What version of Go are you using (go version)?

$ go version
go version devel go1.19-d3d7998756 Tue Jul 12 04:04:17 2022 +0000 linux/amd64

Does this issue reproduce with the latest release?

Yes

What did you do?

Consider

func fn(int) {}

func bar() {
	const oracle = assist.A * assist.B
	fn(oracle)
}

with

const A = 0.05
const B = 10000

The two constants are untyped floats, and their product is 500.0. The Go compiler accepts the function call. When using go/types, however, this only type checks if we're not loading assist from export data. If we are, then it fails with

cannot use oracle (untyped float constant 500) as int value in argument to fn (truncated)

The following txtar archive contains a module with a package bug that compiles fine using go build, but fails to type check when loading with go/packages. Notably, this only fails when a) the constants are declared in an imported package b) the imported package is loaded from export data instead of from source.

Output:

$ go build ./...  
$ go run run_me.go
example.com/bug [/tmp/foo/bug/foo.go:11:5: cannot use oracle (untyped float constant 500) as int value in argument to fn (truncated)]

Input:

https://go.dev/play/p/LZfQZ7oKOcW.go

Possibly related to #45837

/cc @griesemer