Implement lazy loading of external crates' sources. Fixes#38875Fixes#38875. This is a follow-up to #42507. When a (now correctly translated) span from an external crate is referenced in a error, warning or info message, we still don't have the source code being referenced.
Since stuffing the source in the serialized metadata of an rlib is extremely wasteful, the following scheme has been implemented:
* File maps now contain a source hash that gets serialized as well.
* When a span is rendered in a message, the source hash in the corresponding file map(s) is used to try and load the source from the corresponding file on disk. If the file is not found or the hashes don't match, the failed attempt is recorded (and not retried).
* The machinery fetching source lines from file maps is augmented to use the lazily loaded external source as a secondary fallback for file maps belonging to external crates.
This required a small change to the expected stderr of one UI test (it now renders a span, where previously was none).
Further work can be done based on this - some of the machinery previously used to hide external spans is possibly obsolete and the hashing code can be reused in different places as well.
r? @eddyb
Remove struct_field_attributes feature gate
Part of #41681. ~This PR only removes the feature gate; this *does not* update any documentations.~ This PR removes the feature gate and the corresponding chapter of the Unstable Book.
I'm not very sure about the changes I made though... Just followed the stabilization guideline.
r? @nikomatsakis
Refactor variance and remove last `[pub]` map
This PR refactors variance to work in a more red-green friendly way. Because red-green doesn't exist yet, it has to be a bit hacky. The basic idea is this:
- We compute a big map with the variance for all items in the crate; when you request variances for a particular item, we read it from the crate
- We now hard-code that traits are invariant (which they are, for deep reasons, not gonna' change)
- When building constraints, we compute the transitive closure of all things within the crate that depend on what using `TransitiveRelation`
- this lets us gin up the correct dependencies when requesting variance of a single item
Ah damn, just remembered, one TODO:
- [x] Update the variance README -- ah, I guess the README updates I did are sufficient
r? @michaelwoerister
There are now two queries: crate and item. The crate one computes the
variance of all items in the crate; it is sort of an implementation
detail, and not meant to be used. The item one reads from the crate one,
synthesizing correct deps in lieu of the red-green algorithm.
At the same time, remove the `variance_computed` flag, which was a
horrible hack used to force invariance early on (e.g. when type-checking
constants). This is only needed because of trait applications, and
traits are always invariant anyway. Therefore, we now change to take
advantage of the query system:
- When asked to compute variances for a trait, just return a vector
saying 'all invariant'.
- Remove the corresponding "inferreds" from traits, and tweak the
constraint generation code to understand that traits are always
inferred.
Removal pass for anonymous parameters
Removes occurences of anonymous parameters from the
rustc codebase, as they are to be deprecated.
See issue #41686 and RFC 1685.
r? @frewsxcv
Handle subtyping in inference through obligations
We currently store subtyping relations in the `TypeVariables` structure as a kind of special case. This branch uses normal obligations to propagate subtyping, thus converting our inference variables into normal fallback. It also does a few other things:
- Removes the (unstable, outdated) support for custom type inference fallback.
- It's not clear how we want this to work, but we know that we don't want it to work the way it currently does.
- The existing support was also just getting in my way.
- Fixes#30225, which was caused by the trait caching code pretending type variables were normal unification variables, when indeed they were not (but now are).
There is one fishy part of these changes: when computing the LUB/GLB of a "bivariant" type parameter, I currently return the `a` value. Bivariant type parameters are only allowed in a very particular situation, where the type parameter is only used as an associated type output, like this:
```rust
pub struct Foo<A, B>
where A: Fn() -> B
{
data: A
}
```
In principle, if one had `T=Foo<A, &'a u32>` and `U=Foo<A, &'b u32>` and (e.g.) `A: for<'a> Fn() -> &'a u32`, then I think that computing the LUB of `T` and `U` might do the wrong thing. Probably the right behavior is just to create a fresh type variable. However, that particular example would not compile (because the where-clause is illegal; `'a` does not appear in any input type). I was not able to make an example that *would* compile and demonstrate this shortcoming, and handling the LUB/GLB was mildly inconvenient, so I left it as is. I am considering whether to revisit this or what.
I have started a crater run to test the impact of these changes.
Instead of collecting all potential inputs to some metadata entry and
hashing those, we directly hash the values we are storing in metadata.
This is more accurate and doesn't suffer from quadratic blow-up when
many entries have the same dependencies.
rustbuild: Update bootstrap compiler
Now that we've also updated cargo's release process this commit also changes the
download location of Cargo from Cargos archives back to the static.r-l.o
archives. This should ensure that the Cargo download is the exact Cargo paired
with the rustc that we release.
Now that we've also updated cargo's release process this commit also changes the
download location of Cargo from Cargos archives back to the static.r-l.o
archives. This should ensure that the Cargo download is the exact Cargo paired
with the rustc that we release.
This commit deletes the internal liblog in favor of the implementation that
lives on crates.io. Similarly it's also setting a convention for adding crates
to the compiler. The main restriction right now is that we want compiler
implementation details to be unreachable from normal Rust code (e.g. requires a
feature), and by default everything in the sysroot is reachable via `extern
crate`.
The proposal here is to require that crates pulled in have these lines in their
`src/lib.rs`:
#![cfg_attr(rustbuild, feature(staged_api, rustc_private))]
#![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))]
This'll mean that by default they're not using these attributes but when
compiled as part of the compiler they do a few things:
* Mark themselves as entirely unstable via the `staged_api` feature and the
`#![unstable]` attribute.
* Allow usage of other unstable crates via `feature(rustc_private)` which is
required if the crate relies on any other crates to compile (other than std).
[MIR] SwitchInt Everywhere
Something I've been meaning to do for a very long while. This PR essentially gets rid of 3 kinds of conditional branching and only keeps the most general one - `SwitchInt`. Primary benefits are such that dealing with MIR now does not involve dealing with 3 different ways to do conditional control flow. On the other hand, constructing a `SwitchInt` currently requires more code than what previously was necessary to build an equivalent `If` terminator. Something trivially "fixable" with some constructor methods somewhere (MIR needs stuff like that badly in general).
Some timings (tl;dr: slightly faster^1 (unexpected), but also uses slightly more memory at peak (expected)):
^1: Not sure if the speed benefits are because of LLVM liking the generated code better or the compiler itself getting compiled better. Either way, its a net benefit. The CORE and SYNTAX timings done for compilation without optimisation.
```
AFTER:
Building stage1 std artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 31.50 secs
Finished release [optimized] target(s) in 31.42 secs
Building stage1 compiler artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 439.56 secs
Finished release [optimized] target(s) in 435.15 secs
CORE: 99% (24.81 real, 0.13 kernel, 24.57 user); 358536k resident
CORE: 99% (24.56 real, 0.15 kernel, 24.36 user); 359168k resident
SYNTAX: 99% (49.98 real, 0.48 kernel, 49.42 user); 653416k resident
SYNTAX: 99% (50.07 real, 0.58 kernel, 49.43 user); 653604k resident
BEFORE:
Building stage1 std artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 31.84 secs
Building stage1 compiler artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
Finished release [optimized] target(s) in 451.17 secs
CORE: 99% (24.66 real, 0.20 kernel, 24.38 user); 351096k resident
CORE: 99% (24.36 real, 0.17 kernel, 24.18 user); 352284k resident
SYNTAX: 99% (52.24 real, 0.56 kernel, 51.66 user); 645544k resident
SYNTAX: 99% (51.55 real, 0.48 kernel, 50.99 user); 646428k resident
```
cc @nikomatsakis @eddyb
This removes another special case of Switch by replacing it with the more general SwitchInt. While
this is more clunky currently, there’s no reason we can’t make it nice (and efficient) to use.
This commit updates the version number to 1.17.0 as we're not on that version of
the nightly compiler, and at the same time this updates src/stage0.txt to
bootstrap from freshly minted beta compiler and beta Cargo.
Like many hash functions, the blake2 hash is mathematically defined on
a sequence of 64-bit words. As Rust's hash interface operates on
sequences of octets, some encoding must be used to bridge that
difference.
The Blake2 RFC (RFC 7693) specifies that:
Byte (octet) streams are interpreted as words in little-endian order,
with the least-significant byte first.
So use that encoding consistently.
Fixes#38891.
Remove not(stage0) from deny(warnings)
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
