1.96 beta regression: "`lua` does not live long enough"

[theemathas]

Regression found by the 1.95 beta crater "rerun", done to check whether #154074 (which got backported to beta in #154725) causes any regressions. (This PR was initially done to fix #153850.)

[INFO] [stdout] error[E0597]: `lua` does not live long enough
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/shulkerscript-0.1.0/src/transpile/lua.rs:51:30
[INFO] [stdout]    |
[INFO] [stdout] 18 |         #[tracing::instrument(level = "debug", name = "eval_lua", skip_all, ret)]
[INFO] [stdout]    |                                                                                 - ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `(LuaValue<'_>,)`
[INFO] [stdout] ...
[INFO] [stdout] 25 |             let lua = Lua::new();
[INFO] [stdout]    |                 --- binding `lua` declared here
[INFO] [stdout] ...
[INFO] [stdout] 51 |             let lua_result = lua
[INFO] [stdout]    |                              ^^^ borrowed value does not live long enough
[INFO] [stdout] ...
[INFO] [stdout] 62 |             self.handle_lua_result(dbg!(lua_result)).map_err(|err| {
[INFO] [stdout]    |                                    ---------------- a temporary with access to the borrow is created here ...
[INFO] [stdout] ...
[INFO] [stdout] 66 |         }
[INFO] [stdout]    |         - `lua` dropped here while still borrowed
[INFO] [stdout]    |
[INFO] [stdout]    = note: the temporary is part of an expression at the end of a block;
[INFO] [stdout]            consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
[INFO] [stdout] help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block
[INFO] [stdout]    |
[INFO] [stdout] 62 ~             let x = self.handle_lua_result(dbg!(lua_result)).map_err(|err| {
[INFO] [stdout] 63 |                 handler.receive(err.clone());
[INFO] [stdout] 64 |                 err
[INFO] [stdout] 65 ~             }); x
[INFO] [stdout]    |

• https://crater-reports.s3.amazonaws.com/beta-1.95-4/1.95.0-beta.7/reg/shulkerscript-0.1.0/log.txt
• https://crater-reports.s3.amazonaws.com/beta-1.95-4/1.95.0-beta.7/reg/shulkerscript-cli-0.1.0/log.txt (dependent of above crate)

cc @dianne

[theemathas]

Minimized (requires edition 2021, not 2024):

#[derive(Debug)]
struct Foo;

#[derive(Debug)]
struct Bar<'a>(&'a Foo);
impl Drop for Bar<'_> {
    fn drop(&mut self) {}
}

fn main() {
    let foo = Foo;
    let bar = Bar(&foo);
    drop(dbg!(bar))  // No semicolon
}

Error output on beta:

error[E0597]: `foo` does not live long enough
  --> src/main.rs:12:19
   |
11 |     let foo = Foo;
   |         --- binding `foo` declared here
12 |     let bar = Bar(&foo);
   |                   ^^^^ borrowed value does not live long enough
13 |     drop(dbg!(bar))  // No semicolon
   |          --------- a temporary with access to the borrow is created here ...
14 | }
   | -
   | |
   | `foo` dropped here while still borrowed
   | ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `(Bar<'_>,)`
   |
help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
   |
13 |     drop(dbg!(bar));  // No semicolon
   |                    +

For more information about this error, try `rustc --explain E0597`.