`fn resolve_legacy_scope` can now resolve only to `macro_rules!` items,
`fn resolve_lexical_macro_path_segment` is for everything else - modularized macros, preludes
The Great Generics Generalisation: HIR Followup
Addresses the final comments in #48149.
r? @eddyb, but there are a few things I have yet to clean up. Making the PR now to more easily see when things break.
cc @yodaldevoid
Add the identity function as core::convert::identity
## New notes
This implements rust-lang/rfcs#2306 (see https://github.com/rust-lang/rust/issues/53500).
## Old notes (ignore this in new reviews)
Adds the identity function `fn id<T>(x: T) -> T { x }` to core::convert and the prelude.
Some motivations for why this is useful are explained in the doc tests.
Another is that using the identity function instead of `{ x }` or `|x| x` makes it clear that you intended to use an identity conversion on purpose.
The reasoning:
+ behind adding this to `convert` and not `mem` is that this is an identity *conversion*.
+ for adding this to the prelude is that it should be easy enough to use that the ease of writing your own identity function or using a closure `|x| x` doesn't overtake that.
I've separated this out into two feature gates so that the addition to the prelude can be considered and stabilized separately.
cc @bluss
52985: cause cycle err on inf trait normalization
Issue: #52985
- If an existential type is defined, but no user code infers the
concrete type behind the existential type, normalization would
infinitely recurse on this existential type which is only defined in
terms of itself.
- Instead of raising an inf recurse error, we cause a cycle error to
help highlight that the issue is that the type is only defined in terms
of itself.
- Three known potential improvements:
- If type folding itself was exposed as a query, used by
normalization and other mechanisms, cases that would cause infinite recursion would
automatically cause a cycle error.
- The span for the cycle error should be improved to point to user
code that fails to allow inference of the concrete type of the existential type,
assuming that this error occurs because no user code can allow inference the
concrete type.
- A mechanism to extend the cycle error with a helpful note would be nice. Currently,
the error is built and maintained by src/librustc/ty/query/plumbing,
with no known way to extend the information that the error gets built
with.
r? @oli-obk
optimize reassignment immutable state
This is the "simple fix" when it comes to checking for reassignment. We just shoot for compatibility with the AST-based checker. Makes no attempt to solve #21232.
I opted for this simpler fix because I didn't want to think about complications [like the ones described here](https://github.com/rust-lang/rust/issues/21232#issuecomment-412219247).
Let's do some profiling measurements.
Fixes#53189
r? @pnkfelix
[NLL] Returns are interesting for free regions
Based on #53088 - creating now to get feedback.
Closes#51175
* Make assigning to the return type interesting.
* Use "returning this value" instead of "return" in error messages.
* Prefer one of the explanations that we have a name for to a generic interesting cause in some cases.
* Treat causes that involve the destination of a call like assignments.
Make some ported cfail tests robust w.r.t. NLL
Updated the most glaring instances of weak tests w.r.t. NLL that came from #53196.
See also the bulletpoint list on #53351.
Rollup of 11 pull requests
Successful merges:
- #52858 (Implement Iterator::size_hint for Elaborator.)
- #53321 (Fix usage of `wasm_target_feature`)
- #53326 ([nll] add regression test for issue #27868)
- #53347 (rustc_resolve: don't allow paths starting with `::crate`.)
- #53349 ([nll] add tests for #48697 and #30104)
- #53357 (Pretty print btreemap for GDB)
- #53358 (`{to,from}_{ne,le,be}_bytes` for unsigned integer types)
- #53406 (Do not suggest conversion method that is already there)
- #53407 (make more ported compile fail tests more robust w.r.t. NLL)
- #53413 (Warn that `#![feature(rust_2018_preview)]` is implied when the edition is set to Rust 2018.)
- #53434 (wasm: Remove --strip-debug argument to LLD)
Failed merges:
r? @ghost
make more ported compile fail tests more robust w.r.t. NLL
This is similar to PR #53369, except it covers a disjoint (and much smaller) set of tests that I needed to look at more carefully before being 100% certain they were the same kind of issue.
[nll] add tests for #48697 and #30104
Adds tests for the following issues:
- #48697 ``[NLL] ICE: unexpected region for local data with reference to closure``
- #30104 ``Destructuring boxes into multiple mutable references seems broken``
r? @nikomatsakis
[nll] add regression test for issue #27868
Adds a test for #27868 ``Inconsistent evaluation order for assignment operations``
apart of #47366 ``tracking issue for bugs fixed by the MIR borrow checker or NLL``
r? @nikomatsakis
compile-fail-fulldeps/proc-macro/proc-macro-attributes.rs - resolution change for derive helper attributes with the same name as derive itself
run-pass/macro-comma-support.rs - indeterminate resolutions for macros in expression positions
ui/issues/issue-49074.rs - diagnostics regression, not enough recovery to report the second error
ui/object-lifetime/object-lifetime-default.stderr - unstable diagnostics?
