this pull request Mar 12, 2020

Rollup of 8 pull requests #69958

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nikomatsakis mentioned this pull request Mar 13, 2020

Make the type_of return a generic type for generators #68884

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bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Mar 14, 2020

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Centril mentioned this pull request Mar 18, 2020

Rollup of 8 pull requests #70099

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Centril mentioned this pull request Mar 18, 2020

Rollup of 10 pull requests #70109

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Centril mentioned this pull request Mar 18, 2020

Rollup of 10 pull requests #70110

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Centril mentioned this pull request Mar 18, 2020

Rollup of 10 pull requests #70112

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bors merged commit 3f583fc into rust-lang:master Mar 19, 2020

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flip1995 mentioned this pull request Mar 19, 2020

Rollup of 4 pull requests rust-lang/rust-clippy#5342

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flip1995 mentioned this pull request Mar 19, 2020

Regression in useless_transmute due to rustup rust-lang/rust-clippy#5343

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SimonSapin mentioned this pull request Mar 20, 2020

Importing modules from inside include! no longer works #70185

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Centril mentioned this pull request Mar 31, 2020

internal compiler error: cannot relate region: LUB(ReErased, ReErased) #70608

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matthewjasper mentioned this pull request May 20, 2020

Don't infer regions in type checking #68261

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jplatte mentioned this pull request May 27, 2020

ICE with const_generics + const_compare_raw_pointers: broken MIR / NoSolution #72352

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Erase regions in writeback #69189

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Erase regions in writeback #69189

Erase regions in writeback #69189

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