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Rollup merge of #109318 - joboet:better_fmt_placeholder, r=dtolnay

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Make `Debug` representations of `[Lazy, Once]*[Cell, Lock]` consistent with `Mutex` and `RwLock`

`Mutex` prints `<locked>` as a field value when its inner value cannot be accessed, but the lazy types print a fixed string like "`OnceCell(Uninit)`". This could cause confusion if the inner type is a unit type named `Uninit` and does not respect the pretty-printing flag. With this change, the format message is now "`OnceCell(<uninit>)`", consistent with `Mutex`.
This commit is contained in:
Matthias Krüger
2023-07-31 22:51:12 +02:00
committed by GitHub
parent b3df56a65f b7e68dfc94
commit bcfa49f162
6 changed files with 22 additions and 38 deletions
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8
library/std/src/sync/lazy_lock.rs
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@@ -222,10 +222,12 @@ impl<T: Default> Default for LazyLock<T> {
#[unstable(feature = "lazy_cell", issue = "109736")]
impl<T: fmt::Debug, F> fmt::Debug for LazyLock<T, F> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut d = f.debug_tuple("LazyLock");
match self.get() {
Some(v) => f.debug_tuple("LazyLock").field(v).finish(),
None => f.write_str("LazyLock(Uninit)"),
}
Some(v) => d.field(v),
None => d.field(&format_args!("<uninit>")),
};
d.finish()
}
}

8
library/std/src/sync/mutex.rs
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@@ -490,13 +490,7 @@ impl<T: ?Sized + fmt::Debug> fmt::Debug for Mutex<T> {
d.field("data", &&**err.get_ref());
}
Err(TryLockError::WouldBlock) => {
struct LockedPlaceholder;
impl fmt::Debug for LockedPlaceholder {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("<locked>")
}
}
d.field("data", &LockedPlaceholder);
d.field("data", &format_args!("<locked>"));
}
}
d.field("poisoned", &self.poison.get());

8
library/std/src/sync/once_lock.rs
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@@ -365,10 +365,12 @@ impl<T> Default for OnceLock<T> {
#[stable(feature = "once_cell", since = "1.70.0")]
impl<T: fmt::Debug> fmt::Debug for OnceLock<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut d = f.debug_tuple("OnceLock");
match self.get() {
Some(v) => f.debug_tuple("Once").field(v).finish(),
None => f.write_str("Once(Uninit)"),
}
Some(v) => d.field(v),
None => d.field(&format_args!("<uninit>")),
};
d.finish()
}
}

8
library/std/src/sync/rwlock.rs
View File

@@ -485,13 +485,7 @@ impl<T: ?Sized + fmt::Debug> fmt::Debug for RwLock<T> {
d.field("data", &&**err.get_ref());
}
Err(TryLockError::WouldBlock) => {
struct LockedPlaceholder;
impl fmt::Debug for LockedPlaceholder {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("<locked>")
}
}
d.field("data", &LockedPlaceholder);
d.field("data", &format_args!("<locked>"));
}
}
d.field("poisoned", &self.poison.get());