Add type unification as part of typecheck.

Rust must examine each usage of a name and unify their types. For example:

let mut x;
x = 1

This means the declaration is determined to be an inference variable then
the assignment can be resolved to an Integer TyTy which can be combined
as part of the rules to now make the let x decl be an i32.

1 files changed, 8 insertions, 4 deletions

diff --git a/gcc/rust/backend/rust-compile-context.h b/gcc/rust/backend/rust-compile-context.h
index f890678..1924b52 100644
--- a/gcc/rust/backend/rust-compile-context.h
+++ b/gcc/rust/backend/rust-compile-context.h
@@ -205,9 +205,13 @@ public:
 
   virtual ~TyTyResolveCompile () {}
 
-  void visit (TyTy::FnType &type) { gcc_unreachable (); }
+  void visit (TyTy::UnitType &type) override { gcc_unreachable (); }
 
-  void visit (TyTy::BoolType &type)
+  void visit (TyTy::InferType &type) override { gcc_unreachable (); }
+
+  void visit (TyTy::FnType &type) override { gcc_unreachable (); }
+
+  void visit (TyTy::BoolType &type) override
   {
     ::Btype *compiled_type = nullptr;
     bool ok = ctx->lookup_compiled_types (type.get_ref (), &compiled_type);
@@ -215,7 +219,7 @@ public:
     translated = compiled_type;
   }
 
-  void visit (TyTy::IntType &type)
+  void visit (TyTy::IntType &type) override
   {
     printf ("type [%s] has ref: %u\n", type.as_string ().c_str (),
 	    type.get_ref ());
@@ -226,7 +230,7 @@ public:
     translated = compiled_type;
   }
 
-  void visit (TyTy::UintType &type)
+  void visit (TyTy::UintType &type) override
   {
     ::Btype *compiled_type = nullptr;
     bool ok = ctx->lookup_compiled_types (type.get_ref (), &compiled_type);