c++: naming typedef and incomplete class [PR126031]

We can't look at the bases and members of a forward-declared nested class,
and such a forward declaration can't contain problematic constructs, so
treat it as OK.

	PR c++/126031
	PR c++/121552

gcc/cp/ChangeLog:

	* decl.cc (maybe_diagnose_non_c_class_typedef_for_linkage): Handle
	incomplete type.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp2a/typedef2.C: New test.

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 79247302608d373ebd1cf7ef4d414d0cd0470b51..a22331073173b7f41233e940e14b21188fce6583 100644 (file)
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -13775,6 +13775,8 @@ diagnose_non_c_class_typedef_for_linkage (tree type, tree orig)
 static bool
 maybe_diagnose_non_c_class_typedef_for_linkage (tree type, tree orig, tree t)
 {
+  if (!COMPLETE_TYPE_P (t))
+    return false;
   if (!BINFO_BASE_BINFOS (TYPE_BINFO (t))->is_empty ())
     {
       auto_diagnostic_group d;

diff --git a/gcc/testsuite/g++.dg/cpp2a/typedef2.C b/gcc/testsuite/g++.dg/cpp2a/typedef2.C
new file mode 100644 (file)
index 0000000..e4a8195
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/typedef2.C
@@ -0,0 +1,5 @@
+// PR c++/126031
+
+typedef struct {
+  struct S;
+} s;