Replace std.ArrayList with bun.collections.ArrayListDefault

Replace 5 instances of `std.ArrayList(...).init(bun.default_allocator)`
with `bun.collections.ArrayListDefault(...)` for better memory management.

Changes:
- src/string.zig: ArrayList(u8) for string formatting
- src/install/lockfile.zig: ArrayList(u8) for lockfile serialization
- src/io/PipeWriter.zig: ArrayList(u8) in StreamBuffer struct
- src/s3/list_objects.zig: ArrayList for S3 contents and prefixes
- src/bundler/bundle_v2.zig: ArrayList(OutputFile) return type

ArrayListDefault uses the default allocator with zero overhead while
providing consistent deinit semantics. Used deinitShallow() where
element types don't have deinit methods (e.g., []const u8).

src/bake/production.zig

@@ -322,7 +322,7 @@ pub fn buildWithVm(ctx: bun.cli.Command.Context, cwd: []const u8, vm: *VirtualMa
         allocator,
         .{ .js = vm.event_loop },
     );
-    const bundled_outputs = bundled_outputs_list.items;
+    const bundled_outputs = bundled_outputs_list.items();
     if (bundled_outputs.len == 0) {
         Output.prettyln("done", .{});
         Output.flush();

src/bundler/bundle_v2.zig

@@ -1548,7 +1548,7 @@ pub const BundleV2 = struct {
         bake_options: BakeOptions,
         alloc: std.mem.Allocator,
         event_loop: EventLoop,
-    ) !std.ArrayList(options.OutputFile) {
+    ) !bun.collections.ArrayListDefault(options.OutputFile) {
         var this = try BundleV2.init(
             server_transpiler,
             bake_options,
@@ -1596,7 +1596,7 @@ pub const BundleV2 = struct {
         );
 
         if (chunks.len == 0) {
-            return std.ArrayList(options.OutputFile).init(bun.default_allocator);
+            return bun.collections.ArrayListDefault(options.OutputFile).init();
         }
 
         return try this.linker.generateChunksInParallel(chunks, false);

src/bundler/linker_context/generateChunksInParallel.zig

@@ -2,7 +2,7 @@ pub fn generateChunksInParallel(
     c: *LinkerContext,
     chunks: []Chunk,
     comptime is_dev_server: bool,
-) !if (is_dev_server) void else std.ArrayList(options.OutputFile) {
+) !if (is_dev_server) void else bun.collections.ArrayListDefault(options.OutputFile) {
     const trace = bun.perf.trace("Bundler.generateChunksInParallel");
     defer trace.end();
 

src/install/lockfile.zig

@@ -1257,7 +1257,7 @@ pub fn saveToDisk(this: *Lockfile, load_result: *const LoadResult, options: *con
             break :bytes writer_buf.list.items;
         }
 
-        var bytes = std.ArrayList(u8).init(bun.default_allocator);
+        var bytes = bun.collections.ArrayListDefault(u8).init();
 
         var total_size: usize = 0;
         var end_pos: usize = 0;
@@ -1265,9 +1265,9 @@ pub fn saveToDisk(this: *Lockfile, load_result: *const LoadResult, options: *con
             Output.err(err, "failed to serialize lockfile", .{});
             Global.crash();
         };
-        if (bytes.items.len >= end_pos)
+        if (bytes.items().len >= end_pos)
-            bytes.items[end_pos..][0..@sizeOf(usize)].* = @bitCast(total_size);
+            bytes.items()[end_pos..][0..@sizeOf(usize)].* = @bitCast(total_size);
-        break :bytes bytes.items;
+        break :bytes bytes.toOwnedSlice() catch bun.outOfMemory();
     };
     defer bun.default_allocator.free(bytes);
 

src/io/PipeWriter.zig

@@ -1097,7 +1097,7 @@ pub fn WindowsBufferedWriter(Parent: type, function_table: anytype) type {
 
 /// Basic std.ArrayList(u8) + usize cursor wrapper
 pub const StreamBuffer = struct {
-    list: std.ArrayList(u8) = std.ArrayList(u8).init(bun.default_allocator),
+    list: bun.collections.ArrayListDefault(u8) = bun.collections.ArrayListDefault(u8).init(),
     cursor: usize = 0,
 
     pub fn reset(this: *StreamBuffer) void {
@@ -1107,19 +1107,19 @@ pub const StreamBuffer = struct {
     }
 
     pub fn maybeShrink(this: *StreamBuffer) void {
-        if (this.list.capacity > std.heap.pageSize()) {
+        if (this.list.capacity() > std.heap.pageSize()) {
             // workaround insane zig decision to make it undefined behavior to resize .len < .capacity
-            this.list.expandToCapacity();
+            this.list.expandToCapacity(undefined);
             this.list.shrinkAndFree(std.heap.pageSize());
         }
     }
 
     pub fn memoryCost(this: *const StreamBuffer) usize {
-        return this.list.capacity;
+        return this.list.capacity();
     }
 
     pub fn size(this: *const StreamBuffer) usize {
-        return this.list.items.len - this.cursor;
+        return this.list.items().len - this.cursor;
     }
 
     pub fn isEmpty(this: *const StreamBuffer) bool {
@@ -1152,7 +1152,7 @@ pub const StreamBuffer = struct {
 
     pub fn writeTypeAsBytesAssumeCapacity(this: *StreamBuffer, comptime T: type, data: T) void {
         var byte_list = bun.ByteList.moveFromList(&this.list);
-        defer this.list = byte_list.moveToListManaged(this.list.allocator);
+        defer this.list = byte_list.moveToListManaged(this.list.allocator());
         byte_list.writeTypeAsBytesAssumeCapacity(T, data);
     }
 
@@ -1164,20 +1164,20 @@ pub const StreamBuffer = struct {
 
             {
                 var byte_list = bun.ByteList.moveFromList(&this.list);
-                defer this.list = byte_list.moveToListManaged(this.list.allocator);
+                defer this.list = byte_list.moveToListManaged(this.list.allocator());
-                _ = try byte_list.writeLatin1(this.list.allocator, buffer);
+                _ = try byte_list.writeLatin1(this.list.allocator(), buffer);
             }
 
-            return this.list.items[this.cursor..];
+            return this.list.items()[this.cursor..];
         } else if (comptime @TypeOf(writeFn) == @TypeOf(&writeUTF16) and writeFn == &writeUTF16) {
             {
                 var byte_list = bun.ByteList.moveFromList(&this.list);
-                defer this.list = byte_list.moveToListManaged(this.list.allocator);
+                defer this.list = byte_list.moveToListManaged(this.list.allocator());
 
-                _ = try byte_list.writeUTF16(this.list.allocator, buffer);
+                _ = try byte_list.writeUTF16(this.list.allocator(), buffer);
             }
 
-            return this.list.items[this.cursor..];
+            return this.list.items()[this.cursor..];
         } else if (comptime @TypeOf(writeFn) == @TypeOf(&write) and writeFn == &write) {
             return buffer;
         } else {
@@ -1193,25 +1193,25 @@ pub const StreamBuffer = struct {
         }
 
         var byte_list = bun.ByteList.moveFromList(&this.list);
-        defer this.list = byte_list.moveToListManaged(this.list.allocator);
+        defer this.list = byte_list.moveToListManaged(this.list.allocator());
 
-        _ = try byte_list.writeLatin1(this.list.allocator, buffer);
+        _ = try byte_list.writeLatin1(this.list.allocator(), buffer);
     }
 
     pub fn writeUTF16(this: *StreamBuffer, buffer: []const u16) OOM!void {
         var byte_list = bun.ByteList.moveFromList(&this.list);
-        defer this.list = byte_list.moveToListManaged(this.list.allocator);
+        defer this.list = byte_list.moveToListManaged(this.list.allocator());
 
-        _ = try byte_list.writeUTF16(this.list.allocator, buffer);
+        _ = try byte_list.writeUTF16(this.list.allocator(), buffer);
     }
 
     pub fn slice(this: *const StreamBuffer) []const u8 {
-        return this.list.items[this.cursor..];
+        return this.list.items()[this.cursor..];
     }
 
     pub fn deinit(this: *StreamBuffer) void {
         this.cursor = 0;
-        if (this.list.capacity > 0) {
+        if (this.list.capacity() > 0) {
             this.list.clearAndFree();
         }
     }

src/s3/list_objects.zig

@@ -59,16 +59,16 @@ pub const S3ListObjectsV2Result = struct {
     continuation_token: ?[]const u8,
     next_continuation_token: ?[]const u8,
     start_after: ?[]const u8,
-    common_prefixes: ?std.ArrayList([]const u8),
+    common_prefixes: ?bun.collections.ArrayListDefault([]const u8),
-    contents: ?std.ArrayList(S3ListObjectsContents),
+    contents: ?bun.collections.ArrayListDefault(S3ListObjectsContents),
 
     pub fn deinit(this: *const @This()) void {
         if (this.contents) |contents| {
-            for (contents.items) |*item| item.deinit();
+            for (contents.items()) |*item| item.deinit();
             contents.deinit();
         }
         if (this.common_prefixes) |common_prefixes| {
-            common_prefixes.deinit();
+            common_prefixes.deinitShallow();
         }
     }
 
@@ -115,9 +115,9 @@ pub const S3ListObjectsV2Result = struct {
         }
 
         if (this.contents) |contents| {
-            const jsContents = try JSValue.createEmptyArray(globalObject, contents.items.len);
+            const jsContents = try JSValue.createEmptyArray(globalObject, contents.items().len);
 
-            for (contents.items, 0..) |item, i| {
+            for (contents.items(), 0..) |item, i| {
                 const objectInfo = JSValue.createEmptyObject(globalObject, 1);
                 objectInfo.put(globalObject, jsc.ZigString.static("key"), try bun.String.createUTF8ForJS(globalObject, item.key));
 
@@ -165,9 +165,9 @@ pub const S3ListObjectsV2Result = struct {
         }
 
         if (this.common_prefixes) |common_prefixes| {
-            const jsCommonPrefixes = try JSValue.createEmptyArray(globalObject, common_prefixes.items.len);
+            const jsCommonPrefixes = try JSValue.createEmptyArray(globalObject, common_prefixes.items().len);
 
-            for (common_prefixes.items, 0..) |prefix, i| {
+            for (common_prefixes.items(), 0..) |prefix, i| {
                 const jsPrefix = JSValue.createEmptyObject(globalObject, 1);
                 jsPrefix.put(globalObject, jsc.ZigString.static("prefix"), try bun.String.createUTF8ForJS(globalObject, prefix));
                 try jsCommonPrefixes.putIndex(globalObject, @intCast(i), jsPrefix);
@@ -196,8 +196,8 @@ pub fn parseS3ListObjectsResult(xml: []const u8) !S3ListObjectsV2Result {
         .start_after = null,
     };
 
-    var contents = std.ArrayList(S3ListObjectsContents).init(bun.default_allocator);
+    var contents = bun.collections.ArrayListDefault(S3ListObjectsContents).init();
-    var common_prefixes = std.ArrayList([]const u8).init(bun.default_allocator);
+    var common_prefixes = bun.collections.ArrayListDefault([]const u8).init();
 
     // we dont use trailing ">" as it may finish with xmlns=...
     if (strings.indexOf(xml, "<ListBucketResult")) |delete_result_pos| {
@@ -482,17 +482,17 @@ pub fn parseS3ListObjectsResult(xml: []const u8) !S3ListObjectsV2Result {
             }
         }
 
-        if (contents.items.len != 0) {
+        if (contents.items().len != 0) {
             result.contents = contents;
         } else {
-            for (contents.items) |*item| item.deinit();
+            for (contents.items()) |*item| item.deinit();
             contents.deinit();
         }
 
-        if (common_prefixes.items.len != 0) {
+        if (common_prefixes.items().len != 0) {
             result.common_prefixes = common_prefixes;
         } else {
-            common_prefixes.deinit();
+            common_prefixes.deinitShallow();
         }
     }
 

src/string.zig

@@ -857,10 +857,10 @@ pub const String = extern struct {
 
     pub fn createFormatForJS(globalObject: *jsc.JSGlobalObject, comptime fmt: [:0]const u8, args: anytype) bun.JSError!jsc.JSValue {
         jsc.markBinding(@src());
-        var builder = std.ArrayList(u8).init(bun.default_allocator);
+        var builder = bun.collections.ArrayListDefault(u8).init();
         defer builder.deinit();
         bun.handleOom(builder.writer().print(fmt, args));
-        return bun.cpp.BunString__createUTF8ForJS(globalObject, builder.items.ptr, builder.items.len);
+        return bun.cpp.BunString__createUTF8ForJS(globalObject, builder.items().ptr, builder.items().len);
     }
 
     pub fn parseDate(this: *String, globalObject: *jsc.JSGlobalObject) bun.JSError!f64 {