c-typeck.c (lookup_field): If -fplan9-extensions, permit referring to a field using a typedef name.

gcc/:
	* c-typeck.c (lookup_field): If -fplan9-extensions, permit
	referring to a field using a typedef name.
	(find_anonymous_field_with_type): New static function.
	(convert_to_anonymous_field): New static function.
	(convert_for_assignment): If -fplan9-extensions, permit converting
	pointer to struct to pointer to anonymous field.
	* c-decl.c (grokfield): If -fplan9-extensions, permit anonymous
	fields.
	(is_duplicate_field): New static function.
	(detect_field_duplicates_hash): If -fplan9-extensions, check for
	typedef names duplicating field names.
	(detect_field_duplicates): Likewise.
	* doc/invoke.texi (Option Summary): Mention -fplan9-extensions.
	(C Dialect Options): Document -fplan9-extensions.
	* doc/extend.texi (Unnamed Fields): Document -fplan9-extensions.
gcc/c-family/:
	* c.opt (-fplan9-extensions): New option.
gcc/testsuite/:
	* gcc.dg/anon-struct-11.c: New test.
	* gcc.dg/anon-struct-12.c: New test.
	* gcc.dg/anon-struct-13.c: New test.
	* gcc.dg/anon-struct-14.c: New test.

From-SVN: r164926

1 files changed, 76 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.dg/anon-struct-13.c b/gcc/testsuite/gcc.dg/anon-struct-13.c
new file mode 100644
index 0000000..6a50814
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/anon-struct-13.c
@@ -0,0 +1,76 @@
+/* { dg-do compile } */
+/* { dg-options "-fplan9-extensions" } */
+
+/* Test for ambiguity when using the Plan 9 extensions.  */
+
+struct A {
+  char a;		/* { dg-error "duplicate member" } */
+};
+
+struct B
+{
+  struct A;
+  struct A;
+};
+
+char
+f1 (struct B *p)
+{
+  return p->a;		/* { dg-error "no member" } */
+}
+
+void
+f2 (struct A *p)	/* { dg-message "expected" } */
+{
+}
+
+void
+f3 (struct B *p)
+{
+  f2 (p);		/* { dg-warning "incompatible pointer type" } */
+}
+
+struct C
+{
+  char c;		/* { dg-error "duplicate member" } */
+};
+
+struct D
+{
+  struct C;
+};
+
+struct E
+{
+  struct C;
+  struct D;
+};
+
+char
+f4 (struct E *p)
+{
+  return p->c;		/* { dg-error "no member" } */
+}
+
+void
+f6 (struct C *p)	/* { dg-message "expected" } */
+{
+}
+
+void
+f7 (struct E *p)
+{
+  f6 (p);		/* { dg-warning "incompatible pointer type" } */
+}
+
+struct A
+f8 (struct B *p)
+{
+  return p->A;		/* { dg-error "no member" } */
+}
+
+struct C
+f9 (struct E *p)
+{
+  return p->C;		/* { dg-error "no member" } */
+}