Determining this path occasionally fails locally for unknown reasons, resulting
in the build failing with an unhelpful `StripPrefixError(())` panic message.

In order to track down why that's happening, include some relevant information
in the panic message when that failure occurs.

We recently had an issue because some rustlib files were missing (like: "error[E0463]: can't find crate for rustc_ast")
when building tools that rely on rustc. This patch fixes that by copying those files as required.

Signed-off-by: onur-ozkan <[email protected]>

... can not be correctly gated using #[cfg] macro

Signed-off-by: onur-ozkan <[email protected]>

…llot

Add an internal lint that warns when accessing untracked data

Some methods access data that is not tracked by the query system and should be used with caution. As suggested in rust-lang#128815 (comment), in this PR I propose a lint (modeled on the `potential_query_instability` lint) that warns when using some specially-annotatted functions.

I can't tell myself if this lint would be that useful, compared to renaming `Steal::is_stolen` to `is_stolen_untracked`. This would depend on whether there are other functions we'd want to lint like this. So far it seems they're called `*_untracked`, which may be clear enough.

r? `@oli-obk`

…m-const, r=lcnr

fix ICE when `asm_const` and `const_refs_to_static` are combined

fixes rust-lang#129462
fixes rust-lang#126896
fixes rust-lang#124164

I think this is a case that was missed in the fix for rust-lang#125558, which inserts a type error in the case of an invalid (that is, non-integer) type being passed to an asm `const` operand.

I'm not 100% sure that `span_mirbug_and_err` is the right macro here, but it is used earlier with `builtin_deref` and seems to do the trick.

r? `@lcnr`

…tmcm

clarify that addr_of creates read-only pointers

Stacked Borrows does make this UB, but Tree Borrows does not. This is tied up with rust-lang#56604 and other UCG discussions. Also see [this collection of links](Rust-for-Linux/linux#950 (comment)) where rustc treats `addr_of!` as a "non-mutating use".

So, let's better be careful for now.

…arsan68

bootstrap: Try to track down why `initial_libdir` sometimes fails

When I try to run `x` commands from the command-line, I occasionally see a mysterious failure that looks something like this:

```text
thread 'main' panicked at src/lib.rs:341:14:
called `Result::unwrap()` on an `Err` value: StripPrefixError(())
```

It happens often enough to be annoying, but rarely enough that I can't reproduce it at will. The error message points to a particular `unwrap` call, but doesn't include enough context to determine *why* the failure occurs.

Re-running the command almost always works, so I suspect some kind of filesystem race condition (possibly involving VSCode invoking bootstrap at the same time), but there's not much I can do with the information I currently have.

So this PR includes some relevant information in the panic message when the failure occurs, in the hope that doing so will make the cause easier to track down when the failure occurs again.

…rors

explain why Rvalue::Len still exists

I just spent a bit of time trying to remove this until I realized why that's non-trivial. Let's document that for the next person. :)

…RalfJung

s390x: Fix a regression related to backchain feature

In rust-lang#127506, we introduced a new IBM Z-specific target feature, `backchain`.

This particular `target-feature` was available as a function-level attribute in LLVM 17 and below, so some hacks were used to avoid blowing up LLVM when querying the supported LLVM features.

This led to an unfortunate regression where `cfg!(target-feature = "backchain")` will always return true.

This pull request aims to fix this issue, and a test has been introduced to ensure it will never happen again.

Fixes rust-lang#129927.

r? `@RalfJung`

…=Kobzol

copy rustc rustlib artifacts from ci-rustc

We recently (since rust-lang#129311) had an issue because some rustlib files were missing (like: "error[E0463]: can't find crate for rustc_ast") when building tools that rely on rustc. This patch fixes that by copying those files as required.

r? Kobzol

Blocker for rust-lang#122709

…er, r=Kobzol

use the bootstrapped compiler for `test-float-parse` test

Fixes rust-lang#122709 (comment).

Blocker for rust-lang#122709

…pietroalbini

Add compat note for trait solver change

r? `@pietroalbini` `@BoxyUwU`

cc `@lcnr`

…separators, r=tgross35

Add digit separators in `Duration` examples

`@rustbot` label A-docs

Temporarily remove fmease from the review rotation

Namely for like a week. I seriously need to work off my review backlog!

r? fmease

…bertlarsan68

forward linker option to lint-docs

This fixes an error found when building the doc for a cross-built toolchain.

```
warning: the code example in lint `unstable_syntax_pre_expansion` in /buildroots/chenx97/rustc-1.80.1-src/compiler/rustc_lint_defs/src/builtin.rs failed to generate the expected output: did not find lint `unstable_syntax_p
re_expansion` in output of example, got:

error: linking with `cc` failed: exit status: 1
...
```
Closes: rust-lang#129956