| Bug #81639 | Replace the macro IS_SINGLE_FLAG() with a portable constexpr function | ||
|---|---|---|---|
| Submitted: | 30 May 2016 8:25 | Modified: | 30 May 2016 13:39 |
| Reporter: | Marko Mäkelä | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server: Compiling | Severity: | S3 (Non-critical) |
| Version: | 8.0.0 | OS: | Any |
| Assigned to: | CPU Architecture: | Any | |
[30 May 2016 13:39]
Paul DuBois
Posted by developer: Fixed in 5.8.0. Code cleanup. No changelog entry needed.
[18 Jun 2016 21:38]
Omer Barnir
Posted by developer: Reported version value updated to reflect release name change from 5.8 to 8.0
Description: MySQL needs a predicate that can check if there is a single bit set in an integer. sql/parse_tree_nodes.h already defines the macro IS_SINGLE_FLAG(X), but it is not portable, because it depends on the GCC __builtin_popcount(). That is acceptable for static_assert() but not for more general use. How to repeat: See above. Suggested fix: In my_bit.h, introduce template<typename IntType> constexpr bool is_single_bit(IntType bits) { return bits != 0 && (bits & (bits - 1)) == 0; }