From 05fb0d28e18a0da0708eeda3b575fe907ba73f80 Mon Sep 17 00:00:00 2001
From: Rudy Ges <k@klabz.org>
Date: Fri, 17 Nov 2023 17:01:11 +0100
Subject: [PATCH] [hl] don't optimize vars used inside nested try/catch

---
 src/generators/genhl.ml                 | 29 ++++++++++++++++++-------
 tests/unit/src/unit/issues/Issue9174.hx | 18 +++++++++++++++
 2 files changed, 39 insertions(+), 8 deletions(-)
 create mode 100644 tests/unit/src/unit/issues/Issue9174.hx

diff --git a/src/generators/genhl.ml b/src/generators/genhl.ml
index 9b7b21e5665..f3daed21584 100644
--- a/src/generators/genhl.ml
+++ b/src/generators/genhl.ml
@@ -3084,11 +3084,21 @@ and gen_assign_op ctx acc e1 f =
 and build_capture_vars ctx f =
 	let ignored_vars = ref PMap.empty in
 	let used_vars = ref PMap.empty in
+	let depth = ref 0 in
+
 	(* get all captured vars in scope, ignore vars that are declared *)
 	let decl_var v =
-		if has_var_flag v VCaptured then ignored_vars := PMap.add v.v_id () !ignored_vars
+		if has_var_flag v VCaptured then
+		ignored_vars := PMap.add v.v_id !depth !ignored_vars
 	in
 	let use_var v =
+		(* vars used in nested try/catch need to act as captured vars #9174 *)
+		let decl_depth = try PMap.find v.v_id !ignored_vars with Not_found -> !depth in
+		if decl_depth < !depth then begin
+			add_var_flag v VCaptured;
+			ignored_vars := PMap.remove v.v_id !ignored_vars;
+		end;
+
 		if has_var_flag v VCaptured then used_vars := PMap.add v.v_id v !used_vars
 	in
 	let rec loop e =
@@ -3096,15 +3106,18 @@ and build_capture_vars ctx f =
 		| TLocal v ->
 			use_var v;
 		| TVar (v,_) ->
-			decl_var v
-		| TTry (_,catches) ->
-			List.iter (fun (v,_) -> decl_var v) catches
+			decl_var v;
 		| TFunction f ->
 			List.iter (fun (v,_) -> decl_var v) f.tf_args;
-		| _ ->
-			()
-		);
-		Type.iter loop e
+		| _ -> ());
+
+		(match e.eexpr with
+		| TTry (_,catches) ->
+			incr depth;
+			List.iter (fun (v,_) -> decl_var v) catches;
+			Type.iter loop e;
+			decr depth
+		| _ -> Type.iter loop e)
 	in
 	List.iter (fun (v,_) -> decl_var v) f.tf_args;
 	loop f.tf_expr;
diff --git a/tests/unit/src/unit/issues/Issue9174.hx b/tests/unit/src/unit/issues/Issue9174.hx
new file mode 100644
index 00000000000..2d72a0c6c96
--- /dev/null
+++ b/tests/unit/src/unit/issues/Issue9174.hx
@@ -0,0 +1,18 @@
+package unit.issues;
+
+class Issue9174 extends unit.Test {
+	function test() {
+		var result = false;
+		try {
+			try {
+				throw '';
+			} catch(e:String) {
+				result = true;
+				eq(true, result);
+				throw e;
+			}
+		} catch(e:String) {
+			eq(true, result);
+		}
+	}
+}