Hi!
Two years ago Paolo has added the
else if (processing_template_decl && !COMPLETE_TYPE_P (type))
pedwarn (...);
lines into cp_finish_decomp. For type dependent decl we punt much earlier,
but even for types which aren't type dependent COMPLETE_TYPE_P might be
false as this testcase shows, so this patch tries to complete_type first
(the reason for writing it that way is that it is then followed by another
else if and if complete_type returns error_mark_node, we shouldn't report
anything, as a bug should have been reported already.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2020-05-27 Jakub Jelinek <ja...@redhat.com>
PR c++/95328
* decl.c (cp_finish_decomp): Call complete_type before checking
COMPLETE_TYPE_P.
* g++.dg/cpp1z/decomp53.C: New test.
--- gcc/cp/decl.c.jj 2020-05-22 11:07:21.884215758 +0200
+++ gcc/cp/decl.c 2020-05-26 15:21:25.039880747 +0200
@@ -8392,6 +8392,8 @@ cp_finish_decomp (tree decl, tree first,
error_at (loc, "cannot decompose lambda closure type %qT", type);
goto error_out;
}
+ else if (processing_template_decl && complete_type (type) == error_mark_node)
+ goto error_out;
else if (processing_template_decl && !COMPLETE_TYPE_P (type))
pedwarn (loc, 0, "structured binding refers to incomplete class type %qT",
type);
--- gcc/testsuite/g++.dg/cpp1z/decomp53.C.jj 2020-05-26 15:25:01.397644953
+0200
+++ gcc/testsuite/g++.dg/cpp1z/decomp53.C 2020-05-26 15:24:37.764998398
+0200
@@ -0,0 +1,22 @@
+// PR c++/95328
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+template <typename T>
+struct S
+{
+ int a, b;
+};
+
+template <typename T>
+void
+foo ()
+{
+ auto [a, b] = S<int>(); // { dg-warning "structured bindings only
available with" "" { target c++14_down } }
+}
+
+int
+main ()
+{
+ foo<int> ();
+}
Jakub
