Fix static-analysis issues: apply hidden friend pattern to binary ope… #781

All 3 594 tests pass in 1s

8 files ±0 8 suites ±0 1s ⏱️ ±0s
3 594 tests ±0 3 594 ✅ ±0 0 💤 ±0 0 ❌ ±0
9 486 runs ±0 9 486 ✅ ±0 0 💤 ±0 0 ❌ ±0

Results for commit 592b68c. ± Comparison against earlier commit 6d02e75.