[CPyCppyy] Work around non-instantiable std::span iterators in GCC 15#20891
Merged
Conversation
guitargeek
added
bug
in:Python Interface
experiment
1 task
Contributor
Author
|
@sponce To which releases would you need this packported? |
|
Ideally LCG108 version, so 6.36 |
guitargeek
force-pushed
the
issue-18837
branch
from
8ff2c9e to
253be89
Compare
Test Results 22 files 22 suites 3d 18h 48m 15s ⏱️ Results for commit 7b307b1. ♻️ This comment has been updated with latest results. |
guitargeek
force-pushed
the
issue-18837
branch
3 times, most recently
from
1780879 to
b5dac61
Compare
Contributor
Author
|
Requires #20895 to work also on Windows. |
The libstdc++ (GCC >= 15) implements `std::span::iterator` using a private nested tag type, which makes the iterator non-instantiable by CallFunc-generated wrappers (the return type cannot be named without violating access rules). To preserve correct Python iteration semantics, this commit suggests to replace `begin()`/`end()` for `std::span` to return a custom pointer-based iterator instead. This avoids relying on `std::span::iterator` while still providing a real C++ iterator object that CPyCppyy can also wrap and expose via `__iter__`/`__next__`. A unit test is implemented based on the reproducers provided in root-project#18837. Closes root-project#18837.
guitargeek
force-pushed
the
issue-18837
branch
from
b5dac61 to
7b307b1
Compare
Member
This is now merged into master, right? |
Contributor
Author
|
Yes, correct! So for me this PR is good to go. But it should be only a temporary solution that is safe to backport. The sustainable fix for #18837 will be to fix TClingCallFunc. |
dpiparo
approved these changes
Jan 17, 2026
This was referenced Jan 17, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The libstdc++ (GCC >= 15) implements
std::span::iteratorusing a private nested tag type, which makes the iterator non-instantiable by CallFunc-generated wrappers (the return type cannot be named without violating access rules).To preserve correct Python iteration semantics, this commit suggests to replace
begin()/end()forstd::spanto return a custom pointer-based iterator instead. This avoids relying onstd::span::iteratorwhile still providing a real C++ iterator object that CPyCppyy can also wrap and expose via__iter__/__next__.A unit test is implemented based on the reproducers provided in #18837.
Closes #18837.