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Mark several functions as noexcept. - #1937

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Stephan T. Lavavej (StephanTLavavej) merged 16 commits into
microsoft:mainfrom
ThomasFWise:more_noexcepts
Aug 18, 2022
Merged

Mark several functions as noexcept.#1937
Stephan T. Lavavej (StephanTLavavej) merged 16 commits into
microsoft:mainfrom
ThomasFWise:more_noexcepts

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@ThomasFWise

@ThomasFWise Thomas Wise (ThomasFWise) commented May 27, 2021 •
edited by strega-nil-ms
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This can be important for performance on x86 when calling these functions from code that is marked noexcept.

Drive by: fix optional::operator CMP to correctly only expect an implicit conversion to bool; example fail: https://gcc.godbolt.org/z/xojTqn3vx

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Thomas Wise (ThomasFWise) requested a review from a team as a code owner May 27, 2021 17:48
@SuperWig

Daniel Marshall (SuperWig) commented May 27, 2021

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If I'm not mistaken, if it's not specified as noexcept in the standard then they need to be commented as // strengthened to signify that.

AdamBucior
Adam Bucior (AdamBucior) reviewed May 27, 2021
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@StephanTLavavej

Stephan T. Lavavej (StephanTLavavej) commented Jul 20, 2021

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I've pushed a merge with main to resolve conflicts in <vector> after the toolset update removed _CONSTEXPR20_CONTAINER (it's now _CONSTEXPR20 or plain constexpr), followed by running clang-format.

@CaseyCarter

Casey Carter (CaseyCarter) commented Aug 25, 2021

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I merged main yet again and resolved a trivial conflict in <optional> where one of the recently removed banner comments appeared in the context around a change.

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Casey Carter (CaseyCarter) suggested changes Jun 29, 2022
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Publishing an ancient partial review.

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@ThomasFWise @strega-nil
Mark several functions as noexcept. This is important for performance…
73e8da6 
… on x86 when calling these functions from code that is marked noexcept.
@strega-nil
CRs:
7baadb1 
- AdamBucior: remove noexcept from compare operators on sequence types
- Casey:
   - _Implicitly_convert_to (_Fake_copy_init)
   - /* strengthened */
CaseyCarter
Casey Carter (CaseyCarter) suggested changes Aug 12, 2022
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CaseyCarter
Casey Carter (CaseyCarter) reviewed Aug 12, 2022
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CaseyCarter
Casey Carter (CaseyCarter) reviewed Aug 12, 2022
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CaseyCarter
Casey Carter (CaseyCarter) suggested changes Aug 12, 2022
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@strega-nil
fix {} () mismatch in move_iterator
b51c536
@strega-nil
Casey CRs
1d6cdf6
@strega-nil
arrrrgh
5e05e92
@strega-nil
fix tests
9afa779 
Additionally, this fixes a few existing XFAILs in libc++'s test suite
CaseyCarter
Casey Carter (CaseyCarter) suggested changes Aug 12, 2022
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CaseyCarter
Casey Carter (CaseyCarter) approved these changes Aug 13, 2022
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@StephanTLavavej

Stephan T. Lavavej (StephanTLavavej) commented Aug 16, 2022

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Merge conflicts need to be resolved now that #1347 has landed. 🛬

@strega-nil-ms

nicole mazzuca (strega-nil-ms) commented Aug 17, 2022

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Merged (and fixed an issue I noticed while merging)

StephanTLavavej
Stephan T. Lavavej (StephanTLavavej) reviewed Aug 17, 2022
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Thanks! I'll validate and push changes for the small issues I found (only one was significant, regarding a missing noexcept annotation on the tagged base class constructor).

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StephanTLavavej
Stephan T. Lavavej (StephanTLavavej) reviewed Aug 17, 2022
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Stephan T. Lavavej (StephanTLavavej) reviewed Aug 17, 2022
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nicole mazzuca (strega-nil-ms) suggested changes Aug 17, 2022
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Marking request changes as I do not wish to merge without finishing the {_Implicitly_convert_to, _Fake_decay_copy, _Fake_copy_init} discussion.

@strega-nil-ms nicole mazzuca (strega-nil-ms) added the decision needed We need to choose something before working on this label Aug 17, 2022
@StephanTLavavej Stephan T. Lavavej (StephanTLavavej) removed the decision needed We need to choose something before working on this label Aug 18, 2022
@StephanTLavavej

Stephan T. Lavavej (StephanTLavavej) commented Aug 18, 2022

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We've decided to go with nicole mazzuca (@strega-nil-ms)'s proposed unification to _Fake_copy_init in a followup PR (to avoid mixing a large mechanical change with a behavioral change).

@StephanTLavavej

Stephan T. Lavavej (StephanTLavavej) commented Aug 18, 2022

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I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

@StephanTLavavej
Stephan T. Lavavej (StephanTLavavej) merged commit ae0c274 into microsoft:main Aug 18, 2022
@StephanTLavavej

Stephan T. Lavavej (StephanTLavavej) commented Aug 18, 2022

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Thomas Wise (@ThomasFWise) Thanks for strengthening these exception specifications, and congratulations on your first microsoft/STL commit!

Also thanks to nicole mazzuca (@strega-nil-ms) for landing this PR!

🎉 😻 🦾

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@frederick-vs-ja A. Jiang (frederick-vs-ja) mentioned this pull request Aug 30, 2026
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@StephanTLavavej Stephan T. Lavavej (StephanTLavavej) StephanTLavavej approved these changes
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@CaseyCarter Casey Carter (CaseyCarter) CaseyCarter approved these changes
@strega-nil-ms nicole mazzuca (strega-nil-ms) strega-nil-ms approved these changes
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