Constant is broken on MSVC
#364
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⬇️ affects: code (implementation)
Affects implementation details of the code
📁 kind: bug
Something isn't working correctly, or there's a mistake
💪 effort: tiny
A trivial change
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chiphogg
added
📁 kind: bug
chiphogg
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Dec 18, 2024
Some comments on the vcpkg PR to upgrade Au to 0.4.0 made me suspicious
that we lacked coverage here. I added a test case, and sure enough, it
[broke].
What's happening here is that MSVC is being _extremely persnickety_
about what we pass to a `static_assert`. We are passing a function
parameter, which _in the general case_ might be a **runtime** value;
hence, inappropriate for `static_assert`.
What MSVC doesn't know is that `OtherUnit` is a [monovalue type], so it
can only ever have one possible value, and therefore that value _is_
knowable at compile time. That said, since it _is_ a monovalue type,
that means that it's safe to replace the instance `u` with an ad hoc
construction of the type name, `OtherUnit{}`. This appeases MSVC.
Helps #364: we'll go over every other `static_assert` before closing.
[broke]:
https://github.com/aurora-opensource/au/actions/runs/12395185495/job/34600303870
[monovalue type]:
https://aurora-opensource.github.io/au/main/reference/detail/monovalue_types
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Discovered in this comment (microsoft/vcpkg#42679 (comment)). We can easily reproduce by adding a test case involving
Constantto our MSVC test file.The text was updated successfully, but these errors were encountered: