From c1c4532cc52458081e3570149d380d0dd19679cd Mon Sep 17 00:00:00 2001
From: Wunka <56411012+Wunka@users.noreply.github.com>
Date: Sun, 30 Aug 2026 17:26:02 +0200
Subject: [PATCH] add mark_comment rule

---
 src/rules/_list.zig        |  3 ++-
 src/rules/mark_comment.zig | 39 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 src/rules/mark_comment.zig

diff --git a/src/rules/_list.zig b/src/rules/_list.zig
index 5716652..3dc18af 100644
--- a/src/rules/_list.zig
+++ b/src/rules/_list.zig
@@ -4,7 +4,8 @@ pub const comment_start = @import("comment_start.zig");
 pub const empty_line_at_file_end = @import("empty_line_at_file_end.zig");
 pub const if_for_while_braces = @import("if_for_while_braces.zig");
 pub const imports = @import("imports.zig");
+pub const mark_comment = @import("mark_comment.zig");
+pub const orelse_unreachable = @import("orelse_unreachable.zig");
 pub const tab_indentation = @import("tab_indentation.zig");
 pub const trailing_space = @import("trailing_space.zig");
-pub const orelse_unreachable = @import("orelse_unreachable.zig");
 pub const unused_private_decls = @import("unused_private_decls.zig");
diff --git a/src/rules/mark_comment.zig b/src/rules/mark_comment.zig
new file mode 100644
index 0000000..f3492f0
--- /dev/null
+++ b/src/rules/mark_comment.zig
@@ -0,0 +1,39 @@
+const std = @import("std");
+
+const main = @import("main");
+
+const maxLineNumber = 100;
+
+pub fn check(ctx: main.Context) void {
+	const ast = ctx.ast orelse return;
+
+	var buffer: [2]std.zig.Ast.Node.Index = undefined;
+	for (0..ast.nodes.len) |nodeIndex| {
+		const node: std.zig.Ast.Node.Index = @enumFromInt(nodeIndex);
+		if (ast.nodeTag(node) != .simple_var_decl) continue;
+		const varDec = ast.simpleVarDecl(node);
+		if (varDec.ast.type_node.unwrap() != null) continue;
+		var name = ast.tokenSlice(varDec.ast.mut_token + 1);
+		if (name.len != 0 and name[0] == '@') name = name[2 .. name.len - 1];
+
+		const rhsNode = varDec.ast.init_node.unwrap() orelse continue;
+		_ = ast.fullContainerDecl(&buffer, rhsNode) orelse continue;
+
+		const firstToken = ast.firstToken(rhsNode);
+		const lastToken = ast.lastToken(rhsNode);
+
+		const firstTokenlocation = ast.tokenLocation(firstToken, firstToken);
+		const lastTokenlocation = ast.tokenLocation(firstToken, lastToken);
+
+		if (lastTokenlocation.line - firstTokenlocation.line < maxLineNumber) continue;
+
+		const lineText = ctx.data[firstTokenlocation.line_start..firstTokenlocation.line_end];
+		const markComment = std.fmt.allocPrint(main.allocator, "// MARK: {s}", .{name}) catch @panic("OOM");
+		defer main.allocator.free(markComment);
+		if (std.mem.endsWith(u8, lineText, markComment)) continue;
+
+		const msg = std.fmt.allocPrint(main.allocator, "Container over the size of {d} should have a MARK comment like this: \"// MARK: {s}\"", .{maxLineNumber, name}) catch @panic("OOM");
+		defer main.allocator.free(msg);
+		ctx.printError(msg, firstTokenlocation.line_end);
+	}
+}