Make deferred initialization of std::array work correctly, closes #564

Also fixed a build break that slipped in a couple of hours ago for GCC and Clang (from inadvertently using an incomplete type, which MSVC didn't diagnose and I hadn't re-run the GCC and Clang builds)

Author: hsutter

include/cpp2util.h

@@ -566,8 +566,7 @@ class deferred_init {
    ~deferred_init() noexcept       { destroy(); }
     auto value()    noexcept -> T& { Default.expects(init);  return t(); }
 
-    auto construct     (auto&& ...args) -> void { Default.expects(!init);  new (&data) T(CPP2_FORWARD(args)...);  init = true; }
-    auto construct_list(auto&& ...args) -> void { Default.expects(!init);  new (&data) T{CPP2_FORWARD(args)...};  init = true; }
+    auto construct(auto&& ...args) -> void { Default.expects(!init);  new (&data) T{CPP2_FORWARD(args)...};  init = true; }
 };
 
 
@@ -636,33 +635,6 @@ class out {
         }
     }
 
-    auto construct_list(auto&& ...args) -> void {
-        if (has_t || called_construct()) {
-            if constexpr (requires { *t = T{CPP2_FORWARD(args)...}; }) {
-                Default.expects( t );
-                *t = T{CPP2_FORWARD(args)...};
-            }
-            else {
-                Default.expects(false, "attempted to copy assign, but copy assignment is not available");
-            }
-        }
-        else {
-            Default.expects( dt );
-            if (dt->init) {
-                if constexpr (requires { *t = T{CPP2_FORWARD(args)...}; }) {
-                    dt->value() = T{CPP2_FORWARD(args)...};
-                }
-                else {
-                    Default.expects(false, "attempted to copy assign, but copy assignment is not available");
-                }
-            }
-            else {
-                dt->construct(CPP2_FORWARD(args)...);
-                called_construct() = true;
-            }
-        }
-    }
-
     auto value() noexcept -> T& {
         if (has_t) {
             Default.expects( t );

regression-tests/test-results/clang-12/mixed-bugfix-for-cpp2-comment-cpp1-sequence.cpp.execution

@@ -0,0 +1 @@
+mixed-bugfix-for-cpp2-comment-cpp1-sequence.cpp

regression-tests/test-results/clang-12/mixed-bugfix-for-cpp2-comment-cpp1-sequence.cpp.output

@@ -1,5 +1,5 @@
 
-cppfront compiler v0.2.1   Build 8812:0920
+cppfront compiler v0.2.1   Build 8812:1229
 Copyright(c) Herb Sutter   All rights reserved
 
 SPDX-License-Identifier: CC-BY-NC-ND-4.0

regression-tests/test-results/gcc-13/mixed-bugfix-for-cpp2-comment-cpp1-sequence.cpp.execution

@@ -1 +1 @@
-"8812:0920"
+"8812:1229"

regression-tests/test-results/gcc-13/mixed-bugfix-for-cpp2-comment-cpp1-sequence.cpp.output

@@ -286,15 +286,15 @@ struct binary_expression_node
 
     //  API
     //
-    auto is_standalone_expression() const
+    auto lhs_is_id_expression() const
         -> bool
     {
-        return
-            my_expression
-            && my_expression->is_standalone_expression()
-            ;
+        return expr->is_id_expression();
     }
 
+    auto is_standalone_expression() const
+        -> bool;
+
     auto terms_size() const
         -> int
     {
@@ -547,6 +547,20 @@ binary_expression_node<Name, Term>::binary_expression_node() {
 }
 
 
+template<
+    String   Name,
+    typename Term
+>
+auto binary_expression_node<Name, Term>::is_standalone_expression() const
+    -> bool
+{
+    return
+        my_expression
+        && my_expression->is_standalone_expression()
+        ;
+}
+
+
 enum class passing_style { in=0, copy, inout, out, move, forward, invalid };
 auto to_passing_style(token const& t) -> passing_style {
     if (t.type() == lexeme::Identifier) {

regression-tests/test-results/msvc-2022/mixed-bugfix-for-cpp2-comment-cpp1-sequence.cpp.execution

@@ -1683,6 +1683,7 @@ class sema
     {
         if (
             n.is_standalone_expression()
+            && n.lhs_is_id_expression()
             && std::ssize(n.terms) > 0
             )
         {