From 8fd41566167ac74ba2a8eb9fdc1b5139638cc494 Mon Sep 17 00:00:00 2001
From: Chandler Carruth <chandlerc@gmail.com>
Date: Mon, 6 Apr 2026 12:31:54 -0700
Subject: [PATCH] Update tree_sitter for the new `self` syntax and `static var`
 (#7025)

This implements p7016 for tree_sitter. It also updates the build and
source file to allow this to build successfully and documents how to
successfully run these tests with Bazel given that it is fundamentally
not hermetic.

Assisted-by: Antigravity with Gemini
---
 utils/tree_sitter/README.md                   | 21 +++++++++++++++++++
 utils/tree_sitter/grammar.js                  | 10 ++++-----
 .../testdata/string/self_parameter.carbon     | 11 ++++++++++
 .../testdata/string/static_var.carbon         |  7 +++++++
 4 files changed, 43 insertions(+), 6 deletions(-)
 create mode 100644 utils/tree_sitter/testdata/string/self_parameter.carbon
 create mode 100644 utils/tree_sitter/testdata/string/static_var.carbon

diff --git a/utils/tree_sitter/README.md b/utils/tree_sitter/README.md
index b15984e9f262..f37a2422f238 100644
--- a/utils/tree_sitter/README.md
+++ b/utils/tree_sitter/README.md
@@ -17,6 +17,27 @@ To install tree-sitter, run:
 npm install -g tree-sitter-cli
 ```
 
+### Building and Testing
+
+To build and test changes to the grammar using Bazel, provide specific flags to
+allow the build to access the system `tree-sitter` binary and environment.
+
+```bash
+bazel test //utils/tree_sitter:string_tests \
+  --strategy=Genrule=local \
+  --action_env=PATH \
+  --action_env=HOME
+```
+
+-   `--strategy=Genrule=local`: Disables sandboxing for the genrule that runs
+    `tree-sitter generate`, allowing it to find the system-installed binary.
+-   `--action_env=PATH`: Passes your current `PATH` to the build actions,
+    ensuring `tree-sitter` can be found. If `tree-sitter` is not in your default
+    PATH, you can specify it explicitly, for example:
+    `--action_env=PATH=/path/to/tree-sitter/bin:$PATH`.
+-   `--action_env=HOME`: Passes your `HOME` environment variable, which
+    `tree-sitter` may need to locate its configuration or cache.
+
 ## Editor Installation
 
 ### Helix
diff --git a/utils/tree_sitter/grammar.js b/utils/tree_sitter/grammar.js
index da8f2ef7a9a8..155a289ce566 100644
--- a/utils/tree_sitter/grammar.js
+++ b/utils/tree_sitter/grammar.js
@@ -46,6 +46,7 @@ module.exports = grammar({
   conflicts: ($) => [
     [$.paren_pattern, $.paren_expression],
     [$.struct_literal, $.struct_type_literal],
+    [$._pattern_without_expression, $._simple_expression],
   ],
 
   extras: ($) => [/\s/, $.comment],
@@ -163,6 +164,7 @@ module.exports = grammar({
     _pattern_without_expression: ($) =>
       choice(
         'auto',
+        seq(optional('ref'), 'self', optional(seq(':', $._expression))),
         seq($.binding_lhs, ':', $._expression),
         seq($.binding_lhs, ':!', $._expression),
         seq('template', $.binding_lhs, ':!', $._expression),
@@ -316,7 +318,7 @@ module.exports = grammar({
 
     var_declaration: ($) =>
       seq(
-        'var',
+        seq(optional('static'), 'var'),
         $._pattern_without_expression,
         optional(seq('=', $._expression)),
         ';'
@@ -379,11 +381,7 @@ module.exports = grammar({
     generic_binding: ($) =>
       seq(optional('template'), $.ident, ':!', $._expression),
 
-    deduced_param: ($) =>
-      choice(
-        $.generic_binding,
-        seq(optional('addr'), 'self', ':', $._expression)
-      ),
+    deduced_param: ($) => $.generic_binding,
 
     deduced_params: ($) => seq('[', comma_sep($.deduced_param), ']'),
 
diff --git a/utils/tree_sitter/testdata/string/self_parameter.carbon b/utils/tree_sitter/testdata/string/self_parameter.carbon
new file mode 100644
index 000000000000..19a44548e652
--- /dev/null
+++ b/utils/tree_sitter/testdata/string/self_parameter.carbon
@@ -0,0 +1,11 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+class Point {
+  var x: i32;
+
+  fn GetX(self: Point) -> i32 { return self.x; }
+  fn GetY(self) -> i32 { return 0; }
+  fn SetX(ref self, new_x: i32) {}
+}
diff --git a/utils/tree_sitter/testdata/string/static_var.carbon b/utils/tree_sitter/testdata/string/static_var.carbon
new file mode 100644
index 000000000000..f523a7ddda54
--- /dev/null
+++ b/utils/tree_sitter/testdata/string/static_var.carbon
@@ -0,0 +1,7 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+class Widget {
+  static var count: i32;
+}