Merge #1611

1611: Initial state capture for closures r=philberty a=philberty

This patch set adds the initial support closure captures, move semantics are not
handled here. We track what variables are being captured by a closure during
name resolution so that when a VAR_DECL is resolved, we check if we are inside
a closure context node_id which is the same id as its associated rib id. So when
we resolve a name that resides in an outermost rib we can add this to set of 
node-id's that are captured by this closure.

There is a gap here for the case where we need to check if it is inside a nested
function and that function contains closures which could wrongly capture variables
in the enclosing function. This will also be a problem for nested functions in general.

Fixes #195

Co-authored-by: Philip Herron <philip.herron@embecosm.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/gcc/rust/backend/rust-compile-context.cc b/gcc/rust/backend/rust-compile-context.cc
index cb2addf6..0687398 100644
--- a/gcc/rust/backend/rust-compile-context.cc
+++ b/gcc/rust/backend/rust-compile-context.cc
@@ -142,5 +142,52 @@ Context::type_hasher (tree type)
   return hstate.end ();
 }
 
+void
+Context::push_closure_context (HirId id)
+{
+  auto it = closure_bindings.find (id);
+  rust_assert (it == closure_bindings.end ());
+
+  closure_bindings.insert ({id, {}});
+  closure_scope_bindings.push_back (id);
+}
+
+void
+Context::pop_closure_context ()
+{
+  rust_assert (!closure_scope_bindings.empty ());
+
+  HirId ref = closure_scope_bindings.back ();
+  closure_scope_bindings.pop_back ();
+  closure_bindings.erase (ref);
+}
+
+void
+Context::insert_closure_binding (HirId id, tree expr)
+{
+  rust_assert (!closure_scope_bindings.empty ());
+
+  HirId ref = closure_scope_bindings.back ();
+  closure_bindings[ref].insert ({id, expr});
+}
+
+bool
+Context::lookup_closure_binding (HirId id, tree *expr)
+{
+  if (closure_scope_bindings.empty ())
+    return false;
+
+  HirId ref = closure_scope_bindings.back ();
+  auto it = closure_bindings.find (ref);
+  rust_assert (it != closure_bindings.end ());
+
+  auto iy = it->second.find (id);
+  if (iy == it->second.end ())
+    return false;
+
+  *expr = iy->second;
+  return true;
+}
+
 } // namespace Compile
 } // namespace Rust