Keep struct in a when ^T struct static optimization - #3516
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The printer wrote only the type parameter of a WhenTyparIsStruct constraint, so `when ^T struct = 0` became `when ^T = 0`, which does not parse. The case that pinned the bug as ignored now runs as a regular negative case. Fixes fsprojects#3514
Conditions of one `when` were printed with only a space between them, so `when ^T : int and ^U struct` lost its `and`. The parser also keeps those conditions in reverse, and nests several `when` clauses with the first one outermost, so formatting reversed both. Reversed conditions put the Oak children out of source order, and reversed clauses made the result swap back on every format. The transformer now rebuilds the clauses and their conditions in source order, and the printer joins conditions with `and`.
This was referenced Oct 5, 2026
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The printer wrote only the type parameter of a WhenTyparIsStruct constraint, so
when ^T struct = 0becamewhen ^T = 0, which does not parse. The case that pinned the bug as ignored now runs as a regular negative case.Fixes #3514