From: Jason Merrill <jason@redhat.com>
Date: Mon, 12 Sep 2022 18:14:24 +0000 (-0400)
Subject: c++: cast to array of unknown bound [PR93259]
X-Git-Tag: release-12.2.mpacbti-rel1~435
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8f37a44483870e0db8cd6437ae9716cbe28b7f59;p=thirdparty%2Fgcc.git

c++: cast to array of unknown bound [PR93259]

We already know to treat a variable of array-of-unknown-bound type as
dependent, we should do the same for arr{}.

	PR c++/93259

gcc/cp/ChangeLog:

	* pt.cc (type_dependent_expression_p): Treat a compound
	literal of array-of-unknown-bound type like a variable.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/initlist-array17.C: New test.
---

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index bef31416fb77..2f3cbf4895df 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -27952,11 +27952,11 @@ type_dependent_expression_p (tree expression)
      If the array has no length and has an initializer, it must be that
      we couldn't determine its length in cp_complete_array_type because
      it is dependent.  */
-  if (VAR_P (expression)
+  if (((VAR_P (expression) && DECL_INITIAL (expression))
+       || COMPOUND_LITERAL_P (expression))
       && TREE_TYPE (expression) != NULL_TREE
       && TREE_CODE (TREE_TYPE (expression)) == ARRAY_TYPE
-      && !TYPE_DOMAIN (TREE_TYPE (expression))
-      && DECL_INITIAL (expression))
+      && !TYPE_DOMAIN (TREE_TYPE (expression)))
    return true;
 
   /* Pull a FUNCTION_DECL out of a BASELINK if we can.  */
diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist-array17.C b/gcc/testsuite/g++.dg/cpp0x/initlist-array17.C
new file mode 100644
index 000000000000..c4284a7b3913
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/initlist-array17.C
@@ -0,0 +1,37 @@
+// PR c++/93259
+// { dg-do compile { target c++11 } }
+
+template <class T, class U> struct is_same;
+template <class T> struct is_same<T,T> { };
+
+using Array = int[];
+
+template <typename ...Ts>
+void bar1(Ts ...)
+{
+  auto && array = Array{ 1, 2, 3 };
+
+  is_same<int (&&)[3], decltype(array)>{}; // this fails, deduces array as int (&&) []
+}
+
+template <typename T>
+void bar2()
+{
+  auto && array = Array{ 1, 2, 3 };
+
+  is_same<int (&&)[3], decltype(array)>{};  // this fails, deduces array as int (&&) []
+}
+
+void bar3()
+{
+  auto && array = Array{ 1, 2, 3 };
+
+  is_same<int (&&)[3], decltype(array)>{}; // OK
+}
+
+int main()
+{
+  bar1<int>(1, 2, 3);
+  bar2<int>();
+  bar3();
+}