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Handle same-crate macro for borrowck semicolon suggestion #142584

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Merged
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Jun 17, 2025
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Merged

Handle same-crate macro for borrowck semicolon suggestion #142584

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5 changes: 1 addition & 4 deletions compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -342,10 +342,7 @@ impl<'tcx> BorrowExplanation<'tcx> {
}
}
} else if let LocalInfo::BlockTailTemp(info) = local_decl.local_info() {
let sp = info
.span
.find_ancestor_in_same_ctxt(local_decl.source_info.span)
.unwrap_or(info.span);
let sp = info.span.find_oldest_ancestor_in_same_ctxt();
if info.tail_result_is_ignored {
// #85581: If the first mutable borrow's scope contains
// the second borrow, this suggestion isn't helpful.
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59 changes: 16 additions & 43 deletions tests/ui/borrowck/span-semicolon-issue-139049.fixed
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Original file line number Diff line number Diff line change
@@ -1,52 +1,25 @@
// Make sure the generated suggestion suggest editing the user
// code instead of the std macro implementation
// Make sure the generated suggestion suggest editing the user code instead of
// the macro implementation (which might come from an external crate).
// issue: <https://github.com/rust-lang/rust/issues/139049>

//@ run-rustfix

#![allow(dead_code)]

use std::fmt::{self, Display};

struct Mutex;

impl Mutex {
fn lock(&self) -> MutexGuard<'_> {
MutexGuard(self)
}
}

struct MutexGuard<'a>(&'a Mutex);

impl<'a> Drop for MutexGuard<'a> {
fn drop(&mut self) {}
}

struct Out;

impl Out {
fn write_fmt(&self, _args: fmt::Arguments) {}
}

impl<'a> Display for MutexGuard<'a> {
fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result {
Ok(())
}
}
// You could assume that this comes from an extern crate (it doesn't
// because an aux crate would be overkill for this test).
macro_rules! perform { ($e:expr) => { D(&$e).end() } }
//~^ ERROR does not live long enough
//~| ERROR does not live long enough

fn main() {
let _write = {
let mutex = Mutex;
write!(Out, "{}", mutex.lock());
//~^ ERROR `mutex` does not live long enough
//~| SUGGESTION ;
};

let _write = {
use std::io::Write as _;
{ let l = (); perform!(l); };
//~^ SUGGESTION ;

let mutex = Mutex;
let x = write!(std::io::stdout(), "{}", mutex.lock()); x
//~^ ERROR `mutex` does not live long enough
//~| SUGGESTION let x
};
let _x = { let l = (); let x = perform!(l); x };
//~^ SUGGESTION let x
}

struct D<T>(T);
impl<T> Drop for D<T> { fn drop(&mut self) {} }
impl<T> D<T> { fn end(&self) -> String { String::new() } }
59 changes: 16 additions & 43 deletions tests/ui/borrowck/span-semicolon-issue-139049.rs
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Original file line number Diff line number Diff line change
@@ -1,52 +1,25 @@
// Make sure the generated suggestion suggest editing the user
// code instead of the std macro implementation
// Make sure the generated suggestion suggest editing the user code instead of
// the macro implementation (which might come from an external crate).
// issue: <https://github.com/rust-lang/rust/issues/139049>

//@ run-rustfix

#![allow(dead_code)]

use std::fmt::{self, Display};

struct Mutex;

impl Mutex {
fn lock(&self) -> MutexGuard<'_> {
MutexGuard(self)
}
}

struct MutexGuard<'a>(&'a Mutex);

impl<'a> Drop for MutexGuard<'a> {
fn drop(&mut self) {}
}

struct Out;

impl Out {
fn write_fmt(&self, _args: fmt::Arguments) {}
}

impl<'a> Display for MutexGuard<'a> {
fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result {
Ok(())
}
}
// You could assume that this comes from an extern crate (it doesn't
// because an aux crate would be overkill for this test).
macro_rules! perform { ($e:expr) => { D(&$e).end() } }
//~^ ERROR does not live long enough
//~| ERROR does not live long enough

fn main() {
let _write = {
let mutex = Mutex;
write!(Out, "{}", mutex.lock())
//~^ ERROR `mutex` does not live long enough
//~| SUGGESTION ;
};

let _write = {
use std::io::Write as _;
{ let l = (); perform!(l) };
//~^ SUGGESTION ;

let mutex = Mutex;
write!(std::io::stdout(), "{}", mutex.lock())
//~^ ERROR `mutex` does not live long enough
//~| SUGGESTION let x
};
let _x = { let l = (); perform!(l) };
//~^ SUGGESTION let x
}

struct D<T>(T);
impl<T> Drop for D<T> { fn drop(&mut self) {} }
impl<T> D<T> { fn end(&self) -> String { String::new() } }
62 changes: 32 additions & 30 deletions tests/ui/borrowck/span-semicolon-issue-139049.stderr
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Original file line number Diff line number Diff line change
@@ -1,46 +1,48 @@
error[E0597]: `mutex` does not live long enough
--> $DIR/span-semicolon-issue-139049.rs:39:27
error[E0597]: `l` does not live long enough
--> $DIR/span-semicolon-issue-139049.rs:11:41
|
LL | let mutex = Mutex;
| ----- binding `mutex` declared here
LL | write!(Out, "{}", mutex.lock())
| ^^^^^-------
| |
| borrowed value does not live long enough
| a temporary with access to the borrow is created here ...
LL | macro_rules! perform { ($e:expr) => { D(&$e).end() } }
| --^^^-
| | |
| | borrowed value does not live long enough
| a temporary with access to the borrow is created here ...
...
LL | };
| -- ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `MutexGuard`
| |
| `mutex` dropped here while still borrowed
LL | { let l = (); perform!(l) };
| - ----------- -- ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `D`
| | | |
| | | `l` dropped here while still borrowed
| | in this macro invocation
| binding `l` declared here
|
= note: this error originates in the macro `perform` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider adding semicolon after the expression so its temporaries are dropped sooner, before the local variables declared by the block are dropped
|
LL | write!(Out, "{}", mutex.lock());
| +
LL | { let l = (); perform!(l); };
| +

error[E0597]: `mutex` does not live long enough
--> $DIR/span-semicolon-issue-139049.rs:48:41
error[E0597]: `l` does not live long enough
--> $DIR/span-semicolon-issue-139049.rs:11:41
|
LL | let mutex = Mutex;
| ----- binding `mutex` declared here
LL | write!(std::io::stdout(), "{}", mutex.lock())
| ^^^^^-------
| |
| borrowed value does not live long enough
| a temporary with access to the borrow is created here ...
LL | macro_rules! perform { ($e:expr) => { D(&$e).end() } }
| --^^^-
| | |
| | borrowed value does not live long enough
| a temporary with access to the borrow is created here ...
...
LL | };
| -- ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `MutexGuard`
| |
| `mutex` dropped here while still borrowed
LL | let _x = { let l = (); perform!(l) };
| - ----------- -- ... and the borrow might be used here, when that temporary is dropped and runs the `Drop` code for type `D`
| | | |
| | | `l` dropped here while still borrowed
| | in this macro invocation
| binding `l` declared here
|
= note: the temporary is part of an expression at the end of a block;
consider forcing this temporary to be dropped sooner, before the block's local variables are dropped
= note: this error originates in the macro `perform` (in Nightly builds, run with -Z macro-backtrace for more info)
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
|
LL | let x = write!(std::io::stdout(), "{}", mutex.lock()); x
| +++++++ +++
LL | let _x = { let l = (); let x = perform!(l); x };
| +++++++ +++

error: aborting due to 2 previous errors

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