The TestIssue22073 test in reflect package is currently not passing without some modifications. This is because the GopherJS doesn't produce correct method set order when method names begin with non-ASCII characters.

Before Go 1.10, methods were sorted by name. That happened to guarantee that exported ASCII methods appear before non-exported ASCII methods, but it broke down when Unicode method names were considered. Go 1.10 changed that in golang/go@6f1724f. GopherJS needs to be updated to match behavior.

Currently, its method set sorting code, implemented in JavaScript in compiler/prelude/types.go, sorts by name:

typ.methodSetCache = [];
Object.keys(base).sort().forEach(function(name) {
  typ.methodSetCache.push(base[name]);
});
return typ.methodSetCache;

For the given type:

type NonExportedFirst int

func (i NonExportedFirst) ΦExported()       {}
func (i NonExportedFirst) nonexported() int { panic("wrong") }

That code puts nonexported before ΦExported (encoded as "\xCE\xA6Exported"). That's not correct.

The following hacky fix, temporarily tested out via c4db7b2 (but eventually reverted in 88dc1af), made the test pass:

typ.methodSetCache = [];
var x = Object.keys(base).sort();
if (x.length === 2 && x[0] === "nonexported" && x[1] === "\xCE\xA6Exported") {
  /* HACK: Hacky fix for TestIssue22073. Need to find a good general fix. */
  x[0] = "\xCE\xA6Exported";
  x[1] = "nonexported";
}
x.forEach(function(name) {
  typ.methodSetCache.push(base[name]);
});
return typ.methodSetCache;

It needs to be generalized and applied to resolve the issue.