iter: document that calling yield after terminated range loop causes runtime panic

The existing documentation isn't clear about the behaviour of when
the iterator function ignores the value returned from the yield function.

The changes here update the documentation, to explicitly explain
that.

Change-Id: I24a8198c3da63429358554169697fa466345b8fd
GitHub-Last-Rev: 86c8a2dd89dca4e05631f5c4f7087b59b0e0664b
GitHub-Pull-Request: golang/go#74561
Reviewed-on: https://go-review.googlesource.com/c/go/+/687215
Auto-Submit: Sean Liao <sean@liao.dev>
Reviewed-by: Sean Liao <sean@liao.dev>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Mark Freeman <markfreeman@google.com>

diff --git a/src/iter/iter.go b/src/iter/iter.go
index 3eaeb9e1fd6f1ff5b1d43d8dfd9d6a6573f33566..3d0caebf1ed5c56985e11cf4b7d1416ac0c6924a 100644 (file)
--- a/src/iter/iter.go
+++ b/src/iter/iter.go
@@ -28,6 +28,8 @@ or index-value pairs.
 Yield returns true if the iterator should continue with the next
 element in the sequence, false if it should stop.
 
+Yield panics if called after it returns false.
+
 For instance, [maps.Keys] returns an iterator that produces the sequence
 of keys of the map m, implemented as follows: