…ifetimes, r=lcnr

Enforce tail call type is related to body return type in borrowck

Like all call terminators, tail call terminators instantiate the binder of the callee signature with region variables and equate the arg operand types with that signature's args to ensure that the call is valid.

However, unlike normal call terminators, we were forgetting to also relate the return type of the call terminator to anything. In the case of tail call terminators, the correct thing is to relate it to the return type of the caller function (or in other words, the return local `_0`).

This meant that if the caller's return type had some lifetime constraint, then that constraint wouldn't flow through the signature and affect the args.

This is what's happening in the example test I committed:

```rust
fn link(x: &str) -> &'static str {
    become passthrough(x);
}

fn passthrough<T>(t: T) -> T { t }

fn main() {
    let x = String::from("hello, world");
    let s = link(&x);
    drop(x);
    println!("{s}");
}
```

Specifically, the type `x` is `'?0 str`, where `'?0` is some *universal* arg. The type of `passthrough` is `fn(&'?1 str) -> &'?1 str`. Equating the args sets `'?0 = '?1`. However, we need to also equate the return type `&'?1 str` to `&'static str` so that we eventually require that `'?0 = 'static`, which is a borrowck error!

-----

Look at the first commit for the functional change, and the second commit is just a refactor because we don't need to pass `Option<BasicBlock>` to `check_call_dest`, but just whether or not the terminator is expected to be diverging (i.e. if the return type is `!`).

Fixes rust-lang#144916

…ifetimes, r=lcnr

Enforce tail call type is related to body return type in borrowck

Like all call terminators, tail call terminators instantiate the binder of the callee signature with region variables and equate the arg operand types with that signature's args to ensure that the call is valid.

However, unlike normal call terminators, we were forgetting to also relate the return type of the call terminator to anything. In the case of tail call terminators, the correct thing is to relate it to the return type of the caller function (or in other words, the return local `_0`).

This meant that if the caller's return type had some lifetime constraint, then that constraint wouldn't flow through the signature and affect the args.

This is what's happening in the example test I committed:

```rust
fn link(x: &str) -> &'static str {
    become passthrough(x);
}

fn passthrough<T>(t: T) -> T { t }

fn main() {
    let x = String::from("hello, world");
    let s = link(&x);
    drop(x);
    println!("{s}");
}
```

Specifically, the type `x` is `'?0 str`, where `'?0` is some *universal* arg. The type of `passthrough` is `fn(&'?1 str) -> &'?1 str`. Equating the args sets `'?0 = '?1`. However, we need to also equate the return type `&'?1 str` to `&'static str` so that we eventually require that `'?0 = 'static`, which is a borrowck error!

-----

Look at the first commit for the functional change, and the second commit is just a refactor because we don't need to pass `Option<BasicBlock>` to `check_call_dest`, but just whether or not the terminator is expected to be diverging (i.e. if the return type is `!`).

Fixes rust-lang#144916

Rollup of 11 pull requests

Successful merges:

 - #143857 (Port #[macro_export] to the new attribute parsing infrastructure)
 - #144133 (Stabilize const TypeId::of)
 - #144676 (Add documentation for unstable_feature_bound)
 - #144682 (Stabilize `strict_overflow_ops`)
 - #144835 (Anonymize binders in tail call sig)
 - #144836 (Change visibility of Args new function)
 - #144900 (Stabilize `unsigned_signed_diff` feature)
 - #144917 (Enforce tail call type is related to body return type in borrowck)
 - #144926 (Correct the use of `must_use` on btree::IterMut)
 - #144928 (Drop `rust-version` from `rustc_thread_pool`)
 - #144945 (Autolabel PRs that change explicit tail call tests as `F-explicit_tail_calls`)

r? `@ghost`
`@rustbot` modify labels: rollup

Rollup of 11 pull requests

Successful merges:

 - #143857 (Port #[macro_export] to the new attribute parsing infrastructure)
 - #144133 (Stabilize const TypeId::of)
 - #144676 (Add documentation for unstable_feature_bound)
 - #144682 (Stabilize `strict_overflow_ops`)
 - #144835 (Anonymize binders in tail call sig)
 - #144836 (Change visibility of Args new function)
 - #144900 (Stabilize `unsigned_signed_diff` feature)
 - #144917 (Enforce tail call type is related to body return type in borrowck)
 - #144926 (Correct the use of `must_use` on btree::IterMut)
 - #144928 (Drop `rust-version` from `rustc_thread_pool`)
 - #144945 (Autolabel PRs that change explicit tail call tests as `F-explicit_tail_calls`)

r? `@ghost`
`@rustbot` modify labels: rollup

Rollup of 11 pull requests

Successful merges:

 - #143857 (Port #[macro_export] to the new attribute parsing infrastructure)
 - #144133 (Stabilize const TypeId::of)
 - #144676 (Add documentation for unstable_feature_bound)
 - #144682 (Stabilize `strict_overflow_ops`)
 - #144835 (Anonymize binders in tail call sig)
 - #144836 (Change visibility of Args new function)
 - #144900 (Stabilize `unsigned_signed_diff` feature)
 - #144917 (Enforce tail call type is related to body return type in borrowck)
 - #144926 (Correct the use of `must_use` on btree::IterMut)
 - #144928 (Drop `rust-version` from `rustc_thread_pool`)
 - #144945 (Autolabel PRs that change explicit tail call tests as `F-explicit_tail_calls`)

r? `@ghost`
`@rustbot` modify labels: rollup

…ifetimes, r=lcnr

Enforce tail call type is related to body return type in borrowck

Like all call terminators, tail call terminators instantiate the binder of the callee signature with region variables and equate the arg operand types with that signature's args to ensure that the call is valid.

However, unlike normal call terminators, we were forgetting to also relate the return type of the call terminator to anything. In the case of tail call terminators, the correct thing is to relate it to the return type of the caller function (or in other words, the return local `_0`).

This meant that if the caller's return type had some lifetime constraint, then that constraint wouldn't flow through the signature and affect the args.

This is what's happening in the example test I committed:

```rust
fn link(x: &str) -> &'static str {
    become passthrough(x);
}

fn passthrough<T>(t: T) -> T { t }

fn main() {
    let x = String::from("hello, world");
    let s = link(&x);
    drop(x);
    println!("{s}");
}
```

Specifically, the type `x` is `'?0 str`, where `'?0` is some *universal* arg. The type of `passthrough` is `fn(&'?1 str) -> &'?1 str`. Equating the args sets `'?0 = '?1`. However, we need to also equate the return type `&'?1 str` to `&'static str` so that we eventually require that `'?0 = 'static`, which is a borrowck error!

-----

Look at the first commit for the functional change, and the second commit is just a refactor because we don't need to pass `Option<BasicBlock>` to `check_call_dest`, but just whether or not the terminator is expected to be diverging (i.e. if the return type is `!`).

Fixes rust-lang#144916

Rollup of 21 pull requests

Successful merges:

 - #137831 (Tweak auto trait errors)
 - #138689 (add nvptx_target_feature)
 - #140267 (implement continue_ok and break_ok for ControlFlow)
 - #143679 (Preserve the .debug_gdb_scripts section)
 - #143857 (Port #[macro_export] to the new attribute parsing infrastructure)
 - #143929 (Mark all deprecation lints in name resolution as deny-by-default and report-in-deps)
 - #144133 (Stabilize const TypeId::of)
 - #144369 (Upgrade semicolon_in_expressions_from_macros from warn to deny)
 - #144473 (Address libunwind.a inconsistency issues in the bootstrap program)
 - #144498 (Add --print target-spec-json-schema)
 - #144552 (Rehome 33 `tests/ui/issues/` tests to other subdirectories under `tests/ui/`)
 - #144659 (bootstrap: refactor mingw dist and fix gnullvm)
 - #144676 (Add documentation for unstable_feature_bound)
 - #144794 (Port `#[coroutine]` to the new attribute system)
 - #144835 (Anonymize binders in tail call sig)
 - #144836 (Change visibility of Args new function)
 - #144861 (Stabilize `panic_payload_as_str` feature)
 - #144910 (Add regression tests for seemingly fixed issues)
 - #144913 ([rustdoc] Fix wrong `i` tooltip icon)
 - #144917 (Enforce tail call type is related to body return type in borrowck)
 - #144924 (compiletest: add hint for when a ui test produces no errors)

r? `@ghost`
`@rustbot` modify labels: rollup

Rollup of 15 pull requests

Successful merges:

 - #144195 (Parser: Recover from attributes applied to types and generic args)
 - #144794 (Port `#[coroutine]` to the new attribute system)
 - #144835 (Anonymize binders in tail call sig)
 - #144861 (Stabilize `panic_payload_as_str` feature)
 - #144917 (Enforce tail call type is related to body return type in borrowck)
 - #144948 (we only merge candidates for trait and normalizes-to goals)
 - #144956 (Gate const trait syntax)
 - #144970 (rustdoc: fix caching of intra-doc links on reexports)
 - #144972 (add code example showing that file_prefix treats dotfiles as the name of a file, not an extension)
 - #144975 (`File::set_times`: Update documentation and example to support setting timestamps on directories)
 - #144977 (Fortify generic param default checks)
 - #144996 (simplifycfg: Mark as changed when start is modified in collapse goto chain)
 - #144998 (mir: Do not modify NonUse in `super_projection_elem`)
 - #145000 (Remove unneeded `stage` parameter when setting up stdlib Cargo)
 - #145008 (Fix rustdoc scrape examples crash)

r? `@ghost`
`@rustbot` modify labels: rollup

Rollup merge of #144917 - compiler-errors:tail-call-linked-lifetimes, r=lcnr

Enforce tail call type is related to body return type in borrowck

Like all call terminators, tail call terminators instantiate the binder of the callee signature with region variables and equate the arg operand types with that signature's args to ensure that the call is valid.

However, unlike normal call terminators, we were forgetting to also relate the return type of the call terminator to anything. In the case of tail call terminators, the correct thing is to relate it to the return type of the caller function (or in other words, the return local `_0`).

This meant that if the caller's return type had some lifetime constraint, then that constraint wouldn't flow through the signature and affect the args.

This is what's happening in the example test I committed:

```rust
fn link(x: &str) -> &'static str {
    become passthrough(x);
}

fn passthrough<T>(t: T) -> T { t }

fn main() {
    let x = String::from("hello, world");
    let s = link(&x);
    drop(x);
    println!("{s}");
}
```

Specifically, the type `x` is `'?0 str`, where `'?0` is some *universal* arg. The type of `passthrough` is `fn(&'?1 str) -> &'?1 str`. Equating the args sets `'?0 = '?1`. However, we need to also equate the return type `&'?1 str` to `&'static str` so that we eventually require that `'?0 = 'static`, which is a borrowck error!

-----

Look at the first commit for the functional change, and the second commit is just a refactor because we don't need to pass `Option<BasicBlock>` to `check_call_dest`, but just whether or not the terminator is expected to be diverging (i.e. if the return type is `!`).

Fixes #144916