fix(cpp1): account for initializers of this members

Author: JohelEGP

regression-tests/pure2-bugfix-for-default-constructor-this-initializer.cpp2

@@ -0,0 +1,13 @@
+base: type = {
+  public x: i32         = -1;
+  operator=: (out this) = { }
+  operator=: (out this, y: i32) = x = y;
+}
+derived: type = {
+  y: i32     = 2;
+  this: base = 42;
+}
+main: () = {
+  [[assert: derived().y == 2]]
+  [[assert: derived().x == 42]]
+}

regression-tests/test-results/pure2-bugfix-for-default-constructor-this-initializer.cpp

@@ -0,0 +1,70 @@
+
+#define CPP2_USE_MODULES         Yes
+
+//=== Cpp2 type declarations ====================================================
+
+
+#include "cpp2util.h"
+
+#line 1 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+class base;
+
+#line 6 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+class derived;
+
+
+//=== Cpp2 type definitions and function declarations ===========================
+
+#line 1 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+class base {
+         public: cpp2::i32 x {-1}; 
+  public: explicit base();
+  public: explicit base(cpp2::in<cpp2::i32> y);
+#line 4 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+  public: auto operator=(cpp2::in<cpp2::i32> y) -> base& ;
+
+  public: base(base const&) = delete; /* No 'that' constructor, suppress copy */
+  public: auto operator=(base const&) -> void = delete;
+#line 5 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+};
+
+struct derived_y_as_base { cpp2::i32 y; };
+#line 6 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+class derived: public derived_y_as_base, public base {
+public: explicit derived();
+
+  public: derived(derived const&) = delete; /* No 'that' constructor, suppress copy */
+  public: auto operator=(derived const&) -> void = delete;
+
+
+#line 9 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+};
+auto main() -> int;
+  
+
+//=== Cpp2 function definitions =================================================
+
+
+#line 3 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+  base::base(){}
+  base::base(cpp2::in<cpp2::i32> y)
+                                  : x{ y }
+#line 4 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+   {  }
+#line 4 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+  auto base::operator=(cpp2::in<cpp2::i32> y) -> base&  { 
+                                  x = y;
+                                  return *this;
+#line 4 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+   }
+
+  derived::derived()
+                          : derived_y_as_base{ 2 }
+                          , base{ 42 }{}
+
+#line 10 "pure2-bugfix-for-default-constructor-this-initializer.cpp2"
+auto main() -> int{
+  cpp2::Default.expects(derived().y==2, "");
+  cpp2::Default.expects(derived().x==42, "");
+}
+

regression-tests/test-results/pure2-bugfix-for-default-constructor-this-initializer.cpp2.output

@@ -0,0 +1,2 @@
+pure2-bugfix-for-default-constructor-this-initializer.cpp2... ok (all Cpp2, passes safety checks)
+

source/cppfront.cpp

@@ -4927,11 +4927,8 @@ class cppfront
             {
                 auto& decl = std::get<statement_node::declaration>(stmt->statement);
                 assert(decl);
-                assert(decl->name());
-                auto emit_as_base =
-                    decl->get_decl_if_type_scope_object_name_before_a_base_type(*decl->name());
 
-                if (emit_as_base) {
+                if (decl->emit_data_member_as_base()) {
                     printer.print_extra(
                         "\nstruct "
                             + print_to_string(*decl->parent_declaration->name())
@@ -5086,12 +5083,7 @@ class cppfront
 
                 //  First we'll encounter the base types == subobjects named "this"
                 //  and any data members declared before them that we push into private bases
-                assert(decl->name());
-                auto emit_as_base =
-                    decl->get_decl_if_type_scope_object_name_before_a_base_type(*decl->name())
-                    || decl->has_name("this")
-                    ;
-                if (emit_as_base)
+                if (decl->emit_as_base())
                 {
                     //  Do the sema check for these declarations here, because we're
                     //  handling them here instead of going through emit() for them

source/parse.h

@@ -22,6 +22,7 @@
 #include <memory>
 #include <variant>
 #include <iostream>
+#include <functional>
 
 
 namespace cpp2 {
@@ -2283,6 +2284,56 @@ struct declaration_node
     }
 
 
+    auto emit_data_member_as_base() const
+        -> bool
+    {
+        assert(name());
+        return get_decl_if_type_scope_object_name_before_a_base_type(*name());
+    }
+
+
+    auto emit_as_base() const
+        -> bool
+    {
+        return emit_data_member_as_base() || has_name("this");
+    }
+
+
+    auto should_add_default_constructor() const
+        -> bool
+    {
+        if (
+            !is_type()
+            || !initializer
+            || !initializer->is_compound()
+            )
+        {
+            return false;
+        }
+        
+        auto const any_statement = [&](auto pred) {
+            auto& statements = std::get<statement_node::compound>(initializer->statement)->statements;
+            return std::any_of
+            (
+                statements.begin(),
+                statements.end(),
+                [pred]( auto& stmt )
+                {
+                    const auto decl = std::get_if<statement_node::declaration>(&stmt->statement);
+                    return decl && std::invoke(pred, decl->get());
+                }
+            );
+        };
+
+        if ( any_statement( &declaration_node::is_constructor ) )
+        {
+            return false;
+        }
+
+        return any_statement( &declaration_node::emit_as_base );
+    }
+
+
     auto get_decl_if_type_scope_object_name_before_a_base_type( std::string_view s ) const
         -> declaration_node const*
     {