Inline read_{un,}signed_leb128 and opaque::Decoder functions.
`read_unsigned_leb128` is hot within rustc because it's heavily used
during the reading of crate metadata. This commit tweaks its signature
(and that of `read_signed_leb128`, for consistency) so it can increment
the buffer index directly instead of maintaining its own copy, the
change in which is then used by the caller to advance the index.
This reduces the instruction count (as measured by Cachegrind) for some
benchmarks a bit, e.g. hyper-0.5.0 by 0.7%.
Clarify the positions of the lexer and parser
The lexer and parser use unclear names to indicate their positions in the
source code. I propose the following renamings.
Lexer:
```
pos -> next_pos # it's actually the next pos!
last_pos -> pos # it's actually the current pos!
curr -> ch # the current char
curr_is -> ch_is # tests the current char
col (unchanged) # the current column
```
parser
```
- last_span -> prev_span # the previous token's span
- last_token_kind -> prev_token_kind # the previous token's kind
- LastTokenKind -> PrevTokenKind # ditto (but the type)
- token (unchanged) # the current token
- span (unchanged) # the current span
```
Things to note:
- This proposal removes all uses of "last", which is an unclear word because it
could mean (a) previous, (b) final, or (c) most recent, i.e. current.
- The "current" things (ch, col, token, span) consistently lack a prefix. The
"previous" and "next" things consistently have a prefix.
Update comment in Vec::dedup_by
It's a tiny thing, but I came across this comment which previously was in `dedup` and wasn't updated when `dedup_by` was introduced.
include LLVM version in `--version --verbose`
This is in the matter of #28405.
```
$ ./x86_64-unknown-linux-gnu/stage1/bin/rustc --version --verbose
rustc 1.14.0-dev (8e05e7ee3 2016-10-15)
binary: rustc
commit-hash: 8e05e7ee3c
commit-date: 2016-10-15
host: x86_64-unknown-linux-gnu
release: 1.14.0-dev
LLVM version: 3.9
```
debuginfo: Remove some outdated stuff from LLVM DIBuilder binding.
These seem to be leftovers from various adaptations to changes in LLVM over time.
Perfect for a rollup.
r? @eddyb
Use a distinct error code for "if may be missing an else clause"
Introduce the possibility of assigning distinct error codes to the various origin types of E0308. Start by assigning E0317 for the "IfExpressionWithNoElse" case, and write a long diagnostic specific to this case.
Fixes#36596
debuginfo: Handle spread_arg case in MIR-trans in a more stable way.
Use `VariableAccess::DirectVariable` instead of `VariableAccess::IndirectVariable` in order not to make LLVM's SROA angry. This is a step towards fixing #36774 and #35547. At least, I can build Cargo with optimizations + debuginfo again.
r? @eddyb
normalize types every time HR regions are erased
Associated type normalization is inhibited by higher-ranked regions.
Therefore, every time we erase them, we must re-normalize.
I was meaning to introduce this change some time ago, but we used
to erase regions in generic context, which broke this terribly (because
you can't always normalize in a generic context). That seems to be gone
now.
Ensure this by having a `erase_late_bound_regions_and_normalize`
function.
Fixes#37109 (the missing call was in mir::block).
r? @eddyb
rustdoc: Improve playground run buttons
The main change is to stop using javascript to generate the URLs and use
rustdoc instead.
This also adds run buttons to the error index examples.
You can test the changes at https://ollie27.github.io/rust_doc_test/.
Fixes#36621Fixes#36910
add a per-param-env cache to `impls_bound`
There used to be only a global cache, which led to uncached calls to
trait selection when there were type parameters.
This causes a 20% decrease in borrow-checking time and an overall 0.5% performance increase during bootstrapping (as borrow-checking tends to be a tiny part of compilation time).
Fixes#37106 (drop elaboration times are now ~half of borrow checking,
so might still be worthy of optimization, but not critical).
r? @pnkfelix
Change Substs to type alias for Slice<Kind> for interning
This changes the definition of `librustc::ty::subst::Substs` to be a type alias to `Slice<Kind>`. `Substs` was already interned, but can now make use of the efficient `PartialEq` and `Hash` impls on `librustc::ty::Slice`.
I'm working on collecting some timing data for this, will update when it's done.
I chose to leave the impls on `Substs<'tcx>` even though it's now just a type alias to `Slice<Kind<'tcx>>` because it has the smallest footprint on other portions of the compiler which depend on its API. It turns out to be a pretty huge diff if you change where Substs's methods live 😄. That said, I'm not necessarily sure it's the *best* implementation but it's probably the easiest/smallest to review.
Many thanks to @eddyb for both suggesting this as a project for learning more about the compiler, and the tireless ~~handholding~~ mentorship he provided.
Specialize Vec::extend to Vec::extend_from_slice
I tried using the existing `SpecExtend` as a helper trait for this, but the instances would always conflict with the instances higher up in the file, so I created a new helper trait.
Benchmarking `extend` vs `extend_from_slice` with an slice of 1000 `u64`s gives the following results:
```
before:
running 2 tests
test tests::bench_extend_from_slice ... bench: 166 ns/iter (+/- 78)
test tests::bench_extend_trait ... bench: 1,187 ns/iter (+/- 697)
after:
running 2 tests
test tests::bench_extend_from_slice ... bench: 149 ns/iter (+/- 87)
test tests::bench_extend_trait ... bench: 138 ns/iter (+/- 70)
```
Implement `read_offset` and `write_offset`
These functions allow to read from and write to a file from multiple
threads without changing the per-file cursor, avoiding the race between
the seek and the read.
add (missing) tar to list of packages to get under mingw
The distribution targets use tar, but the readme pacman invocation doesn't include the tar package.
Explain motivation behind lifetimes
Start the lifetime section with an explanation of the issues that lack of explicit lifetimes cause and how the explicit lifetimes solve these.
----------------
I had really hard time figuring out why I would need to care about the explicit reference lifetimes when going through the book at first. With strong background in C++, I'm familiar with the dangling reference problem - but given the section seems to focus more on the lifetime syntax and various ways to define lifetimes on functions and structs, I was unable to understand how they are used to solve the reference problem.
This PR is an attempt at getting the reader to understand what the explicit lifetimes are used for and why they are an awesome thing instead of a bit of syntax that just has to be written.
It's been less than a week that I've been diving into Rust so I'm far from certain about the terminology and technical correctness. I tried mimicking the existing terminology from the lifetimes section, but still no promises on getting it right.
Changed error message E0408 to new format
Followed your text and was able to change the ouput to the new format.
I did not encounter any broken test therefore this is a really small commit.
Thanks for letting me hack on the compiler :)
r? @jonathandturner
