Cleaup of requirements for optional. While researching LWG3196, I realized that optional did not reject 'const in_place_t' like it should. Added a test as well, and a check for arrays (which were already disallowed, but now we get a better error message). Should not affect anyone's code.

llvm-svn: 356918
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 36db4898740f21ddb9761815729266c2f5f3672b
diff --git a/include/optional b/include/optional
index 7c136ae..1fc752e 100644
--- a/include/optional
+++ b/include/optional
@@ -592,7 +592,7 @@
 
 private:
      // Disable the reference extension using this static assert.
-    static_assert(!is_same_v<value_type, in_place_t>,
+    static_assert(!is_same_v<__uncvref_t<value_type>, in_place_t>,
         "instantiation of optional with in_place_t is ill-formed");
     static_assert(!is_same_v<__uncvref_t<value_type>, nullopt_t>,
         "instantiation of optional with nullopt_t is ill-formed");
@@ -600,6 +600,8 @@
         "instantiation of optional with a reference type is ill-formed");
     static_assert(is_destructible_v<value_type>,
         "instantiation of optional with a non-destructible type is ill-formed");
+    static_assert(!is_array_v<value_type>,
+        "instantiation of optional with an array type is ill-formed");
 
     // LWG2756: conditionally explicit conversion from _Up
     struct _CheckOptionalArgsConstructor {