Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Don't deduce the return type of emplace{,_back,_front} #4963

Open
wants to merge 3 commits into
base: main
Choose a base branch
from
Open

Don't deduce the return type of emplace{,_back,_front} #4963

wants to merge 3 commits into from
+76 −9

Conversation

CaseyCarter
Copy link
Member

@CaseyCarter CaseyCarter commented Sep 17, 2024 •
edited
Loading

The instantiation used to deduce the return types of template functions with placeholders in their declared return type happens outside the immediate context of any other template instantiation. Notably, that means the body of such an instantiation isn't an unevaluated context.

Switching to concrete return types will:

  1. Avoid return type deduction, correcting the problem described in DevCom-10745303, and
  2. Correct the ODR problem described in Potential ODR violation linking C++14 with C++17+ TUs that use container emplace functions #4962.

Fixes DevCom-10745303 / VSO-2252142 / AB#2252142

@CaseyCarter CaseyCarter added the bug Something isn't working label Sep 17, 2024
@CaseyCarter CaseyCarter requested a review from a team as a code owner September 17, 2024 23:47
@CaseyCarter
Don't deduce the return type of emplace{,_back,_front}
6209e0b 
The instantiation used to deduce the return types of template functions with placeholders in their declared return type happens outside the immediate context of any other template instantiation. Notably, that means the body of such an instantiation isn't an unevaluated context.

Fixes DevCom-10745303 / VSO-2252142
@CaseyCarter CaseyCarter mentioned this pull request Sep 18, 2024
Open
@CaseyCarter CaseyCarter linked an issue Sep 18, 2024 that may be closed by this pull request
Potential ODR violation linking C++14 with C++17+ TUs that use container emplace functions #4962
Open
@CaseyCarter CaseyCarter mentioned this pull request Sep 18, 2024
Open
@StephanTLavavej StephanTLavavej self-assigned this Sep 19, 2024
@StephanTLavavej
Copy link
Member

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

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Reviewers

@AlexGuteniev AlexGuteniev AlexGuteniev left review comments

@StephanTLavavej StephanTLavavej StephanTLavavej approved these changes

Assignees

@StephanTLavavej StephanTLavavej

Labels
bug Something isn't working
Projects
STL Code Reviews
Status: Ready To Merge
Milestone
No milestone
Development

Successfully merging this pull request may close these issues.

Potential ODR violation linking C++14 with C++17+ TUs that use container emplace functions
3 participants
@CaseyCarter @StephanTLavavej @AlexGuteniev