std: make `OsString::truncate` a no-op when `len > current_len` by xtqqczze · Pull Request #152998 · rust-lang/rust

xtqqczze · 2026-02-23T01:48:52Z

Align OsString::truncate (and the underlying WTF-8 implementation) with String::truncate by making it a no-op when len > self.len().

Previously, OsString::truncate would panic if len > self.len(), while String::truncate treats such cases as a no-op.

Tracking (os_string_truncate): #133262
See also: #32977

cc: @alexcrichton, @lolbinarycat

rustbot · 2026-02-23T01:48:56Z

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library/alloc/src/wtf8/mod.rs

Align `OsString::truncate` (and the underlying WTF-8 implementation) with `String::truncate` by making it a no-op when `len > self.len()`. Previously, `OsString::truncate` would panic if `len > self.len()`, while `String::truncate` treats such cases as a no-op.

jhpratt · 2026-03-01T21:25:30Z

This seems reasonable, but has it been discussed anywhere?

lolbinarycat · 2026-03-03T18:06:43Z

I don't think it was discussed anywhere to my knowledge, maybe in the original implementation PR?

Parity seems like a good idea, but should we ask t-libs-api for confirmation?

jhpratt · 2026-03-04T00:30:32Z

cc @rust-lang/libs-api; given that it's unstable I'm not sure what procedure is here.

asder8215 · 2026-03-04T01:16:37Z

Parity seems like a good idea, but should we ask t-libs-api for confirmation?

Yea, I would defer this to lib-api to make the call.

Amanieu

This is reasonable and makes it consistent with every other truncate method in the standard library.

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jhpratt · 2026-03-17T07:38:58Z

@bors r+ rollup

rust-bors · 2026-03-17T07:39:02Z

📌 Commit 3ecd18c has been approved by jhpratt

It is now in the queue for this repository.

@alexcrichton

std: make `OsString::truncate` a no-op when `len > current_len` Align `OsString::truncate` (and the underlying WTF-8 implementation) with `String::truncate` by making it a no-op when `len > self.len()`. Previously, `OsString::truncate` would panic if `len > self.len()`, while `String::truncate` treats such cases as a no-op. Tracking (`os_string_truncate`): #133262 See also: #32977 cc: @alexcrichton, @lolbinarycat

rust-bors · 2026-03-17T10:48:49Z

💔 Test for 57a5ee9 failed: CI. Failed job:

auto - aarch64-gnu-debug (web logs, enhanced plaintext logs)

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The job aarch64-gnu-debug failed! Check out the build log: (web) (plain enhanced) (plain)

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[1906/5488] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/LiveRangeCalc.cpp.o
[1907/5488] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/LiveIntervalCalc.cpp.o
[1908/5488] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/LiveRangeEdit.cpp.o

Session terminated, killing shell...::group::Clock drift check
##[error]The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
  local time: Tue Mar 17 10:48:06 UTC 2026
  network time: [1909/5488] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/LiveRangeShrink.cpp.o
[1910/5488] Building CXX object lib/CodeGen/CMakeFiles/LLVMCodeGen.dir/LiveRegMatrix.cpp.o
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Tue, 17 Mar 2026 10:48:06 GMT

JonathanBrouwer · 2026-03-17T20:19:03Z

@bors retry
Spurious

…uwer Rollup of 6 pull requests Successful merges: - #152998 (std: make `OsString::truncate` a no-op when `len > current_len`) - #153682 (Tweak E0599 note) - #153795 (Point turbofish inference errors at the uninferred generic arg) - #153994 (move `tests/ui/invalid` tests to new folders) - #154006 (attrs: Ignore ExprKind::Err when converting path attr expr to lit) - #154012 (unstable impl of `From<{i64, u64}> for f128`)

rustbot assigned jhpratt Feb 23, 2026

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xtqqczze force-pushed the panic-truncate branch from 9be1130 to 3c790ce Compare February 23, 2026 01:58

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xtqqczze force-pushed the panic-truncate branch from 3c790ce to 14f592a Compare February 23, 2026 02:41

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xtqqczze force-pushed the panic-truncate branch from 14f592a to 768010a Compare February 23, 2026 11:16

xtqqczze marked this pull request as draft February 23, 2026 11:16

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Feb 23, 2026

xtqqczze marked this pull request as ready for review February 23, 2026 13:25

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asder8215 reviewed Feb 24, 2026

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library/alloc/src/wtf8/mod.rs Outdated Show resolved Hide resolved

xtqqczze force-pushed the panic-truncate branch from 768010a to 294a7e2 Compare February 27, 2026 18:45

xtqqczze changed the title ~~std: make OsString::truncate a no-op when len >= current_len~~ std: make OsString::truncate a no-op when len > current_len Feb 27, 2026

xtqqczze force-pushed the panic-truncate branch from 294a7e2 to 3ecd18c Compare February 27, 2026 18:49

Amanieu approved these changes Mar 6, 2026

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JonathanBrouwer mentioned this pull request Mar 17, 2026

Rollup of 6 pull requests #154013

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rust-bors bot merged commit b1050a7 into rust-lang:main Mar 18, 2026
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rustbot added this to the 1.96.0 milestone Mar 18, 2026

xtqqczze deleted the panic-truncate branch March 18, 2026 02:42

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