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Rollup merge of #101690 - kadiwa4:avoid_iterator_last, r=oli-obk

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Avoid `Iterator::last`

Adapters like `Filter` and `Map` use the default implementation of `Iterator::last` which is not short-circuiting (and so does `core::str::Split`). The predicate function will be run for every single item of the underlying iterator. I hope that removing those calls to `last` results in slight performance improvements.
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Dylan DPC 2022-09-13 16:51:31 +05:30 • committed by GitHub
commit d5b86d5ee9
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7 changed files with 11 additions and 15 deletions
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6
compiler/rustc_session/src/session.rs
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@ -1309,10 +1309,8 @@ pub fn build_session(
let warnings_allow = sopts
.lint_opts
.iter()
.filter(|&&(ref key, _)| *key == "warnings")
.map(|&(_, ref level)| *level == lint::Allow)
.last()
.unwrap_or(false);
.rfind(|&&(ref key, _)| *key == "warnings")
.map_or(false, |&(_, level)| level == lint::Allow);
let cap_lints_allow = sopts.lint_cap.map_or(false, |cap| cap == lint::Allow);
let can_emit_warnings = !(warnings_allow || cap_lints_allow);