Just like the original article our Windows TLS support is based on predicted,
this symbol must be linked in on MSVC to pull in the necessary support for TLS
variables. This commit fixes a number of unit tests which require that TLS
destructors are run.
This commit alters the compiler to no longer "just run link.exe" but instead
probe the system's registry to find where the linker is located. The default
library search path (normally found through LIB) is also found through the
registry. This also brings us in line with the default behavior of Clang, and
much of the logic of where to look for information is copied over from Clang as
well. Finally, this commit removes the makefile logic for updating the
environment variables for the compiler, except for stage0 where it's still
necessary.
The motivation for this change is rooted in two positions:
* Not having to set up these environment variables is much less hassle both for
the bootstrap and for running the compiler itself. This means that the
compiler can be run outside of VS shells and be run inside of cmd.exe or a
MSYS shell.
* When dealing with cross compilation, there's not actually a set of environment
variables that can be set for the compiler. This means, for example, if a
Cargo compilation is targeting 32-bit from 64-bit you can't actually set up
one set of environment variables. Having the compiler deal with the logic
instead is generally much more convenient!
This commit turns on landing pads for MSVC by default, which means that we'll
now be running cleanups for values on the stack when an exception is thrown.
This commit "fixes" the previously seen LLVM abort by attaching the `noinline`
attribute to all generated drop glue to prevent landing pads from being inlined
into other landing pads.
The performance of MSVC is highly likely to decrease from this commit, but there
are various routes we can taken in the future if this ends up staying for quite
a while, such as generating a shim function only called from landing pads which
calls the actual drop glue, and this shim is marked noinline.
For now, however, this patch enables MSVC to successfully bootstrap itself!
Fixes#26646.
Loops over all `#[repr(..)]` attributes instead of stopping at the first one to make sure they are all marked as used. Previously it stopped after the first `#[repr(C)]` was found causing all other attributes to be skipped by the linter.
fmt: Update docs and mention :#? pretty-printing
Expose `:#?` well in the docs for fmt and Debug itself. Also update some out of date information and fix formatting in `std::fmt` docs.
Update substring search to use the Two Way algorithm
To improve our substring search performance, revive the two way searcher
and adapt it to the Pattern API.
Fixes#25483, a performance bug: that particular case now completes faster
in optimized rust than in ruby (but they share the same order of magnitude).
Many thanks to @gereeter who helped me understand the reverse case
better and wrote the comment explaining `next_back` in the code.
I had quickcheck to fuzz test forward and reverse searching thoroughly.
The two way searcher implements both forward and reverse search,
but not double ended search. The forward and reverse parts of the two
way searcher are completely independent.
The two way searcher algorithm has very small, constant space overhead,
requiring no dynamic allocation. Our implementation is relatively fast,
especially due to the `byteset` addition to the algorithm, which speeds
up many no-match cases.
A bad case for the two way algorithm is:
```
let haystack = (0..10_000).map(|_| "dac").collect::<String>();
let needle = (0..100).map(|_| "bac").collect::<String>());
```
For this particular case, two way is not much faster than the naive
implementation it replaces.
This was originally motivated by checking for HRTB hygiene, but I found several other bugs on the way.
This does not fix the biggest user of ty_walk, which is dtorck - I would prefer to coordinate that with @pnkfelix.
r? @eddyb
This fixes two false positives for the unconditional recursion lint, when functions use themselves (or almost-themselves) internally, without actually being recursive.
````rust
fn main() { let _ = main; }
```
```rust
trait Bar {
fn method<T: Bar>(&self, x: &T) {
x.method(x)
}
}
```
This catches the case when a trait defines a default method that calls
itself, but on a type that isn't necessarily `Self`, e.g. there's no
reason that `T = Self` in the following, so the call isn't necessarily
recursive (`T` may override the call).
trait Bar {
fn method<T: Bar>(&self, x: &T) {
x.method(x)
}
}
Fixes#26333.
