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stdio: make stdout block-buffered when not associated to a terminal #148274

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stdio: make stdout block-buffered when not associated to a terminal #148274

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@andreacorbellini andreacorbellini commented Oct 30, 2025

This changes std::io::Stdout so that:

  • it is line-buffered when connected to a terminal
  • it is block-buffered otherwise

This matches the behavior of standard library implementations from other popular languages (C/C++/Python just to name a few).

@rustbot rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Oct 30, 2025
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rustbot commented Oct 30, 2025

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@rustbot rustbot added the O-windows Operating system: Windows label Oct 30, 2025
@andreacorbellini andreacorbellini mentioned this pull request Oct 30, 2025
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andreacorbellini commented Oct 30, 2025

This PR seems to have discovered an interesting bug. Reported at #148278

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the8472 commented Oct 30, 2025

Please see #60673 for prior discussion

@andreacorbellini andreacorbellini marked this pull request as draft November 1, 2025 02:23
@rustbot 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 Nov 1, 2025
@andreacorbellini andreacorbellini mentioned this pull request Nov 1, 2025
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