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Minor tweaks to refcell logging #142216

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Minor tweaks to refcell logging #142216

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20 changes: 14 additions & 6 deletions library/core/src/cell.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -743,7 +743,7 @@ impl Debug for BorrowError {
let mut builder = f.debug_struct("BorrowError");

#[cfg(feature = "debug_refcell")]
builder.field("location", self.location);
builder.field("location", &format_args!("{}", self.location));

builder.finish()
}
Expand All @@ -770,7 +770,7 @@ impl Debug for BorrowMutError {
let mut builder = f.debug_struct("BorrowMutError");

#[cfg(feature = "debug_refcell")]
builder.field("location", self.location);
builder.field("location", &format_args!("{}", self.location));

builder.finish()
}
Expand All @@ -787,16 +787,24 @@ impl Display for BorrowMutError {
#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
#[track_caller]
#[cold]
fn panic_already_borrowed(err: BorrowMutError) -> ! {
panic!("already borrowed: {:?}", err)
fn panic_already_borrowed(_err: BorrowMutError) -> ! {
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Small nit, this can be _err -> err since it is used

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_err is used in one code path (when debug_refcell is enabled) but not the other, the reason being is that when debug_refcell is disabled, BorrowError/BorrowMutError are empty structs.

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Right, but whether or not something gets used on all branches doesn't affect liveliness - one is enough. It would be different if the comptime #[cfg(...)] was used rather than the runtime cfg!() (semantically runtime at least, even though it's gone with the most basic optimizations) but there won't be any dead_code warnings here.

if cfg!(feature = "debug_refcell") {
panic!("cannot borrow as mutable because it is also borrowed as immutable here {:?}", _err);
} else {
panic!("cannot borrow as mutable because it is also borrowed as immutable");
}
}

// This ensures the panicking code is outlined from `borrow` for `RefCell`.
#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
#[track_caller]
#[cold]
fn panic_already_mutably_borrowed(err: BorrowError) -> ! {
panic!("already mutably borrowed: {:?}", err)
fn panic_already_mutably_borrowed(_err: BorrowError) -> ! {
if cfg!(feature = "debug_refcell") {
panic!("cannot borrow as immutable because it is also borrowed as mutable here {:?}", _err);
} else {
panic!("cannot borrow as immutable because it is also borrowed as mutable");
}
}

// Positive values represent the number of `Ref` active. Negative values
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