spec: cyclic imports are illegal
Fixes #4976.
R=r
CC=golang-dev
https://golang.org/cl/7421050
diff --git a/doc/go_spec.html b/doc/go_spec.html
index 0cb9f54..83e0f58 100644
--- a/doc/go_spec.html
+++ b/doc/go_spec.html
@@ -1,6 +1,6 @@
<!--{
"Title": "The Go Programming Language Specification",
- "Subtitle": "Version of March 1, 2013",
+ "Subtitle": "Version of March 4, 2013",
"Path": "/ref/spec"
}-->
@@ -5367,7 +5367,8 @@
<p>
An import declaration declares a dependency relation between
the importing and imported package.
-It is illegal for a package to import itself or to import a package without
+It is illegal for a package to import itself, directly or indirectly,
+or to directly import a package without
referring to any of its exported identifiers. To import a package solely for
its side-effects (initialization), use the <a href="#Blank_identifier">blank</a>
identifier as explicit package name:
