From 88d3a311e28755e41cec5aba3042e62e8712736c Mon Sep 17 00:00:00 2001
From: Alexey <aleksej.serbinov29@gmail.com>
Date: Thu, 21 May 2026 21:09:58 +0300
Subject: [PATCH] fix(plpgsql): sync generator with committed grammar

Update the PL/pgSQL grammar generator so it matches the committed
plpgsql/grammar.js for drift-sensitive rules.

- emit alias declarations before variable declarations
- emit FETCH as optional FROM plus required cursor name
- add a lightweight generator drift test for decl_statement and stmt_fetch

This prevents future regeneration from undoing the current committed grammar
shape.
---
 script/generate-plpgsql-grammar.js      |  8 +++---
 script/generate-plpgsql-grammar.test.js | 35 +++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 3 deletions(-)
 create mode 100644 script/generate-plpgsql-grammar.test.js

diff --git a/script/generate-plpgsql-grammar.js b/script/generate-plpgsql-grammar.js
index d8808bc..4ab8da3 100644
--- a/script/generate-plpgsql-grammar.js
+++ b/script/generate-plpgsql-grammar.js
@@ -196,6 +196,9 @@ module.exports = grammar({
     ),
 
     decl_statement: $ => choice(
+      // Alias declaration: name ALIAS FOR target ;
+      // Must precede variable declaration so ALIAS is not consumed as a type name.
+      seq($.decl_varname, $.kw_alias, $.kw_for, $.any_identifier, ';'),
       // Variable declaration: name [CONSTANT] type [COLLATE collation] [NOT NULL] [DEFAULT|:=|= expr] ;
       seq(
         $.decl_varname,
@@ -206,8 +209,6 @@ module.exports = grammar({
         optional($.decl_defval),
         ';'
       ),
-      // Alias declaration: name ALIAS FOR target ;
-      seq($.decl_varname, $.kw_alias, $.kw_for, $.any_identifier, ';'),
       // Cursor declaration: name [NO SCROLL | SCROLL] CURSOR [(args)] FOR|IS query ;
       seq(
         $.decl_varname,
@@ -560,7 +561,8 @@ module.exports = grammar({
     stmt_fetch: $ => seq(
       $.kw_fetch,
       optional($.fetch_direction),
-      optional(seq($.kw_from, $.any_identifier)),
+      optional($.kw_from),
+      $.any_identifier,
       $.kw_into,
       $.into_target,
       ';'
diff --git a/script/generate-plpgsql-grammar.test.js b/script/generate-plpgsql-grammar.test.js
new file mode 100644
index 0000000..cbb0db2
--- /dev/null
+++ b/script/generate-plpgsql-grammar.test.js
@@ -0,0 +1,35 @@
+'use strict';
+
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const { test } = require('node:test');
+
+const projectRoot = path.join(__dirname, '..');
+
+function readRepoFile(relativePath) {
+  return fs.readFileSync(path.join(projectRoot, relativePath), 'utf8');
+}
+
+function extractTopLevelRule(source, ruleName) {
+  const pattern = new RegExp(
+    String.raw`^    ${ruleName}: \$ => [\s\S]*?^    \),`,
+    'm'
+  );
+  const match = source.match(pattern);
+  assert.ok(match, `Could not find top-level rule ${ruleName}`);
+  return match[0].trimEnd();
+}
+
+test('PL/pgSQL generator template matches committed grammar for drift-sensitive rules', () => {
+  const generator = readRepoFile('script/generate-plpgsql-grammar.js');
+  const grammar = readRepoFile('plpgsql/grammar.js');
+
+  for (const ruleName of ['decl_statement', 'stmt_fetch']) {
+    assert.equal(
+      extractTopLevelRule(generator, ruleName),
+      extractTopLevelRule(grammar, ruleName),
+      `${ruleName} differs between script/generate-plpgsql-grammar.js and plpgsql/grammar.js`
+    );
+  }
+});