Rollup merge of #87052 - phlopsi:patch-1, r=jyn514
Optimize fmt::PadAdapter::wrap After adding the first `write!` usage to my project and printing the result to the console, I noticed, that my binary contains the strings "called `Option::unwrap()` on a `None` value`" and more importantly "C:\Users\Patrick Fischer\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\fmt\builders.rs", with my release build being configured as follows: ``` [profile.release] panic = "abort" codegen-units = 1 strip = "symbols" # the important bit lto = true ``` I am in a no_std environment and my custom panic handler is a simple `loop {}`. I did not expect the above information to be preserved. I heavily suspect the edited function to be the culprit. It contains the only direct use of `Option::unwrap` in the entire file and I tracked the symbols in the assembly to be used from the section `_ZN68_$LT$core..fmt..builders..PadAdapter$u20$as$u20$core..fmt..Write$GT$9write_str17ha1d5e5efe167202aE`. Aside from me suspecting this function to be the culprit, the replaced code performs the same operation as `Option::insert`, but without the `unreachable_unchecked` optimization `Option::insert` provides. Therefore, it makes sense to me to use the more optimized version, instead. As I don't change any semantics, I hope a simple pull request suffices.
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commit
c25b979db6
1 changed files with 1 additions and 4 deletions
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@ -23,10 +23,7 @@ impl<'buf, 'state> PadAdapter<'buf, 'state> {
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slot: &'slot mut Option<Self>,
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state: &'state mut PadAdapterState,
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) -> fmt::Formatter<'slot> {
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fmt.wrap_buf(move |buf| {
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*slot = Some(PadAdapter { buf, state });
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slot.as_mut().unwrap()
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})
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fmt.wrap_buf(move |buf| slot.insert(PadAdapter { buf, state }))
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}
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}
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