Answer convertible_to_unexpected for void instead of hard-erroring#306
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Bronek wants to merge 3 commits into
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Answer convertible_to_unexpected for void instead of hard-erroring#306Bronek wants to merge 3 commits into
convertible_to_unexpected for void instead of hard-erroring#306Bronek wants to merge 3 commits into
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This was referenced Jul 13, 2026
🤖 Augment PR SummarySummary: This PR makes the convertibility concepts handle Changes:
Technical Notes: The new guards prevent class-body mandates (e.g. 🤖 Was this summary useful? React with 👍 or 👎 |
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The mandate of `unexpected<void>` fires during instantiation, outside any immediate context - so the concept must not name it for void, which has no unexpected to convert to anyway. Closes #290 Assisted-by: Claude:claude-fable-5
…to_choice` The same class-body mandates that the `convertible_to_unexpected` conjunct keeps out of reach - `optional<void>` and `choice<void>` are ill-formed to instantiate, so each concept says no to void instead of asking. Closes #293 Assisted-by: Claude:claude-fable-5
`remove_cvref_t` folds cv-qualified void back to plain `void` inside each concept's naming, but the guard asked `same_as<T, void>`, which `void const` passes - reaching the same ill-formed instantiations the conjunct exists to avoid. The guard now asks `is_void_v`. `convertible_to_expected`'s arms answer through the same trait: a cv-qualified void is a void, on both sides of the question. Not reachable through deduction - a call expression never has cv-qualified void type ([expr.type]/2) - but the concepts are public surface, and an explicit spelling must get an answer. Assisted-by: Claude:claude-fable-5
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The same void conjunct for all three convertibility concepts whose named type is ill-formed to instantiate for void.
Answer
convertible_to_unexpectedfor void instead of hard-erroringThe mandate of
unexpected<void>fires during instantiation, outside any immediate context - so the concept must not name it for void, which has no unexpected to convert to anyway.Extend the void answer to
convertible_to_optionalandconvertible_to_choiceThe same class-body mandates that the
convertible_to_unexpectedconjunct keeps out of reach -optional<void>andchoice<void>are ill-formed to instantiate, so each concept says no to void instead of asking.Closes #290
Closes #293
Stack: P12 of 13 — the release-0.1 bugfix queue, merging bottom-up into
main. Based on #305 and to be retargeted tomainonce it merges; the diff shows only this PR's commits. Every stack boundary was validated with a gcc build and the full test suite on top ofmain, and the aggregate branch ran the full CI matrix green (#289).