From 61eb99468429e18bab42e78111c0429befdf7b0e Mon Sep 17 00:00:00 2001
From: dajiaohuang <mikewushuwen@outlook.com>
Date: Sat, 24 Oct 2026 08:44:45 +0800
Subject: [PATCH 1/2] Keep pretty-printer character variable local

---
 lua-parser/pp.lua |  2 +-
 test-pp.lua       | 11 +++++++++++
 test.lua          |  2 ++
 3 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 test-pp.lua

diff --git a/lua-parser/pp.lua b/lua-parser/pp.lua
index 649db38..5eb1ae6 100644
--- a/lua-parser/pp.lua
+++ b/lua-parser/pp.lua
@@ -18,7 +18,7 @@ end
 local function fixed_string (str)
   local new_str = ""
   for i=1,string.len(str) do
-    char = string.byte(str, i)
+    local char = string.byte(str, i)
     if char == 34 then new_str = new_str .. string.format("\\\"")
     elseif char == 92 then new_str = new_str .. string.format("\\\\")
     elseif char == 7 then new_str = new_str .. string.format("\\a")
diff --git a/test-pp.lua b/test-pp.lua
new file mode 100644
index 0000000..505d843
--- /dev/null
+++ b/test-pp.lua
@@ -0,0 +1,11 @@
+local pp = require "lua-parser.pp"
+local saved_char = rawget(_G, "char")
+local sentinel = {}
+_G.char = sentinel
+local ast = {{ tag = "Return", { tag = "String", "hello" } }}
+assert(pp.tostring(ast) == '{ `Return{ `String "hello" } }')
+assert(_G.char == sentinel, "pretty printing changed global char")
+_G.char = nil
+pp.tostring(ast)
+assert(rawget(_G, "char") == nil, "pretty printing created global char")
+_G.char = saved_char
diff --git a/test.lua b/test.lua
index 944215d..978ccb9 100755
--- a/test.lua
+++ b/test.lua
@@ -1,3 +1,5 @@
+dofile("test-pp.lua")
+
 #!/usr/bin/env lua
 
 local parser = require "lua-parser.parser"

From a3b6de36913694beec8ef277a331b2c205e28bbd Mon Sep 17 00:00:00 2001
From: dajiaohuang <mikewushuwen@outlook.com>
Date: Sat, 7 Nov 2026 10:19:23 +0800
Subject: [PATCH 2/2] Run pretty printer checks at end of test suite

---
 test.lua | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/test.lua b/test.lua
index 978ccb9..700a209 100755
--- a/test.lua
+++ b/test.lua
@@ -1,5 +1,3 @@
-dofile("test-pp.lua")
-
 #!/usr/bin/env lua
 
 local parser = require "lua-parser.parser"
@@ -3779,4 +3777,7 @@ assert(r == e)
 r = parse(s)
 assert(r == e)
 
+print("> testing pretty printer...")
+dofile("test-pp.lua")
+
 print("OK")