fix: Zig 0.16.0 compatibility

build.zig.zon

@@ -2,7 +2,7 @@
     .name = .gremlin,
     .version = "0.1.0",
     .fingerprint = 0x52f178c9d53d6b13,
-    .minimum_zig_version = "0.15.2",
+    .minimum_zig_version = "0.16.0",
 
     .paths = .{""},
 }

integration-test/benchmark.zig

@@ -128,48 +128,48 @@ fn updateGoldenMessage(msg: *unittest.TestAllTypes, repeated_storage: []?unittes
 fn createDeepNested() benchmark.DeepNested {
     const items_level1 = [_]?benchmark.Level1{
         benchmark.Level1{
-        .id = 11,
-        .title = "item1_top_level",
-        .score = 2.34,
-        .nested = benchmark.Level2{
-            .id = 110,
-            .description = "nested_in_top_item1",
-            .payload = "some payload data",
-            .nested = benchmark.Level3{
-                .id = 1100,
-                .name = "deeply_nested_top_item1",
+            .id = 11,
+            .title = "item1_top_level",
+            .score = 2.34,
+            .nested = benchmark.Level2{
+                .id = 110,
+                .description = "nested_in_top_item1",
+                .payload = "some payload data",
+                .nested = benchmark.Level3{
+                    .id = 1100,
+                    .name = "deeply_nested_top_item1",
+                },
             },
         },
-        },
         benchmark.Level1{
-        .id = 12,
-        .title = "item2_top_level",
-        .score = 3.45,
-        .nested = benchmark.Level2{
-            .id = 120,
-            .description = "nested_in_top_item2",
-            .payload = "more payload data here",
-        },
+            .id = 12,
+            .title = "item2_top_level",
+            .score = 3.45,
+            .nested = benchmark.Level2{
+                .id = 120,
+                .description = "nested_in_top_item2",
+                .payload = "more payload data here",
+            },
         },
         benchmark.Level1{
-        .id = 13,
-        .title = "item3_top_level",
-        .score = 4.56,
+            .id = 13,
+            .title = "item3_top_level",
+            .score = 4.56,
         },
         benchmark.Level1{
-        .id = 14,
-        .title = "item4_top_level",
-        .score = 5.67,
-        .nested = benchmark.Level2{
-            .id = 140,
-            .description = "nested_in_top_item4",
-            .payload = "final payload data",
-        },
+            .id = 14,
+            .title = "item4_top_level",
+            .score = 5.67,
+            .nested = benchmark.Level2{
+                .id = 140,
+                .description = "nested_in_top_item4",
+                .payload = "final payload data",
+            },
         },
         benchmark.Level1{
-        .id = 15,
-        .title = "item5_top_level",
-        .score = 6.78,
+            .id = 15,
+            .title = "item5_top_level",
+            .score = 6.78,
         },
     };
 
@@ -193,23 +193,23 @@ fn createDeepNested() benchmark.DeepNested {
 
     const items_level3 = [_]?benchmark.Level3{
         benchmark.Level3{
-        .id = 31,
-        .name = "item1_nested",
-        .nested = benchmark.Level4{
-            .value = 310,
-            .data = "nested_item1_data",
-            .numbers = &[_]i32{ 1, 2, 3, 4, 5 },
-        },
+            .id = 31,
+            .name = "item1_nested",
+            .nested = benchmark.Level4{
+                .value = 310,
+                .data = "nested_item1_data",
+                .numbers = &[_]i32{ 1, 2, 3, 4, 5 },
+            },
             .items = &sub_items1,
         },
         benchmark.Level3{
-        .id = 32,
-        .name = "item2_nested",
-        .nested = benchmark.Level4{
-            .value = 320,
-            .data = "nested_item2_data",
-            .numbers = &[_]i32{ 6, 7, 8, 9, 10 },
-        },
+            .id = 32,
+            .name = "item2_nested",
+            .nested = benchmark.Level4{
+                .value = 320,
+                .data = "nested_item2_data",
+                .numbers = &[_]i32{ 6, 7, 8, 9, 10 },
+            },
             .items = &sub_items2,
         },
         benchmark.Level3{
@@ -234,32 +234,32 @@ fn createDeepNested() benchmark.DeepNested {
 
     const items_level2 = [_]?benchmark.Level2{
         benchmark.Level2{
-        .id = 21,
-        .description = "item1_level2_with_payload",
-        .payload = "payload for item 1",
-        .nested = benchmark.Level3{
-            .id = 210,
-            .name = "nested_in_item1",
-            .nested = benchmark.Level4{
-                .value = 2100,
-                .data = "deep_nested",
-                .numbers = &[_]i32{ 100, 200, 300 },
+            .id = 21,
+            .description = "item1_level2_with_payload",
+            .payload = "payload for item 1",
+            .nested = benchmark.Level3{
+                .id = 210,
+                .name = "nested_in_item1",
+                .nested = benchmark.Level4{
+                    .value = 2100,
+                    .data = "deep_nested",
+                    .numbers = &[_]i32{ 100, 200, 300 },
+                },
             },
         },
-        },
         benchmark.Level2{
-        .id = 22,
-        .description = "item2_level2_with_payload",
-        .payload = "payload for item 2 with more data",
-        .nested = benchmark.Level3{
-            .id = 220,
-            .name = "nested_in_item2",
-        },
+            .id = 22,
+            .description = "item2_level2_with_payload",
+            .payload = "payload for item 2 with more data",
+            .nested = benchmark.Level3{
+                .id = 220,
+                .name = "nested_in_item2",
+            },
         },
         benchmark.Level2{
-        .id = 23,
-        .description = "item3_level2_with_payload",
-        .payload = "payload for item 3",
+            .id = 23,
+            .description = "item3_level2_with_payload",
+            .payload = "payload for item 3",
         },
         benchmark.Level2{
             .id = 24,

src/codegen/gen.zig

@@ -63,7 +63,7 @@ fn createFile(
     const rel_to_proto = if (well_known_types.isWellKnownImport(file_path))
         try allocator.dupe(u8, file_path)
     else
-        try std.fs.path.relativePosix(allocator, proto_root, file_path);
+        try std.fs.path.relativePosix(allocator, "/", proto_root, file_path);
     defer allocator.free(rel_to_proto);
 
     // Generate output path
@@ -99,11 +99,12 @@ fn createFile(
 ///        OutOfMemory if allocation fails
 pub fn generateProtobuf(
     allocator: std.mem.Allocator,
+    io: std.Io,
     proto_root: []const u8,
     target_root: []const u8,
     ignore_masks: ?[]const []const u8,
 ) !void {
-    var parsed = try gremlin_parser.parse(allocator, proto_root, ignore_masks);
+    var parsed = try gremlin_parser.parse(allocator, io, proto_root, ignore_masks);
     defer parsed.deinit();
 
     // Create ZigFile instances
@@ -129,7 +130,7 @@ pub fn generateProtobuf(
     try resolveReferences(&files);
 
     // Generate code for each file
-    try generateCode(allocator, &files);
+    try generateCode(allocator, io, &files);
 }
 
 /// Resolves cross-file references between all generated files.
@@ -153,10 +154,10 @@ fn resolveReferences(files: *std.ArrayList(ZigFile)) !void {
 /// Parameters:
 ///   - allocator: Memory allocator for file operations
 ///   - files: List of ZigFile instances to generate code for
-fn generateCode(allocator: std.mem.Allocator, files: *std.ArrayList(ZigFile)) !void {
+fn generateCode(allocator: std.mem.Allocator, io: std.Io, files: *std.ArrayList(ZigFile)) !void {
     for (files.items) |*file| {
         var out_file = try FileOutput.init(allocator, file.out_path);
         try file.write(&out_file);
-        try out_file.close();
+        try out_file.close(io);
     }
 }

src/codegen/gen/enum.zig

@@ -114,9 +114,9 @@ pub const ZigEnum = struct {
     ///
     /// Returns: A newly allocated string containing the Zig enum code
     pub fn createEnumDef(self: *const ZigEnum, allocator: std.mem.Allocator) ![]const u8 {
-        var buffer = try std.ArrayList(u8).initCapacity(allocator, 1024);
-        errdefer buffer.deinit(allocator);
-        var writer = buffer.writer(allocator);
+        var aw = try std.Io.Writer.Allocating.initCapacity(allocator, 1024);
+        errdefer aw.deinit();
+        const writer = &aw.writer;
 
         try writer.print("pub const {s} = enum(i32) {{\n", .{self.const_name});
 
@@ -126,7 +126,7 @@ pub const ZigEnum = struct {
         }
 
         try writer.writeAll("};\n");
-        return buffer.toOwnedSlice(allocator);
+        return aw.toOwnedSlice();
     }
 
     /// Frees all resources associated with this enum definition.

src/codegen/gen/fields/bytes.zig

@@ -59,7 +59,11 @@ fn formatStringLiteral(allocator: std.mem.Allocator, str: []const u8) ![]const u
             '"' => try result.appendSlice(allocator, "\\\""),
 
             // All other characters are converted to hex for consistent representation
-            else => try std.fmt.format(result.writer(allocator), "\\x{X:0>2}", .{c}),
+            else => {
+                const hex = try std.fmt.allocPrint(allocator, "\\x{X:0>2}", .{c});
+                defer allocator.free(hex);
+                try result.appendSlice(allocator, hex);
+            },
         }
     }
     try result.appendSlice(allocator, "\"");

src/codegen/gen/import.zig

@@ -132,7 +132,7 @@ pub fn importResolve(
     const imported_file_rel_path_from_proto_root = if (well_known_types.isWellKnownImport(import_path_in_proto_file))
         try allocator.dupe(u8, import_path_in_proto_file)
     else
-        try std.fs.path.relativePosix(allocator, proto_root, import_path_in_proto_file);
+        try std.fs.path.relativePosix(allocator, "/", proto_root, import_path_in_proto_file);
     defer allocator.free(imported_file_rel_path_from_proto_root);
 
     // Generate output path for the imported file
@@ -154,7 +154,7 @@ pub fn importResolve(
     } else {
         // Different directory - compute path relative to the importing file's output location
         // First, get the output path for the current file (the one doing the importing)
-        const current_file_rel_to_proto_root = try std.fs.path.relativePosix(allocator, proto_root, proto_file_path);
+        const current_file_rel_to_proto_root = try std.fs.path.relativePosix(allocator, "/", proto_root, proto_file_path);
         defer allocator.free(current_file_rel_to_proto_root);
 
         const current_file_out_path = try paths.outputPath(allocator, current_file_rel_to_proto_root, target_root);
@@ -164,7 +164,7 @@ pub fn importResolve(
         const current_out_dir = std.fs.path.dirname(current_file_out_path) orelse ".";
 
         // Compute relative path from current file's directory to imported file
-        const rel_import_path = try std.fs.path.relativePosix(allocator, current_out_dir, out_path);
+        const rel_import_path = try std.fs.path.relativePosix(allocator, "/", current_out_dir, out_path);
         defer allocator.free(rel_import_path);
 
         return try ZigImport.init(allocator, src, name, rel_import_path);

src/codegen/gen/output.zig

@@ -91,17 +91,16 @@ pub const FileOutput = struct {
     /// Collapses consecutive newlines into single newlines.
     ///
     /// Returns: Error if file operations fail
-    pub fn close(self: *FileOutput) !void {
+    pub fn close(self: *FileOutput, io: std.Io) !void {
         // Ensure directory exists
         const dir_path = std.fs.path.dirname(self.path) orelse return error.InvalidPath;
-        try std.fs.cwd().makePath(dir_path);
+        try std.Io.Dir.cwd().createDirPath(io, dir_path);
 
         // Create or truncate output file
-        const file = try std.fs.cwd().createFile(self.path, .{
+        var file = try std.Io.Dir.cwd().createFile(io, self.path, .{
             .truncate = true,
-            .read = false,
         });
-        defer file.close();
+        defer file.close(io);
 
         // Collapse consecutive newlines into single newlines
         var processed = try std.ArrayList(u8).initCapacity(self.allocator, self.content.items.len);
@@ -130,11 +129,11 @@ pub const FileOutput = struct {
 
         // Write content up to the last non-newline character
         if (trimmed_len > 0) {
-            try file.writeAll(processed.items[0..trimmed_len]);
+            try file.writeStreamingAll(io, processed.items[0..trimmed_len]);
         }
 
         // Always add exactly one newline at the end
-        try file.writeAll("\n");
+        try file.writeStreamingAll(io, "\n");
 
         // Free the content buffer
         self.content.deinit(self.allocator);

src/gremlin/types.zig

@@ -57,8 +57,9 @@ pub const SizedBool = Sized(bool);
 pub const SizedBytes = Sized([]const u8);
 
 /// Protocol buffer encoding/decoding errors
-pub const Error = error{ InvalidVarInt, // Invalid variable integer encoding
+pub const Error = error{
+    InvalidVarInt, // Invalid variable integer encoding
     InvalidTag, // Invalid field tag
     InvalidData, // Data doesn't match expected format
-    OutOfMemory // Memory allocation failed
-    };
+    OutOfMemory, // Memory allocation failed
+};

src/parser/entries/buffer.zig

@@ -36,11 +36,8 @@ pub const ParserBuffer = struct {
 
     /// Initialize a ParserBuffer by reading the entire contents of a file
     /// Caller owns the memory and must call deinit()
-    pub fn initFile(allocator: std.mem.Allocator, path: []const u8) !ParserBuffer {
-        var file = try std.fs.openFileAbsolute(path, .{ .mode = .read_only });
-        defer file.close();
-
-        const buf = try file.readToEndAlloc(allocator, std.math.maxInt(usize));
+    pub fn initFile(allocator: std.mem.Allocator, io: std.Io, path: []const u8) !ParserBuffer {
+        const buf = try std.Io.Dir.cwd().readFileAlloc(io, path, allocator, .unlimited);
         return ParserBuffer{ .buf = buf, .allocator = allocator };
     }
 
@@ -253,10 +250,11 @@ test "large comment" {
 }
 
 test "file read" {
-    var path_buffer: [std.fs.max_path_bytes]u8 = undefined;
-    const path = try std.fs.realpath("test_data/google/proto3.proto", &path_buffer);
+    var path_buffer: [std.Io.Dir.max_path_bytes]u8 = undefined;
+    const n = try std.Io.Dir.cwd().realPathFile(std.testing.io, "test_data/google/proto3.proto", &path_buffer);
+    const path = path_buffer[0..n];
 
-    var buf = try ParserBuffer.initFile(std.testing.allocator, path);
+    var buf = try ParserBuffer.initFile(std.testing.allocator, std.testing.io, path);
     try std.testing.expect(buf.buf.len > 0);
     buf.deinit();
 }

src/parser/entries/service.zig

@@ -85,7 +85,7 @@ test "service parsing" {
 
     // Test case 3: Service with nested braces
     {
-        var buf = ParserBuffer{ .buf = 
+        var buf = ParserBuffer{ .buf =
             \\service Test {
             \\    rpc Method1 (Request) { option deprecated = true; }
             \\    rpc Method2 (Request) returns (Response) { option idempotency_level = "NO_SIDE_EFFECTS"; }