fix(sema): improve heuristic to only move from last (implicit) this

Author: JohelEGP

regression-tests/pure2-last-use.cpp2

@@ -58,15 +58,21 @@ issue_857: type = {
   a: std::unique_ptr<int>;
   b: std::unique_ptr<int>;
   operator=: (out this, move that) = { }
-  operator=: (move this) = f_copy(a, this.b);
+  operator=: (move this) = {
+    f_inout(a);
+    f_copy(this.b);
+  }
   f: (move this) = f_copy(this);
   f: (move this, move that) = f_copy(this, that);
   g: (move this) = f_copy(this.a);
   g: (move this, move that) = f_copy(this.a, that.a);
   h: (inout this) = f_inout(a);
   i: (move this) = f_copy(a);
   j: (move this) = f_copy(a);
-  k: (move this) = f_copy(a, b);
+  k: (move this) = {
+    f_inout(a);
+    f_copy(b);
+  }
   l: (move this) = k();
   m: (move this) = this.k();
   n: (_) = { }
@@ -85,15 +91,15 @@ issue_857: type = {
     f_copy(a);
   }
   p2: (move this) = {
-  //f_inout(a); // FIXME Moves `a`.
+    f_inout(a);
     f_copy(this);
   }
   p3: (move this) = {
   //f_inout(this); // FIXME Moves `this`.
     f_copy(a);
   }
   q: (move this) = {
-  //m(); // FIXME Moves implicit `this`.
+    h();
     n();
   }
 // FIXME
@@ -171,7 +177,7 @@ draw: () = {
 union: type = {
   destroy: (inout this) = { }
   operator=: (move this) = {
-    // destroy(); FIXME Discarding `this` still moves it here.
+    destroy();
     _ = this;
   }
 }

regression-tests/test-results/pure2-last-use.cpp

@@ -12,23 +12,23 @@
 class issue_857;
 
 
-#line 117 "pure2-last-use.cpp2"
+#line 123 "pure2-last-use.cpp2"
 class issue_857_2;
 
 
-#line 122 "pure2-last-use.cpp2"
+#line 128 "pure2-last-use.cpp2"
 class issue_857_3;
 
 
-#line 127 "pure2-last-use.cpp2"
+#line 133 "pure2-last-use.cpp2"
 class issue_869;
 
 
-#line 171 "pure2-last-use.cpp2"
+#line 177 "pure2-last-use.cpp2"
 class cpp2_union;
 
 
-#line 179 "pure2-last-use.cpp2"
+#line 185 "pure2-last-use.cpp2"
 class my_string;
 
 
@@ -71,6 +71,8 @@ class issue_857 {
 #line 60 "pure2-last-use.cpp2"
   public: auto operator=(issue_857&& that) noexcept -> issue_857& ;
   public: ~issue_857() noexcept;
+
+#line 65 "pure2-last-use.cpp2"
   public: auto f() && -> void;
   public: auto f(issue_857&& that) && -> void;
   public: auto g() && -> void;
@@ -79,6 +81,8 @@ class issue_857 {
   public: auto i() && -> void;
   public: auto j() && -> void;
   public: auto k() && -> void;
+
+#line 76 "pure2-last-use.cpp2"
   public: auto l() && -> void;
   public: auto m() && -> void;
   public: static auto n([[maybe_unused]] auto const& unnamed_param_1) -> void;
@@ -90,19 +94,19 @@ class issue_857 {
   public: auto o4() && -> void;
   public: auto p0() && -> void;
 
-#line 83 "pure2-last-use.cpp2"
+#line 89 "pure2-last-use.cpp2"
   public: auto p1() && -> void;
 
-#line 87 "pure2-last-use.cpp2"
+#line 93 "pure2-last-use.cpp2"
   public: auto p2() && -> void;
 
-#line 91 "pure2-last-use.cpp2"
+#line 97 "pure2-last-use.cpp2"
   public: auto p3() && -> void;
 
-#line 95 "pure2-last-use.cpp2"
+#line 101 "pure2-last-use.cpp2"
   public: auto q() && -> void;
 
-#line 99 "pure2-last-use.cpp2"
+#line 105 "pure2-last-use.cpp2"
 // FIXME
 //z: (move this, move that) = {
 ///*f */      if true { f_copy(this); }
@@ -146,24 +150,24 @@ public: issue_869(issue_869&& that) noexcept;
 public: auto operator=(issue_869 const& that) -> issue_869& ;
 public: auto operator=(issue_869&& that) noexcept -> issue_869& ;
 
-#line 129 "pure2-last-use.cpp2"
+#line 135 "pure2-last-use.cpp2"
 };
 
 auto issue_884_3() -> void;
 
-#line 141 "pure2-last-use.cpp2"
+#line 147 "pure2-last-use.cpp2"
 auto issue_884() -> void;
 
-#line 150 "pure2-last-use.cpp2"
+#line 156 "pure2-last-use.cpp2"
 auto issue_884_2() -> void;
 
-#line 159 "pure2-last-use.cpp2"
+#line 165 "pure2-last-use.cpp2"
 auto issue_888(std::string r, int size) -> void;
 
-#line 165 "pure2-last-use.cpp2"
+#line 171 "pure2-last-use.cpp2"
 auto draw() -> void;
 
-#line 171 "pure2-last-use.cpp2"
+#line 177 "pure2-last-use.cpp2"
 class cpp2_union {
   public: auto destroy() & -> void;
   public: ~cpp2_union() noexcept;
@@ -172,7 +176,7 @@ class cpp2_union {
   public: auto operator=(cpp2_union const&) -> void = delete;
 
 
-#line 177 "pure2-last-use.cpp2"
+#line 183 "pure2-last-use.cpp2"
 };
 
 class my_string {
@@ -252,15 +256,21 @@ auto f_copy([[maybe_unused]] auto ...unnamed_param_1) -> void{}
                                        b = std::move(that).b;
                                        return *this; }
 #line 61 "pure2-last-use.cpp2"
-  issue_857::~issue_857() noexcept { f_copy(std::move(*this).a, std::move((*this)).b);  }
+  issue_857::~issue_857() noexcept{
+    f_inout(a);
+    f_copy(std::move((*this)).b);
+  }
   auto issue_857::f() && -> void { f_copy(std::move((*this)));  }
   auto issue_857::f(issue_857&& that) && -> void { f_copy(std::move((*this)), std::move(that));  }
   auto issue_857::g() && -> void { f_copy(std::move((*this)).a);  }
   auto issue_857::g(issue_857&& that) && -> void { f_copy(std::move((*this)).a, std::move(that).a);  }
   auto issue_857::h() & -> void { f_inout(a);  }
   auto issue_857::i() && -> void { f_copy(std::move(*this).a);  }
   auto issue_857::j() && -> void { f_copy(std::move(*this).a);  }
-  auto issue_857::k() && -> void { f_copy(std::move(*this).a, std::move(*this).b);  }
+  auto issue_857::k() && -> void{
+    f_inout(a);
+    f_copy(std::move(*this).b);
+  }
   auto issue_857::l() && -> void { std::move(*this).k();  }
   auto issue_857::m() && -> void { CPP2_UFCS(k)(std::move((*this)));  }
   auto issue_857::n([[maybe_unused]] auto const& unnamed_param_1) -> void{}
@@ -269,7 +279,7 @@ auto f_copy([[maybe_unused]] auto ...unnamed_param_1) -> void{}
   auto issue_857::o1() && -> void { CPP2_UFCS(n)(std::move((*this)));  }
   auto issue_857::o2() && -> void { CPP2_UFCS(n)(0);  }
   auto issue_857::o3() && -> void { std::move(*this).n(0);  }
-  auto issue_857::o4() && -> void { std::move(*this).n(std::move((*this)));  }
+  auto issue_857::o4() && -> void { n(std::move((*this)));  }
   auto issue_857::p0() && -> void{
     f_inout(a);
     f_copy(std::move((*this)).a);
@@ -279,22 +289,22 @@ auto f_copy([[maybe_unused]] auto ...unnamed_param_1) -> void{}
     f_copy(std::move(*this).a);
   }
   auto issue_857::p2() && -> void{
-  //f_inout(a); // FIXME Moves `a`.
+    f_inout(a);
     f_copy(std::move((*this)));
   }
   auto issue_857::p3() && -> void{
   //f_inout(this); // FIXME Moves `this`.
     f_copy(std::move(*this).a);
   }
   auto issue_857::q() && -> void{
-  //m(); // FIXME Moves implicit `this`.
+    h();
     std::move(*this).n();
   }
 
-#line 121 "pure2-last-use.cpp2"
+#line 127 "pure2-last-use.cpp2"
 int gi {0}; 
 
-#line 124 "pure2-last-use.cpp2"
+#line 130 "pure2-last-use.cpp2"
   auto issue_857_3::f() && -> void { static_cast<void>(f_inout(std::move(*this).i));  }
 
 
@@ -335,7 +345,7 @@ issue_869::issue_869(issue_869 const& that)
   if (CPP2_UFCS(is_i)(std::move(that))) {set_i(CPP2_UFCS(i)(std::move(that)));}
         return *this;
   }
-#line 131 "pure2-last-use.cpp2"
+#line 137 "pure2-last-use.cpp2"
 auto issue_884_3() -> void{
   auto x {cpp2_new<int>(0)}; 
   if (true) {}
@@ -376,17 +386,17 @@ auto draw() -> void{
   static_cast<void>(CPP2_UFCS_MOVE(vertex)((std::move(pos))));
 }
 
-#line 172 "pure2-last-use.cpp2"
+#line 178 "pure2-last-use.cpp2"
   auto cpp2_union::destroy() & -> void{}
   cpp2_union::~cpp2_union() noexcept{
-    // destroy(); FIXME Discarding `this` still moves it here.
+    destroy();
     static_cast<void>(std::move((*this)));
   }
 
-#line 184 "pure2-last-use.cpp2"
+#line 190 "pure2-last-use.cpp2"
 auto main(int const argc_, char** argv_) -> int{
   auto const args = cpp2::make_args(argc_, argv_); 
-#line 185 "pure2-last-use.cpp2"
+#line 191 "pure2-last-use.cpp2"
   issue_683(args);
   issue_847_2(std::vector<std::unique_ptr<int>>());
 }

source/sema.h

@@ -343,21 +343,22 @@ class sema
     //
     auto get_declaration_of(
         token const* t,
-        bool         look_beyond_current_function = false
-    )
+        bool         look_beyond_current_function = false,
+        bool         look_up_to_type              = false
+    ) const
         -> declaration_sym const*
     {
         if (!t) {
             return {};
         }
-        return get_declaration_of(*t, look_beyond_current_function);
+        return get_declaration_of(*t, look_beyond_current_function, look_up_to_type);
     }
 
     auto get_declaration_of(
         token const& t,
         bool         look_beyond_current_function = false,
         bool         look_up_to_type              = false
-    )
+    ) const
         -> declaration_sym const*
     {
         //  First find the position the query is coming from
@@ -367,7 +368,13 @@ class sema
             i != symbols.cend()
             && (
                 !i->get_token()
-                || final_position[i->get_token()] < final_position[&t]
+                || [&]() {
+                       auto lhs = final_position.find(i->get_token());
+                       auto rhs = final_position.find(&t);
+                       return lhs == final_position.end()
+                              || rhs == final_position.end()
+                              || lhs->second < rhs->second;
+                   }()
                 )
             )
         {
@@ -756,7 +763,20 @@ class sema
                 assert (sym.identifier);
 
                 //  If we find a use of this identifier
-                if (*sym.identifier == *id)
+                if (
+                    *sym.identifier == *id
+                    || (
+                        in_type_scope
+                        && (
+                            *sym.identifier == "this"
+                            || [&]() {
+                                   auto decl = get_declaration_of(sym.get_token(), true, true);
+                                   return decl
+                                          && decl->declaration->parent_is_type();
+                               }()
+                            )
+                        )
+                    )
                 {
                     if (
                         !found