stillwater-sc / universal / 25407703044

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Committed by web-flow

Commit Message

feat(valid): partial constexpr support (API surface) (#821)

* feat(valid): partial constexpr support (API surface)

Promote the valid type's user-facing surface to constexpr / CONSTEXPRESSION.
The valid type is interval arithmetic with posit endpoints; per the issue,
"constexpr coverage is mostly transitive from #718" (posit constexpr).
posit1 is fully constexpr, so the valid promotion is largely annotation.

Promoted (this PR)

  * default constructor (constexpr) and copy / move (constexpr default)
  * native-type ctors / operator= (CONSTEXPRESSION via _assign template)
  * compound arithmetic stubs (+= -= *= /=) -- currently no-ops, marked
    constexpr so the surface lights up at constant evaluation today
  * selectors (isopen, isclosed, isopenlower, isopenupper, getlb, getub)
    constexpr
  * modifiers (clear, setinclusive, setlb, setub, setbits) constexpr
  * friend comparison operators (==, !=, <, <=, >, >=) constexpr -- the
    stub returns are unchanged (false), but the surface is now usable in
    static_assert
  * binary arithmetic free functions (+, -, *, /) constexpr -- compose
    from the compound stubs
  * literal-rhs comparison operators with double CONSTEXPRESSION

Constexpr-callable surface today (gcc + clang, C++20)

  * Default ctor and selectors at constant evaluation
  * clear() at constant evaluation (uses bitblock::reset which is
    constexpr-overridden)
  * Compound arithmetic stubs (+= etc.) and binary free functions
    (+ etc.) at constant evaluation -- they're no-ops so the
    constexpr-ness is a contract lock-in
  * Comparison operators at constant evaluation (stub-false)

Limited at constant evaluation today (transitive, not in scope)

  * setnar / setbits / setinclusive paths through std::bitset::set,
    which is not constexpr until C++23.  Marked constexpr so they will
    light up automatically when the toolchain catches up.
  * Native-type ctors / operator=(int|double|...) -- _assign() builds an
    internal::va... (continued)

Coverage Stats

18 of 18 new or added lines in 1 file covered. (100.0%)

8 existing lines in 1 file now uncovered.

45870 of 54644 relevant lines covered (83.94%)

6477427.06 hits per line