Merge #1218

1218: Lower IfLet expressions r=CohenArthur a=antego

This PR addresses https://github.com/Rust-GCC/gccrs/issues/1177. This change implements the "hir-lowering" part of the plan outlined here https://github.com/Rust-GCC/gccrs/issues/1177#issuecomment-1118530135.

Co-authored-by: antego <antego@users.noreply.github.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/gcc/rust/hir/rust-ast-lower-block.h b/gcc/rust/hir/rust-ast-lower-block.h
index 512f4709..5c328b5 100644
--- a/gcc/rust/hir/rust-ast-lower-block.h
+++ b/gcc/rust/hir/rust-ast-lower-block.h
@@ -120,6 +120,35 @@ private:
   bool terminated;
 };
 
+class ASTLoweringIfLetBlock : public ASTLoweringBase
+{
+  using Rust::HIR::ASTLoweringBase::visit;
+
+public:
+  static HIR::IfLetExpr *translate (AST::IfLetExpr *expr)
+  {
+    ASTLoweringIfLetBlock resolver;
+    expr->accept_vis (resolver);
+    if (resolver.translated != nullptr)
+      {
+	resolver.mappings->insert_hir_expr (
+	  resolver.translated->get_mappings ().get_crate_num (),
+	  resolver.translated->get_mappings ().get_hirid (),
+	  resolver.translated);
+      }
+    return resolver.translated;
+  }
+
+  ~ASTLoweringIfLetBlock () {}
+
+  void visit (AST::IfLetExpr &expr) override;
+
+private:
+  ASTLoweringIfLetBlock () : ASTLoweringBase (), translated (nullptr) {}
+
+  HIR::IfLetExpr *translated;
+};
+
 class ASTLoweringExprWithBlock : public ASTLoweringBase
 {
   using Rust::HIR::ASTLoweringBase::visit;
@@ -159,6 +188,11 @@ public:
     translated = ASTLoweringIfBlock::translate (&expr, &terminated);
   }
 
+  void visit (AST::IfLetExpr &expr) override
+  {
+    translated = ASTLoweringIfLetBlock::translate (&expr);
+  }
+
   void visit (AST::BlockExpr &expr) override
   {
     translated = ASTLoweringBlock::translate (&expr, &terminated);