stillwater-sc / universal / 30545755105

85%

master: 84%

Build Type

push

github

Committed by web-flow

Commit Message

fix: eliminate shift-mask narrowing via shared bit_high_mask helper (#1261) (#1267)

The left-shift operators build the upper-bits mask as an unsuffixed 64-bit
literal and implicitly narrow it to the limb type bt:

    bt mask = 0xFFFFFFFFFFFFFFFF << (bitsInBlock - bitsToShift);

so GCC/Clang -Wconversion and MSVC C4244 fire at every instantiation. The
literal's type is also platform-dependent (unsigned long on LP64 vs unsigned
long long on Windows), which is why the two report different messages.

Sibling of #1260 (same warning-clean Epic #1265), so extend the same shared
helper header. Add bit_high_mask<bt>(count, bitsInBlock) to
internal/bit_manipulation.hpp -- the highest `count` bits of a limb, all-ones
shifted left and narrowed explicitly (warning-free, platform-independent) -- and
route the sites through it.

The issue listed 2 files; the idiom was actually in 5 (blockbinary,
blocksignificand, blockfraction, areal, cfloat). The issue's proposed inline
`ALL_ONES` fix would not compile for areal/cfloat (no ALL_ONES limb constant --
cfloat only has ALL_ONES_FR/ALL_ONES_ES), so the shared helper is the uniform
fix and matches the Epic's intent. All 5 files already include
bit_manipulation.hpp from #1260, so no new includes.

Verified: bit_high_mask is -Wconversion/-Werror clean on gcc + clang and matches
the original literal for every shift of uint8/16/32/64; blockbinary<64,bt> <<= k
matches a uint64 shift for all bt and all k (the exercised code path). Regression
added to internal/blockbinary/api/bit_clear_mask.cpp. bb_api, cfloat_api/
assignment, areal_api, posit_api PASS on both compilers; all consumers compile
clean.

Resolves #1261

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Coverage Stats

18 of 23 new or added lines in 6 files covered. (78.26%)

8 existing lines in 1 file now uncovered.

41634 of 48868 relevant lines covered (85.2%)

7274196.97 hits per line