In CTFE heavy code, checking the env var everytime is inefficient. We
can do a lot better by using a `Session` variable instead.

Changed functions:
* LLVMRustGetOrInsertFunction
* LLVMRustGetNamedValue
* LLVMRustBuildCall (removed unused name argument)
* LLVMRustInlineAsm
* LLVMRustInlineAsmVerify
* LLVMRustAppendModuleInlineAsm

…r=ollie27

--show-coverage json

The purpose of this change is to be able to use it as a tool in docs.rs in order to provide some more stats to crates' owners. Eventually even create a badge or something along the line.

r? @QuietMisdreavus

…etrochenkov

tidy: replace `make check` with `./x.py test` in documentation

This PR includes a minor documentation update for tidy.  It replaces the `make check` approach with `./x.py test` and describes how to execute the tidy checks (only) with ~~`./x.py test src/tools/tidy`~~ `./x.py test tidy`.

Improve expression & attribute parsing

This PR includes misc improvements to expression and attribute parsing.

1. Some code simplifications
2. Better recovery for various block forms, e.g. `loop statements }` (missing `{` after `loop`). (See e.g., `block-no-opening-brace.rs` among others for examples.)
3. Added recovery for e.g., `unsafe $b` where `$b` refers to a `block` macro fragment. (See `bad-interpolated-block.rs` for examples.)
4. ^--- These are done so that code sharing in block parsing is increased.
5. Added recovery for e.g., `'label: loop { ... }` (See `labeled-no-colon-expr.rs`.)
6. Added recovery for e.g., `&'lifetime expr` (See `regions-out-of-scope-slice.rs`.)
7. Added recovery for e.g., `fn foo() = expr;` (See `fn-body-eq-expr-semi.rs`.)
8. Simplified attribute parsing code & slightly improved diagnostics.
9. Added recovery for e.g., `Box<('a) + Trait>`.
10. Added recovery for e.g, `if true #[attr] {} else #[attr] {} else #[attr] if true {}`.

r? @estebank

fix memory leak when vec::IntoIter panics during drop

Fixes rust-lang#69770

panic_bounds_check: use caller_location, like PanicFnLangItem

The `PanicFnLangItem` got switched to using `#[caller_location]` at some point, but `PanicBoundsCheckFnLangItem` was kept in the old style. For consistency, switch that one over to use `#[caller_location]` as well.

This is also helpful for Miri as it means the `assert_panic` machine hook never needs to know the current `Span`.

…error-code-e0739, r=Dylan-DPC

Add long error explanation for E0739

Add long explanation for the E0739 error code
Part of rust-lang#61137

r? @GuillaumeGomez

…to_session_var, r=RalfJung

[Miri] Use a session variable instead of checking for an env var always

In CTFE heavy code, checking the env var everytime is inefficient. We
can do a lot better by using a `Session` variable instead.

r? @RalfJung

Part of rust-lang#69297

librustc_codegen_llvm: Use slices instead of 0-terminated strings

Changed functions:
* LLVMRustGetOrInsertFunction
* LLVMRustGetNamedValue
* LLVMRustBuildCall (removed unused name argument)
* LLVMRustInlineAsm
* LLVMRustInlineAsmVerify
* LLVMRustAppendModuleInlineAsm