Emit a non-implicit default constructor as explicit, closes #398

Author: hsutter

regression-tests/test-results/pure2-requires-clauses.cpp

@@ -23,7 +23,7 @@ template<typename T, typename U>
     requires( std::is_same_v<T,int> 
               && std::is_same_v<U,int> )
 class X {
-    public: X();
+    public: explicit X();
 
     public: X(X const&) = delete; /* No 'that' constructor, suppress copy */
     public: auto operator=(X const&) -> void = delete;

regression-tests/test-results/pure2-types-basics.cpp

@@ -42,7 +42,7 @@ class myclass {
 
 
 #line 27 "pure2-types-basics.cpp2"
-    public: myclass();
+    public: explicit myclass();
 
 
 #line 34 "pure2-types-basics.cpp2"

regression-tests/test-results/pure2-types-ordering-via-meta-functions.cpp

@@ -73,7 +73,7 @@ class mystruct {
 public: auto operator=(mystruct const& that) -> mystruct& ;
 public: mystruct(mystruct&& that);
 public: auto operator=(mystruct&& that) -> mystruct& ;
-public: mystruct();
+public: explicit mystruct();
 
 #line 19 "pure2-types-ordering-via-meta-functions.cpp2"
 };

regression-tests/test-results/pure2-types-that-parameters.cpp

@@ -17,7 +17,7 @@ class myclass;
 #line 2 "pure2-types-that-parameters.cpp2"
 class myclass {
 
-    public: myclass();
+    public: explicit myclass();
 
     public: myclass(myclass const& that);
 

regression-tests/test-results/pure2-types-value-types-via-meta-functions.cpp

@@ -34,7 +34,7 @@ public: widget(widget const& that);
 public: auto operator=(widget const& that) -> widget& ;
 public: widget(widget&& that);
 public: auto operator=(widget&& that) -> widget& ;
-public: widget();
+public: explicit widget();
 
 #line 5 "pure2-types-value-types-via-meta-functions.cpp2"
 };
@@ -50,7 +50,7 @@ public: w_widget(w_widget const& that);
 public: auto operator=(w_widget const& that) -> w_widget& ;
 public: w_widget(w_widget&& that);
 public: auto operator=(w_widget&& that) -> w_widget& ;
-public: w_widget();
+public: explicit w_widget();
 
 #line 10 "pure2-types-value-types-via-meta-functions.cpp2"
 };
@@ -66,7 +66,7 @@ public: p_widget(p_widget const& that);
 public: auto operator=(p_widget const& that) -> p_widget& ;
 public: p_widget(p_widget&& that);
 public: auto operator=(p_widget&& that) -> p_widget& ;
-public: p_widget();
+public: explicit p_widget();
 
 #line 15 "pure2-types-value-types-via-meta-functions.cpp2"
 };

regression-tests/test-results/version

@@ -1,5 +1,5 @@
 
-cppfront compiler v0.2.1   Build 8515:0547
+cppfront compiler v0.2.1   Build 8515:0551
 Copyright(c) Herb Sutter   All rights reserved
 
 SPDX-License-Identifier: CC-BY-NC-ND-4.0

source/build.info

@@ -1 +1 @@
-"8515:0547"
+"8515:0551"

source/cppfront.cpp

@@ -5262,8 +5262,8 @@ class cppfront
                         break;default:
                             if (
                                 func->is_constructor()
+                                && (func->is_default_constructor() || func->parameters->ssize() == 2)
                                 && !func->is_constructor_with_that()
-                                && func->parameters->ssize() == 2
                                 && generating_assignment_from != &n
                                 )
                             {