Add *value meta functions, and don't mark copy/move ctors explicit, closes hsutter#375

Generated code now doesn't get tacked together as a very long emitted line - which is legal code, but isn't visually pleasing or readable. This matters more in this commit now that we have meta functions that generate multiple functions in the same type.

Author: hsutter

regression-tests/pure2-types-value-types-via-meta-functions.cpp2

@@ -0,0 +1,35 @@
+
+widget: @value type = {
+    val: int = 0;
+    operator=: (out this, i: int) = { val = i; }
+}
+
+w_widget: @weakly_ordered_value type = {
+    val: int = 0;
+    operator=: (out this, i: int) = { val = i; }
+}
+
+p_widget: @partially_ordered_value type = {
+    val: int = 0;
+    operator=: (out this, i: int) = { val = i; }
+}
+
+main: () = {
+    test<widget>();
+    test<w_widget>();
+    test<p_widget>();
+}
+
+test: <T> () = {
+    //  should be default constructible
+    a: T = ();
+
+    //  widget should be comparable
+    b: T = 2;
+    if (a<b) {
+        std::cout << "less ";
+    }
+    else {
+        std::cout << "more ";
+    }
+}

regression-tests/test-results/clang-12/pure2-types-value-types-via-meta-functions.cpp.execution

@@ -0,0 +1 @@
+less less less 

regression-tests/test-results/clang-12/pure2-types-value-types-via-meta-functions.cpp.output

@@ -0,0 +1 @@
+less less less 

regression-tests/test-results/gcc-10/pure2-types-value-types-via-meta-functions.cpp.execution

@@ -0,0 +1 @@
+less less less 

regression-tests/test-results/gcc-10/pure2-types-value-types-via-meta-functions.cpp.output

@@ -0,0 +1 @@
+pure2-types-value-types-via-meta-functions.cpp

regression-tests/test-results/msvc-2022/pure2-types-value-types-via-meta-functions.cpp.execution

@@ -28,19 +28,22 @@ class Cyborg;
 #line 2 "pure2-types-inheritance.cpp2"
 class Human {
     public: virtual auto speak() const -> void = 0;
+
 public: virtual ~Human();
+
     public: Human() = default;
     public: Human(Human const&) = delete;
     public: auto operator=(Human const&) -> void = delete;
-
 #line 4 "pure2-types-inheritance.cpp2"
 };
 
 namespace N {
     template<int I> class Machine {
         public: explicit Machine(cpp2::in<std::string> id);
         public: virtual auto work() const -> void = 0;
+    
     public: virtual ~Machine();
+
         public: Machine(Machine const&) = delete;
         public: auto operator=(Machine const&) -> void = delete;
 
@@ -88,13 +91,15 @@ auto main() -> int;
 
 //=== Cpp2 function definitions =================================================
 
-#line 0 "pure2-types-inheritance.cpp2"
-Human::~Human(){}
 
+    
+    Human::~Human(){}
 #line 6 "pure2-types-inheritance.cpp2"
 namespace N {
 
-        template <int I> Machine<I>::Machine(cpp2::in<std::string> id){}template <int I> Machine<I>::~Machine(){}
+        template <int I> Machine<I>::Machine(cpp2::in<std::string> id){}
+        template <int I> 
+        Machine<I>::~Machine(){}
 
 #line 11 "pure2-types-inheritance.cpp2"
 }

regression-tests/test-results/msvc-2022/pure2-types-value-types-via-meta-functions.cpp.output

@@ -28,10 +28,11 @@ class my_integer {
     public: explicit my_integer(cpp2::in<int> val);
 #line 4 "pure2-types-ordering-via-meta-functions.cpp2"
     public: auto operator=(cpp2::in<int> val) -> my_integer& ;
+
 public: [[nodiscard]] auto operator<=>(my_integer const& that) const -> std::strong_ordering = default;
+
     public: my_integer(my_integer const&) = delete;
     public: auto operator=(my_integer const&) -> void = delete;
-
 #line 5 "pure2-types-ordering-via-meta-functions.cpp2"
 };
 
@@ -40,10 +41,11 @@ class case_insensitive_string {
     public: explicit case_insensitive_string(cpp2::in<std::string> val);
 #line 9 "pure2-types-ordering-via-meta-functions.cpp2"
     public: auto operator=(cpp2::in<std::string> val) -> case_insensitive_string& ;
+
 public: [[nodiscard]] auto operator<=>(case_insensitive_string const& that) const -> std::weak_ordering = default;
+
     public: case_insensitive_string(case_insensitive_string const&) = delete;
     public: auto operator=(case_insensitive_string const&) -> void = delete;
-
 #line 10 "pure2-types-ordering-via-meta-functions.cpp2"
 };
 
@@ -52,10 +54,11 @@ class person_in_family_tree {
     public: explicit person_in_family_tree(cpp2::in<int> parents);
 #line 14 "pure2-types-ordering-via-meta-functions.cpp2"
     public: auto operator=(cpp2::in<int> parents) -> person_in_family_tree& ;
+
 public: [[nodiscard]] auto operator<=>(person_in_family_tree const& that) const -> std::partial_ordering = default;
+
     public: person_in_family_tree(person_in_family_tree const&) = delete;
     public: auto operator=(person_in_family_tree const&) -> void = delete;
-
 #line 15 "pure2-types-ordering-via-meta-functions.cpp2"
 };
 

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

@@ -17,11 +17,11 @@ class myclass;
 #line 2 "pure2-types-smf-and-that-1-provide-everything.cpp2"
 class myclass {
 
-    public: explicit myclass(myclass const& that);
+    public: myclass(myclass const& that);
 
 
 #line 8 "pure2-types-smf-and-that-1-provide-everything.cpp2"
-    public: explicit myclass(myclass&& that);
+    public: myclass(myclass&& that);
 
 
 #line 13 "pure2-types-smf-and-that-1-provide-everything.cpp2"