From 2787c40ebefbecf92e8e57ff404db26b0f1a1e6d Mon Sep 17 00:00:00 2001
From: Zef Hemel <zef@zef.me>
Date: Fri, 28 Mar 2025 12:50:35 +0100
Subject: [PATCH] Better Lua parse error reporting

---
 plug-api/lib/tree.test.ts |  6 ------
 plug-api/lib/tree.ts      | 25 +------------------------
 plugs/index/lint.ts       | 14 +++++++-------
 3 files changed, 8 insertions(+), 37 deletions(-)

diff --git a/plug-api/lib/tree.test.ts b/plug-api/lib/tree.test.ts
index f5b967e4..32949c92 100644
--- a/plug-api/lib/tree.test.ts
+++ b/plug-api/lib/tree.test.ts
@@ -4,7 +4,6 @@ import {
   collectNodesMatching,
   findParentMatching,
   nodeAtPos,
-  parseTreeToAST,
   removeParentPointers,
   renderToText,
   replaceNodesMatching,
@@ -69,8 +68,3 @@ Deno.test("Test parsing", () => {
   parse(extendedMarkdownLanguage, mdTest3);
   // console.log(JSON.stringify(mdTree3, null, 2));
 });
-
-Deno.test("AST functions", () => {
-  const mdTree = parse(extendedMarkdownLanguage, mdTest1);
-  console.log(JSON.stringify(parseTreeToAST(mdTree), null, 2));
-});
diff --git a/plug-api/lib/tree.ts b/plug-api/lib/tree.ts
index c4b65ce3..a731face 100644
--- a/plug-api/lib/tree.ts
+++ b/plug-api/lib/tree.ts
@@ -214,33 +214,10 @@ export function cloneTree(tree: ParseTree): ParseTree {
   return newTree;
 }
 
-export function parseTreeToAST(tree: ParseTree, omitTrimmable = true): AST {
-  if (tree.type === "⚠") {
-    // console.info("Parse error", JSON.stringify(tree, null, 2));
-    throw new Error(
-      `Parse error in: ${renderToText(tree)}`,
-    );
-  }
-  if (tree.text !== undefined) {
-    return tree.text;
-  }
-  const ast: AST = [tree.type!];
-  for (const node of tree.children!) {
-    if (node.type && !node.type.endsWith("Mark") && node.type !== "Comment") {
-      ast.push(parseTreeToAST(node, omitTrimmable));
-    }
-    if (node.text && (omitTrimmable && node.text.trim() || !omitTrimmable)) {
-      ast.push(node.text);
-    }
-  }
-  return ast;
-}
-
 export function cleanTree(tree: ParseTree, omitTrimmable = true): ParseTree {
   if (tree.type === "⚠") {
-    // console.info("Parse error", JSON.stringify(tree, null, 2));
     throw new Error(
-      `Parse error in: ${renderToText(tree)}`,
+      `Parse error at pos ${tree.from}`,
     );
   }
   if (tree.text !== undefined) {
diff --git a/plugs/index/lint.ts b/plugs/index/lint.ts
index ef3c4c95..57ed01a3 100644
--- a/plugs/index/lint.ts
+++ b/plugs/index/lint.ts
@@ -103,18 +103,18 @@ export async function lintLua({ tree }: LintEvent): Promise<LintDiagnostic[]> {
         const offset = codeText.from!;
         let from = codeText.from!;
         let to = codeText.to!;
-        if (e.message.includes("Parse error (")) {
-          const errorMatch = errorRegex.exec(e.message);
-          if (errorMatch) {
-            from = offset + parseInt(errorMatch[1], 10);
-            to = offset + parseInt(errorMatch[2], 10);
-          }
+        let message = e.message;
+        if (message.includes("Parse error")) {
+          const pos = +message.slice("Parse error at pos ".length);
+          from = offset + pos;
+          to = offset + pos;
+          message = "Parse error";
         }
         diagnostics.push({
           from,
           to,
           severity: "error",
-          message: e.message,
+          message,
         });
         console.log("Lua error", e);
       }