LLDB's expression parser can't unambiguously resolve local variables in
some cases, as described in rust-lang#47938. Work around this by using names that
don't shadow direct submodules of `core`.

Rustbuild usually writes the LLVM submodule commit in a stamp file, so
we can avoid rebuilding it unnecessarily. However, for builds from a
source tarball (non-git), we were assuming a rebuild is always needed.
This can cause a lot of extra work if any environment like `CFLAGS`
changed between steps like build and install, which are often separate
in distro builds.

Now we also write an empty stamp file if the git commit is unknown, and
its presence is trusted to indicate that no rebuild is needed. An info
message reports that this is happening, along with the stamp file path
that can be deleted to force a rebuild anyway.

Also document `ast::Pat::walk`.

Fuse `parse_top_pat` and `parse_top_pat_unpack` into just `parse_top_pat`.

Introduces a temporary hack to keep `Vec<P<Pat>>` in
`hir::Arm.pats` so that we keep the changes more incremental.

Previously the build would take the presence of the LLVM_CONFIG envvar to
mean that the sanitizers should be built, but this is a common envvar that
could be set for reasons unrelated to the rustc sanitizers.

This commit adds a new envvar RUSTC_BUILD_SANITIZERS and uses it instead.

This commit rejiggers the generics used in the implementation of
`Command::env` with the purpose of reducing the amount of codegen that
needs to happen in consumer crates, instead preferring to generate code
into libstd.

This was found when profiling the compile times of the `cc` crate where
the binary rlib produced had a lot of `BTreeMap` code compiled into it
but the crate doesn't actually use `BTreeMap`. It turns out that
`Command::env` is generic enough to codegen the entire implementation in
calling crates, but in this case there's no performance concern so it's
fine to compile the code into the standard library.

This change is done by removing the generic on the `CommandEnv` map
which is intended to handle case-insensitive variables on Windows.
Instead now a generic isn't used but rather a `use` statement defined
per-platform is used.

With this commit a debug build of `Command::new("foo").env("a", "b")`
drops from 21k lines of LLVM IR to 10k.

We publish this to crates.io, so having non-empty meta is useful

Fuchsia provides a fully monotonic clock.

Use wasi crate for Core API

Blocked by: bytecodealliance/wasi-rs#5

Blocks: rust-lang/libc#1461

cc @sunfishcode @alexcrichton

Update libc to 0.2.62

Hopefully this will mitigate rust-lang/libc#1489 and rust-lang#64006

…050, r=alexcrichton

Rename test locals to work around LLDB bug

LLDB's expression parser can't unambiguously resolve local variables in
some cases, as described in rust-lang#47938. Work around this by using names that
don't shadow direct submodules of `core`.

Closes rust-lang#64050.

…umeGomez

Improve searching in rustdoc and add tests

👋 I have made searching in rustdoc more intuitive, added a couple more tests and made a little shell script to aid testing. Closes rust-lang#63005.

It took me quite a while to figure out how to run the tests for rustdoc (instead of running tests for other crates with rustdoc); the only pointer I found was [hidden in the rustc book](https://rust-lang.github.io/rustc-guide/rustdoc.html#cheat-sheet). Maybe this could be better documented? I shall be delighted to help if it is desirable.

…ark-Simulacrum

Fix regex replacement in theme detection

Fixes rust-lang#64061.

This is sadly a lot of bad luck: after making the changes and re-build the docs, I just forgot to force reload the page. Hence having the old (working) version with two replacements instead of the failing regex. Sorry again about that...

cc @fenhl
r? @Mark-Simulacrum

…ochenkov

or-patterns: Uniformly use `PatKind::Or` in AST & Fix/Cleanup resolve

Following up on work in rust-lang#63693 and rust-lang#61708, in this PR we:

- Uniformly use `PatKind::Or(...)` in AST:

   - Change `ast::Arm.pats: Vec<P<Pat>>` => `ast::Arm.pat: P<Pat>`

   - Change `ast::ExprKind::Let.0: Vec<P<Pat>>` => `ast::ExprKind::Let.0: P<Pat>`

- Adjust `librustc_resolve/late.rs` to correctly handle or-patterns at any level of nesting as a result.

  In particular, the already-bound check which rejects e.g. `let (a, a);` now accounts for or-patterns. The consistency checking (ensures no missing bindings and binding mode consistency) also now accounts for or-patterns. In the process, a bug was found in the current compiler which allowed:

   ```rust
   enum E<T> { A(T, T), B(T) }
   use E::*;
   fn foo() {
       match A(0, 1) {
           B(mut a) | A(mut a, mut a) => {}
       }
   }
   ```

   The new algorithms took a few iterations to get right. I tried several clever schemes but ultimately a version based on a stack of hashsets and recording product/sum contexts was chosen since it is more clearly correct.

- Clean up `librustc_resolve/late.rs` by, among other things, using a new `with_rib` function to better ensure stack dicipline.

- Do not push the change in AST to HIR for now to avoid doing too much in this PR. To cope with  this, we introduce a temporary hack in `rustc::hir::lowering` (clearly marked in the diff).

cc rust-lang#54883
cc @dlrobertson @matthewjasper
r? @petrochenkov

Assume non-git LLVM is fresh if the stamp file exists

Rustbuild usually writes the LLVM submodule commit in a stamp file, so
we can avoid rebuilding it unnecessarily. However, for builds from a
source tarball (non-git), we were assuming a rebuild is always needed.
This can cause a lot of extra work if any environment like `CFLAGS`
changed between steps like build and install, which are often separate
in distro builds.

Now we also write an empty stamp file if the git commit is unknown, and
its presence is trusted to indicate that no rebuild is needed. An info
message reports that this is happening, along with the stamp file path
that can be deleted to force a rebuild anyway.

Fixes rust-lang#61206.

Better way of conditioning the sanitizer builds

Previously the build would take the presence of the LLVM_CONFIG envvar to
mean that the sanitizers should be built, but this is a common envvar that
could be set for reasons unrelated to the rustc sanitizers.

This commit adds a new envvar RUSTC_BUILD_SANITIZERS and uses it instead.

This PR or similar will be necessary in order to work correctly with rust-lang/compiler-builtins#296

Update Clippy

Closes rust-lang#64163
r? @oli-obk @Manishearth

…-should-be-div, r=Mark-Simulacrum

Fix invalid span generation when it should be div

Fixes rust-lang#64146.

It changes basically nothing in the display... Can be checked with:

```rust
pub enum X {
    /// Some doc?
    ///
    /// with lines!
    Foo {
        /// a
        ///
        /// b
        x: u32,
        /// Doc!
        ///
        /// ```
        /// yolo
        /// ```
        y: String,
    },
    /// Doc!
    ///
    /// ```
    /// yolo
    /// ```
    Bar(String),
}
```

r? @Mark-Simulacrum

…=sfackler

std: Improve downstream codegen in `Command::env`

This commit rejiggers the generics used in the implementation of
`Command::env` with the purpose of reducing the amount of codegen that
needs to happen in consumer crates, instead preferring to generate code
into libstd.

This was found when profiling the compile times of the `cc` crate where
the binary rlib produced had a lot of `BTreeMap` code compiled into it
but the crate doesn't actually use `BTreeMap`. It turns out that
`Command::env` is generic enough to codegen the entire implementation in
calling crates, but in this case there's no performance concern so it's
fine to compile the code into the standard library.

This change is done by removing the generic on the `CommandEnv` map
which is intended to handle case-insensitive variables on Windows.
Instead now a generic isn't used but rather a `use` statement defined
per-platform is used.

With this commit a debug build of `Command::new("foo").env("a", "b")`
drops from 21k lines of LLVM IR to 10k.

fill metadata in rustc_lexer's Cargo.toml

We publish this to crates.io, so having non-empty meta is useful

…richton

Add Fuchsia to actually_monotonic

Fuchsia provides a fully monotonic clock.

Fix rust-lang#64196

cc @joshlf @tmandry

r? @alexcrichton