From e0d475db10f8976060a964517a64cd7b4508cefa Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <ian@gcc.gnu.org>
Date: Tue, 16 Dec 2014 22:53:38 +0000
Subject: [PATCH] compiler: Don't built hash/equality functions for thunk
 structs.

They are never necessary, and they can cause problems when a
thunk is used to pass an unexported type from a different
package to a function defined in that package.  The resulting
struct type may need to call the comparison routine from the
other package, which will fail because the type is not
exported.  This will be bug492 in the master testsuite.

From-SVN: r218798
---
 gcc/go/gofrontend/statements.cc | 17 ++++++++++++++++-
 gcc/go/gofrontend/statements.h  |  7 +++++++
 gcc/go/gofrontend/types.cc      |  4 +++-
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/gcc/go/gofrontend/statements.cc b/gcc/go/gofrontend/statements.cc
index 6eb0d7bcc78..e8c3a3e2702 100644
--- a/gcc/go/gofrontend/statements.cc
+++ b/gcc/go/gofrontend/statements.cc
@@ -1884,6 +1884,8 @@ Statement::make_dec_statement(Expression* expr)
 // Class Thunk_statement.  This is the base class for go and defer
 // statements.
 
+Unordered_set(const Struct_type*) Thunk_statement::thunk_types;
+
 // Constructor.
 
 Thunk_statement::Thunk_statement(Statement_classification classification,
@@ -2265,7 +2267,20 @@ Thunk_statement::build_struct(Function_type* fntype)
 	}
     }
 
-  return Type::make_struct_type(fields, location);
+  Struct_type *st = Type::make_struct_type(fields, location);
+
+  Thunk_statement::thunk_types.insert(st);
+
+  return st;
+}
+
+// Return whether ST is a type created to hold thunk parameters.
+
+bool
+Thunk_statement::is_thunk_struct(const Struct_type* st)
+{
+  return (Thunk_statement::thunk_types.find(st)
+	  != Thunk_statement::thunk_types.end());
 }
 
 // Build the thunk we are going to call.  This is a brand new, albeit
diff --git a/gcc/go/gofrontend/statements.h b/gcc/go/gofrontend/statements.h
index 9bb0fb5aa8d..e12f60fdd30 100644
--- a/gcc/go/gofrontend/statements.h
+++ b/gcc/go/gofrontend/statements.h
@@ -985,6 +985,10 @@ class Thunk_statement : public Statement
   bool
   simplify_statement(Gogo*, Named_object*, Block*);
 
+  // Return whether ST is a type created to hold thunk parameters.
+  static bool
+  is_thunk_struct(const Struct_type *st);
+
  protected:
   int
   do_traverse(Traverse* traverse);
@@ -1023,6 +1027,9 @@ class Thunk_statement : public Statement
   void
   thunk_field_param(int n, char* buf, size_t buflen);
 
+  // A list of all the struct types created for thunk statements.
+  static Unordered_set(const Struct_type*) thunk_types;
+
   // The function call to be executed in a separate thread (go) or
   // later (defer).
   Expression* call_;
diff --git a/gcc/go/gofrontend/types.cc b/gcc/go/gofrontend/types.cc
index 6533cd46ea2..fbcce7f3ed6 100644
--- a/gcc/go/gofrontend/types.cc
+++ b/gcc/go/gofrontend/types.cc
@@ -1593,7 +1593,9 @@ Type::type_functions(Gogo* gogo, Named_type* name, Function_type* hash_fntype,
       hash_fnname = "__go_type_hash_identity";
       equal_fnname = "__go_type_equal_identity";
     }
-  else if (!this->is_comparable())
+  else if (!this->is_comparable() ||
+	   (this->struct_type() != NULL
+	    && Thunk_statement::is_thunk_struct(this->struct_type())))
     {
       hash_fnname = "__go_type_hash_error";
       equal_fnname = "__go_type_equal_error";
-- 
2.30.2