go.tools/go/types: inferred type for value,ok-mode expressions includes assignability conversions #7060
Description
Both of these functions contain expressions (m[1] and <-ch) that appear in a
"value,ok" context.
func f() (i interface{}, ok bool) {
m := map[int]string{1: "hi"}
i, ok = m[1]
return
}
func g() (i interface{}, ok bool) {
ch := make(chan string, 1)
ch <- "hi"
i, ok = <- ch
return
}
I would expect the inferred types for both to be (string, bool), but in fact both are
(interface{}, bool). i.e. the type checker has incorporated the type conversion to the
assignment's LHS into the type that is inferred. This is not ideal because a compiler
(for example) would assume that no conversion is necessary since the LHS and RHS types
are identical.