cmd/guru: fix incorrect case order in describe.go

Since *ast.CommClause implements ast.Stmt, type switch for
it would never execute in the original code, it will always
execute ast.Stmt branch.

Moving concrete types before interfaces help in this case.

Change-Id: Id84f2f7f3fac859029155d8e6debf4a8ef170b26
Reviewed-on: https://go-review.googlesource.com/c/153397
Run-TryBot: Brad Fitzpatrick <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>

cmd/guru/describe.go

@@ -162,6 +162,9 @@ func findInterestingNode(pkginfo *loader.PackageInfo, path []ast.Node) ([]ast.No
 			path = append([]ast.Node{n.Name}, path...)
 			continue
 
+		case *ast.Comment, *ast.CommentGroup, *ast.File, *ast.KeyValueExpr, *ast.CommClause:
+			return path, actionUnknown // uninteresting
+
 		case ast.Stmt:
 			return path, actionStmt
 
@@ -173,9 +176,6 @@ func findInterestingNode(pkginfo *loader.PackageInfo, path []ast.Node) ([]ast.No
 			*ast.ChanType:
 			return path, actionType
 
-		case *ast.Comment, *ast.CommentGroup, *ast.File, *ast.KeyValueExpr, *ast.CommClause:
-			return path, actionUnknown // uninteresting
-
 		case *ast.Ellipsis:
 			// Continue to enclosing node.
 			// e.g. [...]T in ArrayType