Make Duration respect width when formatting using Debug
#88999
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Duration's Debug formatting previously ignored the width parameter. This commit fixes that. Fixes issue rust-lang#88059.
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Duration handle width when formatting using DebugDuration respect width when formatting using Debug
Considering the fact that booleans are also default-left-aligned, that seems like a safe choice. We can wait for someone with strong opinions on this to give us a reason to change it. @bors r+ Thanks! I just ran into such oddities earlier this week, and you're already fixing this one, great! |
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Make `Duration` respect `width` when formatting using `Debug` When printing or writing a `std::time::Duration` using `Debug` formatting, it previously completely ignored any specified `width`. This is unlike types like integers and floats, which do pad to `width`, for both `Display` and `Debug`, though not all types consider `width` in their `Debug` output (see e.g. rust-lang#30164). Curiously, `Duration`'s `Debug` formatting *did* consider `precision`. This PR makes `Duration` pad to `width` just like integers and floats, so that ```rust format!("|{:8?}|", Duration::from_millis(1234)) ``` returns ``` |1.234s | ``` Before you ask "who formats `Debug` output?", note that `Duration` doesn't actually implement `Display`, so `Debug` is currently the only way to format `Duration`s. I think that's wrong, and `Duration` should get a `Display` implementation, but in the meantime there's no harm in making the `Debug` formatting respect `width` rather than ignore it. I chose the default alignment to be left-aligned. The general rule Rust uses is: numeric types are right-aligned by default, non-numeric types left-aligned. It wasn't clear to me whether `Duration` is a numeric type or not. The fact that a formatted `Duration` can end with suffixes of variable length (`"s"`, `"ms"`, `"µs"`, etc.) made me lean towards left-alignment, but it would be trivial to change it. Fixes issue rust-lang#88059.
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⌛ Testing commit 77ceb2b with merge 94ebf7000eb7eb645ced41792cdc1f83c0d7b7af... |
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💔 Test failed - checks-actions |
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I don't understand what went wrong. Looks like the build was cancelled? |
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@bors retry sometimes bors has hickups |
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☀️ Test successful - checks-actions |
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Finished benchmarking commit (f06f9bb): comparison url. Summary: This change led to moderate relevant improvements 🎉 in compiler performance.
If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf. @rustbot label: -perf-regression |
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When printing or writing a
std::time::DurationusingDebugformatting, it previously completely ignored any specifiedwidth. This is unlike types like integers and floats, which do pad towidth, for bothDisplayandDebug, though not all types considerwidthin theirDebugoutput (see e.g. #30164). Curiously,Duration'sDebugformatting did considerprecision.This PR makes
Durationpad towidthjust like integers and floats, so thatreturns
Before you ask "who formats
Debugoutput?", note thatDurationdoesn't actually implementDisplay, soDebugis currently the only way to formatDurations. I think that's wrong, andDurationshould get aDisplayimplementation, but in the meantime there's no harm in making theDebugformatting respectwidthrather than ignore it.I chose the default alignment to be left-aligned. The general rule Rust uses is: numeric types are right-aligned by default, non-numeric types left-aligned. It wasn't clear to me whether
Durationis a numeric type or not. The fact that a formattedDurationcan end with suffixes of variable length ("s","ms","µs", etc.) made me lean towards left-alignment, but it would be trivial to change it.Fixes issue #88059.