To expand on Kevin's answer: To call a function, the argument must be assignable <https://golang.org/ref/spec#Assignability> to the parameter type of the function. In this case, none of the types involved is a defined type, channel, interface, pointer…, so the only case left for them to be assignable would be if the types are identical <https://golang.org/ref/spec#Type_identity>, and:
Two struct types are identical if they have the same sequence of fields, > and if corresponding fields have the same names, and identical types, and > identical tags. *Non-exported field names from different packages are > always different*. (emphasis mine) Therefore, in the case of `b.F(s)` does not work, as the `byte` fields have different names - they might be written out the same, but as they are from different packages, they are considered different names. `f(s)` *does* work, as in that case the field names are from the same package. reflect <https://pkg.go.dev/reflect#StructField> also exposes this semantic. For unexported fields (and only for those) it sets the `PkgPath` as well. So you can think of unexported field names as being implicitly qualified by their package path. On Tue, Nov 16, 2021 at 11:51 PM Óscar Carrasco <oxc...@gmail.com> wrote: > Hello, my issue is similar to: > > https://stackoverflow.com/questions/38784963/exporting-functions-with-anonymous-struct-as-a-parameter-cannot-use-value-type > > In this particular case, it is fixed by exporting the fields capitalizing > the field name. But, what if the struct fields are also anonymous? > > main.go: > ---------------------------------------------------- > package main > > import "a/b" > > func f(s struct{ byte }) {} > > func main() { > s := struct{ byte }{} > f(s) // This works > b.F(s) // This gives an argument type error > } > ---------------------------------------------------- > > b/b.go: > ---------------------------------------------------- > package b > > func F(c struct{ byte }) { > } > ---------------------------------------------------- > > By building this code, we get the following compiler error: > `cannot use s (type struct { byte }) as type struct { byte } in argument > to b.F` > > In my opinion, it should be allowed to export the unnamed (anonymous) > types so the struct can be used anywhere else. Opinions on this? > > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/dcd6d246-4091-49da-8631-450829e6de68n%40googlegroups.com > <https://groups.google.com/d/msgid/golang-nuts/dcd6d246-4091-49da-8631-450829e6de68n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAEkBMfHPuMG3y0cyE9pOCbDC7xTKLrKC4RiJxOZrarzK-u5%2BMw%40mail.gmail.com.
