From e7ed073be31c03879ed4bd33d07510033d4ebbd2 Mon Sep 17 00:00:00 2001
From: Turiiya <34311583+ttytm@users.noreply.github.com>
Date: Mon, 25 Mar 2024 12:09:52 +0100
Subject: [PATCH] parser, fmt: parse methods on JS interfaces, write JS method
 bodies (#21088)

---
 vlib/v/fmt/fmt.v                                     |  2 +-
 vlib/v/fmt/tests/interface_js_interop_method_keep.vv | 11 +++++++++++
 vlib/v/parser/fn.v                                   |  2 +-
 vlib/v/parser/tests/interop_js_func_body_err.out     |  3 +++
 vlib/v/parser/tests/interop_js_func_body_err.vv      |  1 +
 5 files changed, 17 insertions(+), 2 deletions(-)
 create mode 100644 vlib/v/fmt/tests/interface_js_interop_method_keep.vv
 create mode 100644 vlib/v/parser/tests/interop_js_func_body_err.out
 create mode 100644 vlib/v/parser/tests/interop_js_func_body_err.vv

diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index e4167a07d..93713ebcb 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -1104,7 +1104,7 @@ fn (mut f Fmt) fn_body(node ast.FnDecl) {
 	defer {
 		f.fn_scope = prev_fn_scope
 	}
-	if node.language == .v {
+	if node.language == .v || (node.is_method && node.language == .js) {
 		if !node.no_body {
 			f.write(' {')
 			pre_comments := node.comments.filter(it.pos.pos < node.name_pos.pos)
diff --git a/vlib/v/fmt/tests/interface_js_interop_method_keep.vv b/vlib/v/fmt/tests/interface_js_interop_method_keep.vv
new file mode 100644
index 000000000..0cb900dba
--- /dev/null
+++ b/vlib/v/fmt/tests/interface_js_interop_method_keep.vv
@@ -0,0 +1,11 @@
+pub interface JS.CanvasRenderingContext2D {
+	setLineDash(JS.Array)
+}
+
+pub fn (ctx JS.CanvasRenderingContext2D) set_line_dash(arr []f64) {
+	tmp := JS.Array.prototype.constructor()
+	for x in arr {
+		tmp.push(JS.Number(x))
+	}
+	ctx.setLineDash(tmp)
+}
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index 84abac495..680383b70 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -577,7 +577,7 @@ run them via `v file.v` instead',
 	mut stmts := []ast.Stmt{}
 	body_start_pos := p.tok.pos()
 	if p.tok.kind == .lcbr {
-		if language != .v {
+		if language != .v && !(language == .js && type_sym.info is ast.Interface) {
 			p.error_with_pos('interop functions cannot have a body', body_start_pos)
 		}
 		p.inside_fn = true
diff --git a/vlib/v/parser/tests/interop_js_func_body_err.out b/vlib/v/parser/tests/interop_js_func_body_err.out
new file mode 100644
index 000000000..9c871b7ed
--- /dev/null
+++ b/vlib/v/parser/tests/interop_js_func_body_err.out
@@ -0,0 +1,3 @@
+vlib/v/parser/tests/interop_js_func_body_err.vv:1:43: error: interop functions cannot have a body
+    1 | fn JS.state_is_ready_on_leave(retval int) {}
+      |                                           ^
diff --git a/vlib/v/parser/tests/interop_js_func_body_err.vv b/vlib/v/parser/tests/interop_js_func_body_err.vv
new file mode 100644
index 000000000..205c9a5f3
--- /dev/null
+++ b/vlib/v/parser/tests/interop_js_func_body_err.vv
@@ -0,0 +1 @@
+fn JS.state_is_ready_on_leave(retval int) {}
-- 
2.39.5