c++: decltype of capture proxy of ref [PR115504]

The finish_decltype_type capture proxy handling added in r14-5330 was
incorrectly stripping references in the type of the captured variable.

	PR c++/115504

gcc/cp/ChangeLog:

	* semantics.cc (finish_decltype_type): Don't strip the reference
	type (if any) of a capture proxy's captured variable.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp1y/decltype-auto8.C: New test.

Reviewed-by: Jason Merrill <jason@redhat.com>

diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 8e3e4e23b72df613302090a269beb17636523ea4..44de4c9a5293bd4d47c3c3498ae7d79e5cf807af 100644 (file)
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12071,7 +12071,6 @@ finish_decltype_type (tree expr, bool id_expression_or_member_access_p,
                {
                  expr = DECL_CAPTURED_VARIABLE (expr);
                  type = TREE_TYPE (expr);
-                 type = non_reference (type);
                }
              else
                {

diff --git a/gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C b/gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C
new file mode 100644 (file)
index 0000000..55135ce
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/decltype-auto8.C
@@ -0,0 +1,22 @@
+// PR c++/115504
+// { dg-do compile { target c++14 } }
+
+void f(int& x, const int& y) {
+  [&x]() {
+    decltype(auto) a = x;
+    using type = decltype(x);
+    using type = decltype(a);
+    using type = int&; // not 'int'
+  };
+
+  [x]() {
+    decltype(auto) a = x; // { dg-error "discards qualifiers" }
+  };
+
+  [x]() mutable {
+    decltype(auto) a = x;
+    using type = decltype(x);
+    using type = decltype(a);
+    using type = int&;
+  };
+}