Merge #894

894: Update name-resolution to build up canonical-path with the crate-name r=philberty a=philberty

The name resolver there are two types of canonical-path object.
    
1. The relative canonical path to a type for name resolution
2. The full canonical-path including the crate-name (this-was-missing)
    
The lack of the crate-name being present in the canonical-path meant the
symbol mangling system was required to append it where appropriate but this
was going to be too messy to handle all cases. Such as module blocks
containing impl blocks requires a ```prefix::<impl crate::path>::item``` and
similarly for trait impl blocks.

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

1 files changed, 43 insertions, 14 deletions

diff --git a/gcc/rust/resolve/rust-ast-resolve.cc b/gcc/rust/resolve/rust-ast-resolve.cc
index a34e631..96524d2 100644
--- a/gcc/rust/resolve/rust-ast-resolve.cc
+++ b/gcc/rust/resolve/rust-ast-resolve.cc
@@ -313,6 +313,13 @@ NameResolution::Resolve (AST::Crate &crate)
 void
 NameResolution::go (AST::Crate &crate)
 {
+  // lookup current crate name
+  CrateNum cnum = mappings->get_current_crate ();
+  std::string crate_name;
+  bool ok = mappings->get_crate_name (cnum, crate_name);
+  rust_assert (ok);
+
+  // setup the ribs
   NodeId scope_node_id = crate.get_node_id ();
   resolver->get_name_scope ().push (scope_node_id);
   resolver->get_type_scope ().push (scope_node_id);
@@ -321,16 +328,25 @@ NameResolution::go (AST::Crate &crate)
   resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
   resolver->push_new_label_rib (resolver->get_type_scope ().peek ());
 
-  // first gather the top-level namespace names then we drill down
+  // get the root segment
+  CanonicalPath crate_prefix
+    = CanonicalPath::new_seg (scope_node_id, crate_name);
+  crate_prefix.set_crate_num (cnum);
+
+  // first gather the top-level namespace names then we drill down so this
+  // allows for resolving forward declarations since an impl block might have
+  // a Self type Foo which is defined after the impl block for example.
   for (auto it = crate.items.begin (); it != crate.items.end (); it++)
-    ResolveTopLevel::go (it->get ());
+    ResolveTopLevel::go (it->get (), CanonicalPath::create_empty (),
+			 crate_prefix);
 
+  // FIXME remove this
   if (saw_errors ())
     return;
 
   // next we can drill down into the items and their scopes
   for (auto it = crate.items.begin (); it != crate.items.end (); it++)
-    ResolveItem::go (it->get ());
+    ResolveItem::go (it->get (), CanonicalPath::create_empty (), crate_prefix);
 }
 
 // rust-ast-resolve-expr.h
@@ -349,17 +365,19 @@ ResolveExpr::visit (AST::BlockExpr &expr)
   for (auto &s : expr.get_statements ())
     {
       if (s->is_item ())
-	ResolveStmt::go (s.get (), s->get_node_id ());
+	ResolveStmt::go (s.get (), s->get_node_id (), prefix, canonical_prefix,
+			 CanonicalPath::create_empty ());
     }
 
   for (auto &s : expr.get_statements ())
     {
       if (!s->is_item ())
-	ResolveStmt::go (s.get (), s->get_node_id ());
+	ResolveStmt::go (s.get (), s->get_node_id (), prefix, canonical_prefix,
+			 CanonicalPath::create_empty ());
     }
 
   if (expr.has_tail_expr ())
-    ResolveExpr::go (expr.get_tail_expr ().get (), expr.get_node_id ());
+    resolve_expr (expr.get_tail_expr ().get (), expr.get_node_id ());
 
   resolver->get_name_scope ().pop ();
   resolver->get_type_scope ().pop ();
@@ -371,13 +389,15 @@ ResolveExpr::visit (AST::BlockExpr &expr)
 void
 ResolveStructExprField::visit (AST::StructExprFieldIdentifierValue &field)
 {
-  ResolveExpr::go (field.get_value ().get (), field.get_node_id ());
+  ResolveExpr::go (field.get_value ().get (), field.get_node_id (), prefix,
+		   canonical_prefix);
 }
 
 void
 ResolveStructExprField::visit (AST::StructExprFieldIndexValue &field)
 {
-  ResolveExpr::go (field.get_value ().get (), field.get_node_id ());
+  ResolveExpr::go (field.get_value ().get (), field.get_node_id (), prefix,
+		   canonical_prefix);
 }
 
 void
@@ -386,7 +406,7 @@ ResolveStructExprField::visit (AST::StructExprFieldIdentifier &field)
   AST::IdentifierExpr expr (field.get_field_name (), {}, field.get_locus ());
   expr.set_node_id (field.get_node_id ());
 
-  ResolveExpr::go (&expr, field.get_node_id ());
+  ResolveExpr::go (&expr, field.get_node_id (), prefix, canonical_prefix);
 }
 
 // rust-ast-resolve-type.h
@@ -746,7 +766,12 @@ void
 ResolveType::visit (AST::ArrayType &type)
 {
   type.get_elem_type ()->accept_vis (*this);
-  ResolveExpr::go (type.get_size_expr ().get (), type.get_node_id ());
+  // FIXME
+  // the capacity expr can contain block-expr with functions but these should be
+  // folded via constexpr code
+  ResolveExpr::go (type.get_size_expr ().get (), type.get_node_id (),
+		   CanonicalPath::create_empty (),
+		   CanonicalPath::create_empty ());
 }
 
 void
@@ -771,15 +796,19 @@ ResolveType::visit (AST::TraitObjectType &type)
 // rust-ast-resolve-item.h
 
 void
-ResolveItem::resolve_impl_item (AST::TraitImplItem *item)
+ResolveItem::resolve_impl_item (AST::TraitImplItem *item,
+				const CanonicalPath &prefix,
+				const CanonicalPath &canonical_prefix)
 {
-  ResolveImplItems::go (item);
+  ResolveImplItems::go (item, prefix, canonical_prefix);
 }
 
 void
-ResolveItem::resolve_impl_item (AST::InherentImplItem *item)
+ResolveItem::resolve_impl_item (AST::InherentImplItem *item,
+				const CanonicalPath &prefix,
+				const CanonicalPath &canonical_prefix)
 {
-  ResolveImplItems::go (item);
+  ResolveImplItems::go (item, prefix, canonical_prefix);
 }
 
 void