From 531924e7e70c84c1ead2f5b05210dda4f256dd9b Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <m@mitchellh.com>
Date: Thu, 21 Aug 2025 07:27:40 -0700
Subject: [PATCH] terminal: explicitly initialize undefined fields at runtime

This works around the Zig issue as noted in the comment.

No new Valgrind issues found from this.
---
 src/terminal/Parser.zig                 | 34 ++++++++++++++++++-------
 src/terminal/kitty/graphics_command.zig | 24 ++++++++++++-----
 2 files changed, 43 insertions(+), 15 deletions(-)

diff --git a/src/terminal/Parser.zig b/src/terminal/Parser.zig
index ed099ee47..0223545e5 100644
--- a/src/terminal/Parser.zig
+++ b/src/terminal/Parser.zig
@@ -209,26 +209,42 @@ const MAX_INTERMEDIATE = 4;
 const MAX_PARAMS = 24;
 
 /// Current state of the state machine
-state: State = .ground,
+state: State,
 
 /// Intermediate tracking.
-intermediates: [MAX_INTERMEDIATE]u8 = undefined,
-intermediates_idx: u8 = 0,
+intermediates: [MAX_INTERMEDIATE]u8,
+intermediates_idx: u8,
 
 /// Param tracking, building
-params: [MAX_PARAMS]u16 = undefined,
-params_sep: Action.CSI.SepList = .initEmpty(),
-params_idx: u8 = 0,
-param_acc: u16 = 0,
-param_acc_idx: u8 = 0,
+params: [MAX_PARAMS]u16,
+params_sep: Action.CSI.SepList,
+params_idx: u8,
+param_acc: u16,
+param_acc_idx: u8,
 
 /// Parser for OSC sequences
 osc_parser: osc.Parser,
 
 pub fn init() Parser {
-    return .{
+    var result: Parser = .{
+        .state = .ground,
+        .intermediates_idx = 0,
+        .params_sep = .initEmpty(),
+        .params_idx = 0,
+        .param_acc = 0,
+        .param_acc_idx = 0,
         .osc_parser = .init(),
+
+        .intermediates = undefined,
+        .params = undefined,
     };
+    if (std.valgrind.runningOnValgrind() > 0) {
+        // Initialize our undefined fields so Valgrind can catch it.
+        // https://github.com/ziglang/zig/issues/19148
+        result.intermediates = undefined;
+        result.params = undefined;
+    }
+    return result;
 }
 
 pub fn deinit(self: *Parser) void {
diff --git a/src/terminal/kitty/graphics_command.zig b/src/terminal/kitty/graphics_command.zig
index adc6edafe..dcb4850c9 100644
--- a/src/terminal/kitty/graphics_command.zig
+++ b/src/terminal/kitty/graphics_command.zig
@@ -21,14 +21,14 @@ pub const Parser = struct {
     arena: ArenaAllocator,
 
     /// This is the list of KV pairs that we're building up.
-    kv: KV = .{},
+    kv: KV,
 
     /// This is used as a buffer to store the key/value of a KV pair. The value
     /// of a KV pair is at most a 32-bit integer which at most is 10 characters
     /// (4294967295), plus one character for the sign bit on signed ints.
-    kv_temp: [11]u8 = undefined,
-    kv_temp_len: u4 = 0,
-    kv_current: u8 = 0, // Current kv key
+    kv_temp: [11]u8,
+    kv_temp_len: u4,
+    kv_current: u8, // Current kv key
 
     /// This is the list we use to collect the bytes from the data payload.
     /// The Kitty Graphics protocol specification seems to imply that the
@@ -38,7 +38,7 @@ pub const Parser = struct {
     data: std.ArrayList(u8),
 
     /// Internal state for parsing.
-    state: State = .control_key,
+    state: State,
 
     const State = enum {
         /// Parsing k/v pairs. The "ignore" variants are in that state
@@ -57,10 +57,22 @@ pub const Parser = struct {
     pub fn init(alloc: Allocator) Parser {
         var arena = ArenaAllocator.init(alloc);
         errdefer arena.deinit();
-        return .{
+        var result: Parser = .{
             .arena = arena,
             .data = std.ArrayList(u8).init(alloc),
+            .kv = .{},
+            .kv_temp_len = 0,
+            .kv_current = 0,
+            .state = .control_key,
+
+            .kv_temp = undefined,
         };
+        if (std.valgrind.runningOnValgrind() > 0) {
+            // Initialize our undefined fields so Valgrind can catch it.
+            // https://github.com/ziglang/zig/issues/19148
+            result.kv_temp = undefined;
+        }
+        return result;
     }
 
     pub fn deinit(self: *Parser) void {