A minor incompatibility in Go 1.25

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Bob Glickstein

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Aug 14, 2025, 1:12:46 AM Aug 14

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I just discovered the hard way (where hard == a few hours of debugging) that, beginning in Go 1.25, "any" type-checks (in the "go/types".Config.Check sense) as a *types.Alias . Previously it type-checked as a *types.Interface . This caused a test breakage when updating Modver , which I have fixed here .

Not sure whether this rises to the level of a bug report. It is at least a public-service announcement.

Cheers,

- Bob

David Harkness

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Aug 20, 2025, 2:55:35 PM Aug 20

to golang-nuts

According to the types.Alias documentation, this was changed because Go 1.24 added the ability for a type alias to have generic arguments, e.g. type Set[K comparable] = map[K]bool . You can use Unalias to get the underlying type.

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