re PR c/2735 (can't cast a union type defined by a typedef to itself)

	* c-typeck.c (build_c_cast): Use TYPE_MAIN_VARIANT when checking
	for casting an aggregate to its own type.  Fixes PR c/2735.

testsuite:
	* gcc.c-torture/compile/20010605-2.c: New test.

From-SVN: r42900

gcc/ChangeLog

 2001-06-05  Joseph S. Myers  <jsm28@cam.ac.uk>
 
+	* c-typeck.c (build_c_cast): Use TYPE_MAIN_VARIANT when checking
+	for casting an aggregate to its own type.  Fixes PR c/2735.
+
+2001-06-05  Joseph S. Myers  <jsm28@cam.ac.uk>
+
 	* doc/texinfo.tex: Update to version 2001-05-24.08.
 
 2001-06-05  Nathan Sidwell  <nathan@codesourcery.com>

gcc/c-typeck.c

@@ -3719,7 +3719,7 @@ build_c_cast (type, expr)
       return error_mark_node;
     }
 
-  if (type == TREE_TYPE (value))
+  if (type == TYPE_MAIN_VARIANT (TREE_TYPE (value)))
     {
       if (pedantic)
 	{

gcc/testsuite/ChangeLog

+2001-06-05  Joseph S. Myers  <jsm28@cam.ac.uk>
+
+	* gcc.c-torture/compile/20010605-2.c: New test.
+
 2001-06-04  John David Anglin  <dave@hiauly1.hia.nrc.ca>
 
 	* gcc.c-torture/execute/20010604-1.c: New test.

gcc/testsuite/gcc.c-torture/compile/20010605-2.c

+/* Origin: Joseph Myers <jsm28@cam.ac.uk>.  */
+/* As an extension, GCC allows a struct or union to be cast to its own
+   type, but failed to allow this when a typedef was involved.
+   Reported as PR c/2735 by <cowan@ccil.org>.  */
+union u { int i; };
+typedef union u uu;
+union u a;
+uu b;
+
+void
+foo (void)
+{
+  a = (union u) b;
+  a = (uu) b;
+  b = (union u) a;
+  b = (uu) a;
+}