commit 52ebad939927e6cbfb48dd277cef8db451e36533
author Than McIntosh <thanm@google.com> Fri Sep 08 10:56:13 2017 -0400
committer Ian Lance Taylor <iant@golang.org> Sat Sep 09 06:00:19 2017 +0000
tree 63bf54f26cddf0a83b863ceda08c172e71fd159d
parent 9d0d5c03a8086f5dd3a23e910abd6e470196973c

compiler: guard against implicit double pointer indirection

The code that lowers field references can sometimes introduce a double
pointer indirection in cases where it is not/safe appropriate. For
example, in

        var p **struct { f int }
        p.f = 0

the assignment LHS was being incorrectly lowered to (*(*p)).f.
Detect this situation and issue an error.

Fixes golang/go#21770

Change-Id: I350e0696e0aa7032114797fe21dc54faa0a44933
Reviewed-on: https://go-review.googlesource.com/62330
Reviewed-by: Ian Lance Taylor <iant@golang.org>

go/types.cc

diff --git a/go/types.cc b/go/types.cc
index 4d92373..cde1408 100644
--- a/go/types.cc
+++ b/go/types.cc
@@ -11829,6 +11829,12 @@
 	  go_assert(st != NULL);
 	  if (type->struct_type() == NULL)
 	    {
+              if (dereferenced)
+                {
+                  go_error_at(location, "pointer type has no field %qs",
+                              Gogo::message_name(name).c_str());
+                  return Expression::make_error(location);
+                }
 	      go_assert(type->points_to() != NULL);
 	      expr = Expression::make_unary(OPERATOR_MULT, expr,
 					    location);