Remove default(none) clause in some OpenMP for-loops #5903
Merged
Conversation
This file contains 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
clang 17 complains that in these loops, some variables do not have an explicitly defined data sharing attribute, e.g. `Eigen::Dynamic` (which is a `const int`). Explicitly defining it as shared would be weird since the use of `Eigen::Dynamic` is not obvious in those loops, and would also likely lead to problems with other compilers because const variables are implicitly shared (at least in OpenMP versions < 4.0), and defining them explicitly as shared leads to compiler errors (see also http://jakascorner.com/blog/2016/07/omp-default-none-and-const.html). Removing default(none) solves the problem. Generally, the use of default(none) is recommended while writing the code because it forces the programmer to think about whether each variable should be shared or private, but since the code is already finished, removing default(none) should have no downsides.
larshg
approved these changes
Dec 18, 2023
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
clang 17 complains that in these loops, some variables do not have an explicitly defined data sharing attribute, e.g.
Eigen::Dynamic(which is aconst int).Explicitly defining it as shared would be weird since the use of
Eigen::Dynamicis not obvious in those loops, and would also likely lead to problems with other compilers because const variables are implicitly shared (at least in OpenMP versions < 4.0), and defining them explicitly as shared leads to compiler errors (see also http://jakascorner.com/blog/2016/07/omp-default-none-and-const.html).Removing default(none) solves the problem. Generally, the use of default(none) is recommended while writing the code because it forces the programmer to think about whether each variable should be shared or private, but since the code is already finished, removing default(none) should have no downsides.
Also: install libomp-dev to make OpenMP available for Clang on CI