tree c8e3fd99782ada63f844770dccc50025b60a80ef
parent 9146ac14ee1e7516e2bb4212c0fcf054c6dde640
author Robert Griesemer <gri@golang.org> 1354814240 -0800
committer Robert Griesemer <gri@golang.org> 1354814240 -0800
golang-hg 1f28d9979753517d9cd2cfb58ec7e3ea032ff267

spec: type assertions and type switches must be valid

The spec didn't preclude invalid type assertions and
type switches, i.e., cases where a concrete type doesn't
implement the interface type in the assertion in the first
place. Both, the gc and gccgo compiler exclude these cases.
This is documenting the status quo.

Also:
- minor clean up of respective examples
- added sentence about default case in select statements

Fixes #4472.

R=rsc, iant, r, ken
CC=golang-dev
https://golang.org/cl/6869050