Add hir lowering of closure expressions

In the AST we have ClosureExprInner and ClosureExprInnerTyped the first
is the closure expression of the form:

    let closure_inferred  = |i| i + 1;

The second is of the form:

    let closure_annotated = |i: i32| -> i32 { i + 1 };

Both of these can be seguared into a single HIR::ClosureExpr with an
optional return type and parameter types.

Addresses #195

3 files changed, 9 insertions, 6 deletions

diff --git a/gcc/rust/backend/rust-compile-block.h b/gcc/rust/backend/rust-compile-block.h
index cdd17f1..8f62f45 100644
--- a/gcc/rust/backend/rust-compile-block.h
+++ b/gcc/rust/backend/rust-compile-block.h
@@ -57,8 +57,7 @@ public:
   // Empty visit for unused Expression HIR nodes.
   void visit (HIR::PathInExpression &) override {}
   void visit (HIR::QualifiedPathInExpression &) override {}
-  void visit (HIR::ClosureExprInner &) override {}
-  void visit (HIR::ClosureExprInnerTyped &) override {}
+  void visit (HIR::ClosureExpr &) override {}
   void visit (HIR::StructExprFieldIdentifier &) override {}
   void visit (HIR::StructExprFieldIdentifierValue &) override {}
   void visit (HIR::StructExprFieldIndexValue &) override {}
@@ -146,8 +145,7 @@ public:
   // Empty visit for unused Expression HIR nodes.
   void visit (HIR::PathInExpression &) override {}
   void visit (HIR::QualifiedPathInExpression &) override {}
-  void visit (HIR::ClosureExprInner &) override {}
-  void visit (HIR::ClosureExprInnerTyped &) override {}
+  void visit (HIR::ClosureExpr &) override {}
   void visit (HIR::StructExprFieldIdentifier &) override {}
   void visit (HIR::StructExprFieldIdentifierValue &) override {}
   void visit (HIR::StructExprFieldIndexValue &) override {}
diff --git a/gcc/rust/backend/rust-compile-expr.cc b/gcc/rust/backend/rust-compile-expr.cc
index 9ff2be6..d66aa5d 100644
--- a/gcc/rust/backend/rust-compile-expr.cc
+++ b/gcc/rust/backend/rust-compile-expr.cc
@@ -2798,5 +2798,11 @@ CompileExpr::visit (HIR::ArrayIndexExpr &expr)
 						   expr.get_locus ());
 }
 
+void
+CompileExpr::visit (HIR::ClosureExpr &expr)
+{
+  gcc_unreachable ();
+}
+
 } // namespace Compile
 } // namespace Rust
diff --git a/gcc/rust/backend/rust-compile-expr.h b/gcc/rust/backend/rust-compile-expr.h
index f5cb06d..fee2ba7 100644
--- a/gcc/rust/backend/rust-compile-expr.h
+++ b/gcc/rust/backend/rust-compile-expr.h
@@ -67,10 +67,9 @@ public:
   void visit (HIR::RangeToExpr &expr) override;
   void visit (HIR::RangeFullExpr &expr) override;
   void visit (HIR::RangeFromToInclExpr &expr) override;
+  void visit (HIR::ClosureExpr &expr) override;
 
   // TODO
-  void visit (HIR::ClosureExprInner &) override {}
-  void visit (HIR::ClosureExprInnerTyped &) override {}
   void visit (HIR::ErrorPropagationExpr &) override {}
   void visit (HIR::RangeToInclExpr &) override {}
   void visit (HIR::ForLoopExpr &) override {}