bors [Mon, 16 Mar 2020 20:49:26 +0000 (20:49 +0000)]
Auto merge of #68970 - matthewjasper:min-spec, r=nikomatsakis
Implement a feature for a sound specialization subset
This implements a new feature (`min_specialization`) that restricts specialization to a subset that is reasonable for the standard library to use.
The plan is to then:
* Update `libcore` and `liballoc` to compile with `min_specialization`.
* Add a lint to forbid use of `feature(specialization)` (and other unsound, type system extending features) in the standard library.
* Fix the soundness issues around `specialization`.
* Remove `min_specialization`
The rest of this is an overview from a comment in this PR
## Basic approach
To enforce this requirement on specializations we take the following approach:
1. Match up the substs for `impl2` so that the implemented trait and self-type match those for `impl1`.
2. Check for any direct use of `'static` in the substs of `impl2`.
3. Check that all of the generic parameters of `impl1` occur at most once in the *unconstrained* substs for `impl2`. A parameter is constrained if its value is completely determined by an associated type projection predicate.
4. Check that all predicates on `impl1` also exist on `impl2` (after matching substs).
## Example
Suppose we have the following always applicable impl:
```rust
impl<T> SpecExtend<T> for std::vec::IntoIter<T> { /* specialized impl */ }
impl<T, I: Iterator<Item=T>> SpecExtend<T> for I { /* default impl */ }
```
We get that the subst for `impl2` are `[T, std::vec::IntoIter<T>]`. `T` is constrained to be `<I as Iterator>::Item`, so we check only `std::vec::IntoIter<T>` for repeated parameters, which it doesn't have. The predicates of `impl1` are only `T: Sized`, which is also a predicate of impl2`. So this specialization is sound.
## Extensions
Unfortunately not all specializations in the standard library are allowed by this. So there are two extensions to these rules that allow specializing on some traits.
### rustc_specialization_trait
If a trait is always applicable, then it's sound to specialize on it. We check trait is always applicable in the same way as impls, except that step 4 is now "all predicates on `impl1` are always applicable". We require that `specialization` or `min_specialization` is enabled to implement these traits.
### rustc_specialization_marker
There are also some specialization on traits with no methods, including the `FusedIterator` trait which is advertised as allowing optimizations. We allow marking marker traits with an unstable attribute that means we ignore them in point 3 of the checks above. This is unsound but we allow it in the short term because it can't cause use after frees with purely safe code in the same way as specializing on traits methods can.
Dylan DPC [Mon, 16 Mar 2020 12:16:44 +0000 (13:16 +0100)]
Rollup merge of #69989 - petrochenkov:nolegacy, r=eddyb,matthewjasper
resolve/hygiene: `macro_rules` are not "legacy"
The "modern" vs "legacy" naming was introduced by jseyfried during initial implementation of macros 2.0.
At this point it's clear that `macro_rules` are not going anywhere and won't be deprecated in the near future.
So this PR changes the naming "legacy" (when it implies "macro_rules") to "macro_rules".
This should also help people reading this code because it's wasn't obvious that "legacy" actually meant "macro_rules" in these contexts.
The most contentious renaming here is probably
```
fn modern -> fn normalize_to_macros_2_0
fn modern_and_legacy -> fn normalize_to_macro_rules
```
Other alternatives that I could think of are `normalize_to_opaque`/`normalize_to_semitransparent`, or `strip_non_opaque`/`strip_transparent`, but they seemed less intuitive.
The documentation to these functions can be found in `symbol.rs`.
Dylan DPC [Mon, 16 Mar 2020 12:16:35 +0000 (13:16 +0100)]
Rollup merge of #69122 - dtolnay:backtrace, r=cramertj
Backtrace Debug tweaks
- Change Debug representation of disabled and unsupported backtraces to use \<placeholder\> style, same as what we do for debug printing locked mutexes and mutably borrowed refcells;
Dylan DPC [Mon, 16 Mar 2020 12:16:30 +0000 (13:16 +0100)]
Rollup merge of #67335 - ecstatic-morse:qualif-refactor, r=eddyb
Refactor the `Qualif` trait
This PR attempts to preserve the existing semantics of the `Qualif` trait while reducing its API to two significant methods with descriptive names, `in_any_value_of_ty` and `in_adt_inherently`. The other `in_*` methods have been made into free functions, since they should never be overloaded. Finally, I changed the bounds on the `in_local` argument to be less restrictive (`FnMut` instead of `Fn`), which addresses a FIXME in the const-checker.
bors [Mon, 16 Mar 2020 02:52:47 +0000 (02:52 +0000)]
Auto merge of #70034 - Dylan-DPC:rollup-5yg771j, r=Dylan-DPC
Rollup of 8 pull requests
Successful merges:
- #69686 (Use `pprust` to print attributes in rustdoc)
- #69858 (std: on Windows, use GetSystemTimePreciseAsFileTime if it is available)
- #69917 (Cleanup E0412 and E0422)
- #69964 (Add Node.js to PR CI image)
- #69992 (Block version-specific docs from search engines)
- #69995 (Add more context to the literal overflow message)
- #69998 (Add long error explanation for E0634)
- #70014 (Small fixes in rustdoc book)
Dylan DPC [Mon, 16 Mar 2020 00:30:41 +0000 (01:30 +0100)]
Rollup merge of #70014 - TimotheeGerber:small-fix-rustdoc-book, r=Dylan-DPC
Small fixes in rustdoc book
I read the `rustdoc` book today and noticed some small typos/problems. Mainly:
- `# fn foo() {}` was displayed when not needed because fenced block code type was `text` instead of `rust`;
- two path separators were missing and some Windows-style separators were not consistent with the rest of them (mainly Linux-style).
Here are my proposed fixes. It is my first PR for the rust project. Don't hesitate to tell me if I am doing it wrong or if you need anything else.
Dylan DPC [Mon, 16 Mar 2020 00:30:35 +0000 (01:30 +0100)]
Rollup merge of #69992 - kornelski:robots, r=steveklabnik
Block version-specific docs from search engines
Latest stable, beta and nightly URLs remain accessible because their URLs don't start with a version number. Robots.txt uses simple path prefixes, so it's OK that the disallow rules aren't full directory paths.
Direct links to old docs remain accessible to users, because robots.txt only affects crawlers.
With this change old docs for specific old versions of Rust won't pop up in search results. This is good, because users won't be getting obsolete documentation by accident.
I'm not sure what the original motivation was for the `render_attribute`, so I may be missing something, but replacing it with `pprust::attribute_to_string` seems to give the intended output (modulo some spacing idiosyncrasies).
Rollup merge of #69589 - petrochenkov:maccall, r=Centril
ast: `Mac`/`Macro` -> `MacCall`
It's now obvious that these refer to macro calls rather than to macro definitions.
It's also a single name instead of two different names in different places.
`rustc_expand` usually calls macro calls in a wide sense (including attributes and derives) "macro invocations", but structures and variants renamed in this PR are only relevant to fn-like macros, so it's simpler and clearer to just call them calls.
cc https://github.com/rust-lang/rust/pull/63586#discussion_r314232513
r? @eddyb
Rollup merge of #69528 - HeroicKatora:finalize-ref-cell, r=dtolnay
Add undo_leak to reset RefCell borrow state
This method is complementary for the feature cell_leak added in an
earlier PR. It allows *safely* reverting the effects of leaking a borrow guard by
statically proving that such a guard could not longer exist. This was
not added to the existing `get_mut` out of concern of impacting the
complexity of the otherwise pure pointer cast and because the name
`get_mut` poorly communicates the intent of resetting remaining borrows.
This is a follow-up to #68712 and uses the same tracking issue, #69099,
as these methods deal with the same mechanism and the idea came up
[in a review comment](https://github.com/rust-lang/rust/pull/68712#discussion_r384670041).
bors [Sun, 15 Mar 2020 10:52:37 +0000 (10:52 +0000)]
Auto merge of #70016 - Dylan-DPC:rollup-5k7lxs3, r=Dylan-DPC
Rollup of 7 pull requests
Successful merges:
- #69357 (Emit 1-based column numbers in debuginfo)
- #69471 (Remove `sip::Hasher::short_write`.)
- #69498 (Change "method" to "associated function")
- #69967 (Remove a few `Rc`s from RegionInferenceCtxt)
- #69987 (Add self to .mailmap)
- #69991 (fix E0117 message out of sync)
- #69993 (Add long error explanation for E0693)
Dylan DPC [Sun, 15 Mar 2020 01:44:20 +0000 (02:44 +0100)]
Rollup merge of #69987 - kraai:mailmap, r=nikomatsakis
Add self to .mailmap
The variants are only used for [rust-lang/rust-clippy](https://github.com/rust-lang/rust-clippy), but it seems like <https://thanks.rust-lang.org/> only uses this `.mailmap`.
Dylan DPC [Sun, 15 Mar 2020 01:44:17 +0000 (02:44 +0100)]
Rollup merge of #69498 - mark-i-m:describe-it-2, r=matthewjasper
Change "method" to "associated function"
r? @matthewjasper
cc @Centril @eddyb #67742
I'm opening this mostly as a test to see what the diagnostic changes would be. It seems that this makes them somewhat more verbose, and I'm not sure it's worth it...
The relevant changes are the last two commits (it is rebased on top of #67742)
Dylan DPC [Sun, 15 Mar 2020 01:44:15 +0000 (02:44 +0100)]
Rollup merge of #69471 - nnethercote:rm-sip-Hasher-short_write, r=dtolnay
Remove `sip::Hasher::short_write`.
`sip::Hasher::short_write` is currently unused. It is called by
`sip::Hasher::write_{u8,usize}`, but those methods are also unused,
because `DefaultHasher`, `SipHasher` and `SipHasher13` don't implement
any of the `write_xyz` methods, so all their write operations end up
calling `sip::Hasher::write`.
(I confirmed this by inserting a `panic!` in `sip::Hasher::short_write`
and running the tests -- they all passed.)
The alternative would be to add all the missing `write_xyz` methods.
This does give some significant speed-ups, but it hurts compile times a
little in some cases. See #69152 for details. This commit does the
conservative thing and doesn't change existing behaviour.
Dylan DPC [Sun, 15 Mar 2020 01:44:13 +0000 (02:44 +0100)]
Rollup merge of #69357 - tmiasko:debuginfo-column, r=michaelwoerister
Emit 1-based column numbers in debuginfo
* Use byte offsets instead of char position offsets. Resolves #67360.
* Use 1-based offsets instead of 0-based ones. Resolves #65437.
* Consistently omit column information for msvc targets, matching clang behaviour (previously columns have been omitted from `DILocation`, but not from `DILexicalBlock`).
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