PR libstdc++/90220 Fix std::any_cast for function pointers

	PR libstdc++/90220 (partial)
	* include/std/any (any_cast<T>(any*), any_cast<T>(const any*)): Do
	not attempt ill-formed static_cast to pointers to non-object types.
	* testsuite/20_util/any/misc/any_cast.cc: Test std::any_cast with
	function types.

From-SVN: r270538

libstdc++-v3/ChangeLog

 2019-04-24  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/90220 (partial)
+	* include/std/any (any_cast<T>(any*), any_cast<T>(const any*)): Do
+	not attempt ill-formed static_cast to pointers to non-object types.
+	* testsuite/20_util/any/misc/any_cast.cc: Test std::any_cast with
+	function types.
+
 	* testsuite/20_util/variant/run.cc: Catch exception by reference to
 	prevent -Wcatch-value warning.
 

libstdc++-v3/include/std/any

@@ -532,16 +532,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _ValueType>
     inline const _ValueType* any_cast(const any* __any) noexcept
     {
-      if (__any)
-	return static_cast<_ValueType*>(__any_caster<_ValueType>(__any));
+      if constexpr (is_object_v<_ValueType>)
+	if (__any)
+	  return static_cast<_ValueType*>(__any_caster<_ValueType>(__any));
       return nullptr;
     }
 
   template<typename _ValueType>
     inline _ValueType* any_cast(any* __any) noexcept
     {
-      if (__any)
-	return static_cast<_ValueType*>(__any_caster<_ValueType>(__any));
+      if constexpr (is_object_v<_ValueType>)
+	if (__any)
+	  return static_cast<_ValueType*>(__any_caster<_ValueType>(__any));
       return nullptr;
     }
   // @}

libstdc++-v3/testsuite/20_util/any/misc/any_cast.cc

@@ -20,6 +20,7 @@
 
 #include <any>
 #include <string>
+#include <utility>
 #include <cstring>
 #include <testsuite_hooks.h>
 
@@ -121,6 +122,38 @@ void test05()
   VERIFY( p == nullptr );
 }
 
+void test06()
+{
+  // The contained value of a std::any is always an object type,
+  // but std::any_cast does not forbid checking for function types.
+
+  any a(1);
+  void (*p1)() = any_cast<void()>(&a);
+  VERIFY( p1 == nullptr );
+  int (*p2)(int) = any_cast<int(int)>(&a);
+  VERIFY( p2 == nullptr );
+  int (*p3)() = any_cast<int()>(&std::as_const(a));
+  VERIFY( p3 == nullptr );
+
+  try {
+    any_cast<int(&)()>(a);
+    VERIFY( false );
+  } catch (const std::bad_any_cast&) {
+  }
+
+  try {
+    any_cast<int(&)()>(std::move(a));
+    VERIFY( false );
+  } catch (const std::bad_any_cast&) {
+  }
+
+  try {
+    any_cast<int(&)()>(std::as_const(a));
+    VERIFY( false );
+  } catch (const std::bad_any_cast&) {
+  }
+}
+
 int main()
 {
   test01();
@@ -128,4 +161,5 @@ int main()
   test03();
   test04();
   test05();
+  test06();
 }