In e4b1a79 (#47922), we corrected erroneous suggestions for unused
shorthand field pattern bindings, suggesting `field: _` where the
previous suggestion of `_field` wouldn't even have compiled
(#47390). Soon, it was revealed that this was insufficient (#50303), and
the fix was extended to references, slices, &c. (#50327) But even this
proved inadequate, as the erroneous suggestions were still being issued
for patterns in local (`let`) bindings (#50804). Here, we yank the
shorthand-detection and variable/node registration code into a new
common function that can be called while visiting both match arms and
`let` bindings.
Resolves#50804.
This turns an ICE on this code:
fn main() {
|_: [u8; break]| ();
}
from
'assertion failed: self.tcx.sess.err_count() > 0', librustc_typeck/check/mod.rs
to
librustc_mir/hair/cx/expr.rs:543: invalid loop id for break: not inside loop scope
which is at a later stage during compilation and most importantly
fixes of bug #50576 will fix this as well.
stop considering location when computing outlives relationships
This doesn't (yet?) use SEME regions, but it does ignore the location for outlives constraints. This makes (I believe) NLL significantly faster -- but we should do some benchmarks. It regresses the "get-default" family of use cases for NLL, which is a shame, but keeps the other benefits, and thus represents a decent step forward.
r? @pnkfelix
This used to be disabled due to LLVM bugs in the handling of
noalias information in conjunction with unwinding. However,
according to #31681 all known LLVM bugs have been fixed by
LLVM 6.0, so it's probably time to reenable this optimization.
Noalias annotations will not be emitted by default if either
-C panic=abort (as previously) or LLVM >= 6.0 (new).
-Z mutable-noalias=no is left as an escape-hatch to allow
debugging problems suspected to stem from this change.
Keep only the language item. This removes some indirection and makes
codegen worse for debug builds, but simplifies code significantly, which
is a good tradeoff to make, in my opinion.
Besides, the codegen can be improved even further with some constant
evaluation improvements that we expect to happen in the future.
Make sure people know the book is free oline
I've used the tutorial a number of times to relearn rust basics. When i saw this for a moment I was sad thinking it had been taken offline.
Speed up `opt_normalize_projection_type`
`opt_normalize_projection_type` is hot in the serde and futures benchmarks in rustc-perf. These two patches speed up the execution of most runs for them by 2--4%.
Fix null exclusions in grammar docs
The grammar documentation incorrectly says that comments, character literals,
and string literals may not include null.
Fix grammar documentation wrt Unicode identifiers
The grammar defines identifiers in terms of XID_start and XID_continue,
but this is referring to the unstable non_ascii_idents feature.
The documentation implies that non_ascii_idents is forthcoming, but this
is left over from pre-1.0 documentation; in reality, non_ascii_idents
has been without even an RFC for several years now, and will not be
stabilized anytime soon. Furthermore, according to the tracking issue at
https://github.com/rust-lang/rust/issues/28979 , it's highly
questionable whether or not this feature will use XID_start or
XID_continue even when or if non_ascii_idents is stabilized.
This commit fixes this by respecifying identifiers as the usual
[a-zA-Z_][a-zA-Z0-9_]*
Tweak `nearest_common_ancestor()`.
- Remove the "no nearest common ancestor found" case, because it's never
hit in practise. (This means `closure_is_enclosed_by` can also be
removed.)
- Add a comment about why `SmallVec` is used for the "seen" structures.
- Use `&Scope` instead of `Scope` to avoid some `map()` calls.
- Use `any(p)` instead of `position(p).is_some()`.
r? @nikomatsakis
Improve format string errors
Point at format string position inside the formatting string:
```
error: invalid format string: unmatched `}` found
--> $DIR/format-string-error.rs:21:22
|
LL | let _ = format!("}");
| ^ unmatched `}` in format string
```
Explain that argument names can't start with an underscore:
```
error: invalid format string: invalid argument name `_foo`
--> $DIR/format-string-error.rs:15:23
|
LL | let _ = format!("{_foo}", _foo = 6usize);
| ^^^^ invalid argument name in format string
|
= note: argument names cannot start with an underscore
```
Fix#23476.
The more accurate spans will only be seen when using `format!` directly, when using `println!` the diagnostics machinery makes the span be the entire statement.
This is necessary if we want to implement `[T]::align_to` and is more
useful in general.
This implementation effort has begun during the All Hands and represents
a month of my futile efforts to do any sort of maths. Luckily, I
found the very very nice Chris McDonald (cjm) on IRC who figured out the
core formulas for me! All the thanks for existence of this PR go to
them!
Anyway… Those formulas were mangled by yours truly into the arcane forms
you see here to squeeze out the best assembly possible on most of the
modern architectures (x86 and ARM were evaluated in practice). I mean,
just look at it: *one actual* modulo operation and everything else is
just the cheap single cycle ops! Admitedly, the naive solution might be
faster in some common scenarios, but this code absolutely butchers the
naive solution on the worst case scenario.
Alas, the result of this arcane magic also means that the code pretty
heavily relies on the preconditions holding true and breaking those
preconditions will unleash the UB-est of all UBs! So don’t.
