gccrs: Add lowering for if-let expressions

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-expr.cc
	(TypeCheckExpr::visit): Add implementation for IfLetExprConseqElse.
	* typecheck/rust-hir-type-check-expr.h:
	(TypeCheckExpr::visit): Remove stub implementation for IfLetExprConseqElse.
	* hir/rust-ast-lower-expr.cc
	(ASTLoweringExpr::visit): Lower IfLetExpr{,ConseqElse}.
	* hir/rust-ast-lower-expr.h:
	(ASTLoweringExpr::visit): Likewise.
	* hir/rust-ast-lower-block.h
	(ASTLoweringIfLetBlock::visit): Lower IfLetExprConseqElse.
	(ASTLoweringExprWithBlock::visit): Likewise.
	* hir/rust-ast-lower.cc
	(ASTLoweringIfLetBlock::visit): Lower IfLetExprConseqElse.
	* hir/tree/rust-hir-expr.h
	(IfLetExprConseqElse::IfLetExprConseqElse): Make constructor more general.
	(IfLetExprConseqElse::vis_else_block): Add.
	(IfLetExprConseqElse::get_else_block): Add.
	* resolve/rust-ast-resolve-expr.cc
	(ResolveExpr::visit): Add IfLetExprConseqElse visitor.
	* resolve/rust-ast-resolve-expr.h
	(ResolveExpr::visit): Add IfLetExprConseqElse visitor.

gcc/testsuite/ChangeLog:

	* rust/compile/if_let_expr.rs: Increase test coverage.

Signed-off-by: Owen Avery <powerboat9.gamer@gmail.com>

2 files changed, 32 insertions, 0 deletions

diff --git a/gcc/rust/resolve/rust-ast-resolve-expr.cc b/gcc/rust/resolve/rust-ast-resolve-expr.cc
index 339fd8a..41ce9c9 100644
--- a/gcc/rust/resolve/rust-ast-resolve-expr.cc
+++ b/gcc/rust/resolve/rust-ast-resolve-expr.cc
@@ -217,6 +217,37 @@ ResolveExpr::visit (AST::IfLetExpr &expr)
 }
 
 void
+ResolveExpr::visit (AST::IfLetExprConseqElse &expr)
+{
+  ResolveExpr::go (expr.get_value_expr ().get (), prefix, canonical_prefix);
+
+  NodeId scope_node_id = expr.get_node_id ();
+  resolver->get_name_scope ().push (scope_node_id);
+  resolver->get_type_scope ().push (scope_node_id);
+  resolver->get_label_scope ().push (scope_node_id);
+  resolver->push_new_name_rib (resolver->get_name_scope ().peek ());
+  resolver->push_new_type_rib (resolver->get_type_scope ().peek ());
+  resolver->push_new_label_rib (resolver->get_type_scope ().peek ());
+
+  // We know expr.get_patterns () has one pattern at most
+  // so there's no reason to handle it like an AltPattern.
+  std::vector<PatternBinding> bindings
+    = {PatternBinding (PatternBoundCtx::Product, std::set<Identifier> ())};
+
+  for (auto &pattern : expr.get_patterns ())
+    {
+      PatternDeclaration::go (pattern.get (), Rib::ItemType::Var, bindings);
+    }
+
+  ResolveExpr::go (expr.get_if_block ().get (), prefix, canonical_prefix);
+  ResolveExpr::go (expr.get_else_block ().get (), prefix, canonical_prefix);
+
+  resolver->get_name_scope ().pop ();
+  resolver->get_type_scope ().pop ();
+  resolver->get_label_scope ().pop ();
+}
+
+void
 ResolveExpr::visit (AST::BlockExpr &expr)
 {
   NodeId scope_node_id = expr.get_node_id ();
diff --git a/gcc/rust/resolve/rust-ast-resolve-expr.h b/gcc/rust/resolve/rust-ast-resolve-expr.h
index 7b0beaf..896617cc 100644
--- a/gcc/rust/resolve/rust-ast-resolve-expr.h
+++ b/gcc/rust/resolve/rust-ast-resolve-expr.h
@@ -51,6 +51,7 @@ public:
   void visit (AST::IfExpr &expr) override;
   void visit (AST::IfExprConseqElse &expr) override;
   void visit (AST::IfLetExpr &expr) override;
+  void visit (AST::IfLetExprConseqElse &expr) override;
   void visit (AST::BlockExpr &expr) override;
   void visit (AST::UnsafeBlockExpr &expr) override;
   void visit (AST::ArrayElemsValues &elems) override;