fix(sema): extend implicit else branch to containing statement

Author: JohelEGP

regression-tests/pure2-last-use.cpp2

@@ -79,6 +79,15 @@ issue_857_3: @struct type = {
   f: (move this) = _ = f_inout(i);
 }
 
+issue_884: () = {
+  x := new<int>(0);
+  if true { }
+  {
+    { f_inout(x); }
+    f_copy(x);
+  }
+}
+
 issue_888: (copy r: std::string, copy size: int) = {
   // ...
   _ = r.size();

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

@@ -20,7 +20,7 @@ class issue_857_2;
 class issue_857_3;
 
 
-#line 94 "pure2-last-use.cpp2"
+#line 103 "pure2-last-use.cpp2"
 class my_string;
 
 
@@ -88,12 +88,15 @@ class issue_857_3 {
   public: auto f() && -> void;
 };
 
+auto issue_884() -> void;
+
+#line 91 "pure2-last-use.cpp2"
 auto issue_888(std::string r, int size) -> void;
 
-#line 88 "pure2-last-use.cpp2"
+#line 97 "pure2-last-use.cpp2"
 auto draw() -> void;
 
-#line 94 "pure2-last-use.cpp2"
+#line 103 "pure2-last-use.cpp2"
 class my_string {
   public: std::string string; 
   public: std::size_t size {CPP2_UFCS(size)(string)}; 
@@ -188,6 +191,15 @@ int gi {0};
   auto issue_857_3::f() && -> void { static_cast<void>(f_inout(std::move(*this).i));  }
 
 #line 82 "pure2-last-use.cpp2"
+auto issue_884() -> void{
+  auto x {cpp2_new<int>(0)}; 
+  if (true) {}
+  {
+    {f_inout(x); }
+    f_copy(std::move(x));
+  }
+}
+
 auto issue_888(std::string r, int size) -> void{
   // ...
   static_cast<void>(CPP2_UFCS_MOVE(size)(std::move(r)));
@@ -200,10 +212,10 @@ auto draw() -> void{
   static_cast<void>(CPP2_UFCS_MOVE(vertex)((std::move(pos))));
 }
 
-#line 99 "pure2-last-use.cpp2"
+#line 108 "pure2-last-use.cpp2"
 auto main(int const argc_, char** argv_) -> int{
   auto const args = cpp2::make_args(argc_, argv_); 
-#line 100 "pure2-last-use.cpp2"
+#line 109 "pure2-last-use.cpp2"
   issue_683(args);
   issue_847_2(std::vector<std::unique_ptr<int>>());
 }

source/sema.h

@@ -1882,11 +1882,15 @@ class sema
         ++scope_depth;
     }
 
-    auto end(selection_statement_node const&, int) -> void
+    auto end(selection_statement_node const& s, int) -> void
     {
         symbols.emplace_back( scope_depth, selection_sym{ false, active_selections.back() } );
         active_selections.pop_back();
-        --scope_depth;
+        //  Extend the scope of an implicit else branch
+        //  to the closing brace that contains it.
+        if (s.false_branch->position() != source_position(0, 0)) {
+            --scope_depth;
+        }
     }
 
     auto kind_of(compound_statement_node const& n)
@@ -1922,6 +1926,18 @@ class sema
 
     auto end(compound_statement_node const& n, int) -> void
     {
+        //  Pop an implicit 'else' branch.
+        if (auto s = std::find_if(
+                         symbols.rbegin(),
+                         symbols.rend(),
+                         [=](symbol s) {
+                             return s.depth == scope_depth - 1;
+                         });
+            s == symbols.rend()
+            || std::get_if<symbol::selection>(&s->sym)
+            ) {
+            --scope_depth;
+        }
         symbols.emplace_back(
             scope_depth,
             compound_sym{ false, &n, kind_of(n) }