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  1. Qt
  2. QTBUG-116077

Inconsistent hashing between different FP types

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Details

    • Bug
    • Resolution: Unresolved
    • P2: Important
    • None
    • 6.5.2, 6.6.0 Beta2, dev
    • Core: Containers and Algorithms
    • None
    • Ubuntu 20.04, Clang 15, GCC 11, GCC 9
    • c86cf385d (dev), 2d4db1bff (6.5), 3a9bbf235 (6.6), 1845d4332 (dev), c4aa3b0dc (6.7)

    Description

      Besides QTBUG-116076, which is probably still fixable, we also have that

      • qHash(42.f),
      • qHash(42.), and probably also
      • qHash(42.L
        all produce different values.

      Expectation would be, like in the epic, that equal values produce equal hash values.

      This might be fixable in Qt 6, as the double and long double overloads are out-of-line, only the float one is inline and therefore immutable.

      Attachments

        Issue Links

          clones

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-116076 qHash(qfloat16(x), seed) != qHash(float(x), seed) unless seed == 0

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed
          is cloned by

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-116080 Inconsistent hashing between qint{32,64} on 32-bit platforms

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-116064 [REG SiC 6.4 -> 6.5] qHash(qfloat16(x)) is now ambiguous on GCC13

          • P1: Critical - Urgent and Important, will STOP the release if matched with set FixVersion field. This includes regressions from the last version that are not edge cases; Data loss; Build issues; All but the most unlikely crashes/lockups/hanging; Serious usability issues and embarrassing bugs & Bugs critical to a deliverable. This is the highest possible priority for requirements.
          • Closed
          For Gerrit Dashboard: QTBUG-116077
          # Subject Branch Project Status CR V
          496753,3 tst_QHashFunctions: extend the consistency() test with int/FP types dev qt/qtbase Status: MERGED +2 0
          497081,2 tst_QHashFunctions: extend the consistency() test with int/FP types 6.6 qt/qtbase Status: MERGED +2 0
          497082,2 tst_QHashFunctions: extend the consistency() test with int/FP types 6.5 qt/qtbase Status: MERGED +2 0
          536950,6 tst_QHashFunctions: make the consistency check table-driven dev qt/qtbase Status: MERGED +2 0
          539549,2 tst_QHashFunctions: make the consistency check table-driven 6.7 qt/qtbase Status: MERGED +2 0

          Activity

            People

              thiago Thiago Macieira
              mmutz Marc Mutz
              Vladimir Minenko Vladimir Minenko
              Alex Blasche Alex Blasche
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              Dates

                Created:
                Updated: