`write_metadata` currently generates metadata unnecessarily in some
cases, and also compresses it unnecessarily in some cases. This commit
fixes that. It speeds up three of the rustc-benchmarks by 1--4%.
This will make it easier for packagers to bootstrap rustc when they happen
to have a bootstrap compiler with a slightly different version number.
It's not ok for anything other than the build system to set this environment variable.
The example code for higher-ranked trait bounds on closures had an
unnecessary `mut` which was confusing, and the text referred to an
mutable reference which does not exist in the code (and isn't needed).
Removed the `mut`s and fixed the text to better describe the actual
error for the failing example.
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.
This commit guards all calls to `DepGraphThreadData::enqueue` with a
check to make sure it is enabled. This requires distinguishing between a
"fully enabled" and an "enqueue-enabled" graph.
This change avoids some useless allocation and vector manipulations when
the graph is disabled (i.e. when incremental compilation is off) which
improves speed by ~1% on some of the rustc-benchmarks.
In #34268 (8531d581), we replaced matches of None to the unit value `()`
with `if let`s in places where it was deemed that this made the code
unambiguously clearer and more idiomatic. In #34638 (d37edef9), we did
the same for matches of None to the empty block `{}`.
A casual observer, upon seeing these commits fly by, might suppose that
the matter was then settled, that no further pull requests on this
utterly trivial point of style could or would be made. Unless ...
It turns out that sometimes people write the empty block with a space in
between the braces. Who knew?
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
This is overdue, even if range and RangeArgument is still unstable.
The stability attributes are the same ones as the other unstable item
(Bound) here, they don't seem to matter.
This addresses issue pointed out by niko that prior code would break
if the declaration order for generics does not match how they are fed
into the instantiation of the type itself. (Added some tests
exercising this scenario.)
We can't use more than usize's bits of a hash to select a bucket anyway,
so we only need to store that part in the table. This should be an
improvement for the size of the data structure on 32-bit platforms.
Smaller data means better cache utilization and hopefully better
performance.
Implement .zip() specialization for Map and Cloned.
The crucial thing for transparent specialization is that we want to
preserve the potential side effects.
The simplest example is that in this code snippet:
`(0..6).map(f).zip((0..4).map(g)).count()`
`f` will be called five times, and `g` four times. The last time for `f`
is when the other iterator is at its end, so this element is unused.
This side effect can be preserved without disturbing code generation for
simple uses of `.map()`.
The `Zip::next_back()` case is even more complicated, unfortunately.
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
The original sentence is:
> This example has two conversions: `Rc<String>` to `String` and then `String` to `&str`.
But it should be
> This example has two conversions: `Rc<String>` to `String` and then `String` to `str`.
or
> This example has two conversions: `&Rc<String>` to `&String` and then `&String` to `&str`.
I think the latter is more clearly.
