Move ArrayListSentineled to std lib orphanage

lib/std/array_list.zig

@@ -91,6 +91,13 @@ pub fn ArrayListAligned(comptime T: type, comptime alignment: ?u29) type {
             return result;
         }
 
+        /// The caller owns the returned memory. ArrayList becomes empty.
+        pub fn toOwnedSliceSentinel(self: *Self, comptime sentinel: T) ![:sentinel]T {
+            try self.append(sentinel);
+            const result = self.toOwnedSlice();
+            return result[0 .. result.len - 1 :sentinel];
+        }
+
         /// Insert `item` at index `n` by moving `list[n .. list.len]` to make room.
         /// This operation is O(N).
         pub fn insert(self: *Self, n: usize, item: T) !void {
@@ -389,6 +396,13 @@ pub fn ArrayListAlignedUnmanaged(comptime T: type, comptime alignment: ?u29) typ
             return result;
         }
 
+        /// The caller owns the returned memory. ArrayList becomes empty.
+        pub fn toOwnedSliceSentinel(self: *Self, allocator: *Allocator, comptime sentinel: T) ![:sentinel]T {
+            try self.append(allocator, sentinel);
+            const result = self.toOwnedSlice(allocator);
+            return result[0 .. result.len - 1 :sentinel];
+        }
+
         /// Insert `item` at index `n`. Moves `list[n .. list.len]`
         /// to make room.
         pub fn insert(self: *Self, allocator: *Allocator, n: usize, item: T) !void {
@@ -1121,3 +1135,27 @@ test "std.ArrayList/ArrayListUnmanaged.addManyAsArray" {
         testing.expectEqualSlices(u8, list.items, "aoeuasdf");
     }
 }
+
+test "std.ArrayList/ArrayListUnmanaged.toOwnedSliceSentinel" {
+    const a = testing.allocator;
+    {
+        var list = ArrayList(u8).init(a);
+        defer list.deinit();
+
+        try list.appendSlice("foobar");
+
+        const result = try list.toOwnedSliceSentinel(0);
+        defer a.free(result);
+        testing.expectEqualStrings(result, mem.spanZ(result.ptr));
+    }
+    {
+        var list = ArrayListUnmanaged(u8){};
+        defer list.deinit(a);
+
+        try list.appendSlice(a, "foobar");
+
+        const result = try list.toOwnedSliceSentinel(a, 0);
+        defer a.free(result);
+        testing.expectEqualStrings(result, mem.spanZ(result.ptr));
+    }
+}

lib/std/child_process.zig

@@ -15,7 +15,6 @@ const windows = os.windows;
 const mem = std.mem;
 const debug = std.debug;
 const BufMap = std.BufMap;
-const ArrayListSentineled = std.ArrayListSentineled;
 const builtin = @import("builtin");
 const Os = builtin.Os;
 const TailQueue = std.TailQueue;
@@ -749,38 +748,37 @@ fn windowsCreateProcess(app_name: [*:0]u16, cmd_line: [*:0]u16, envp_ptr: ?[*]u1
 
 /// Caller must dealloc.
 fn windowsCreateCommandLine(allocator: *mem.Allocator, argv: []const []const u8) ![:0]u8 {
-    var buf = try ArrayListSentineled(u8, 0).initSize(allocator, 0);
+    var buf = std.ArrayList(u8).init(allocator);
     defer buf.deinit();
-    const buf_stream = buf.outStream();
 
     for (argv) |arg, arg_i| {
-        if (arg_i != 0) try buf_stream.writeByte(' ');
+        if (arg_i != 0) try buf.append(' ');
         if (mem.indexOfAny(u8, arg, " \t\n\"") == null) {
-            try buf_stream.writeAll(arg);
+            try buf.appendSlice(arg);
             continue;
         }
-        try buf_stream.writeByte('"');
+        try buf.append('"');
         var backslash_count: usize = 0;
         for (arg) |byte| {
             switch (byte) {
                 '\\' => backslash_count += 1,
                 '"' => {
-                    try buf_stream.writeByteNTimes('\\', backslash_count * 2 + 1);
-                    try buf_stream.writeByte('"');
+                    try buf.appendNTimes('\\', backslash_count * 2 + 1);
+                    try buf.append('"');
                     backslash_count = 0;
                 },
                 else => {
-                    try buf_stream.writeByteNTimes('\\', backslash_count);
-                    try buf_stream.writeByte(byte);
+                    try buf.appendNTimes('\\', backslash_count);
+                    try buf.append(byte);
                     backslash_count = 0;
                 },
             }
         }
-        try buf_stream.writeByteNTimes('\\', backslash_count * 2);
-        try buf_stream.writeByte('"');
+        try buf.appendNTimes('\\', backslash_count * 2);
+        try buf.append('"');
     }
 
-    return buf.toOwnedSlice();
+    return buf.toOwnedSliceSentinel(0);
 }
 
 fn windowsDestroyPipe(rd: ?windows.HANDLE, wr: ?windows.HANDLE) void {

lib/std/io.zig

@@ -209,6 +209,7 @@ test "" {
     _ = @import("io/buffered_writer.zig");
     _ = @import("io/c_writer.zig");
     _ = @import("io/counting_writer.zig");
+    _ = @import("io/counting_reader.zig");
     _ = @import("io/fixed_buffer_stream.zig");
     _ = @import("io/reader.zig");
     _ = @import("io/writer.zig");

lib/std/io/counting_reader.zig

@@ -12,37 +12,37 @@ pub fn CountingReader(comptime ReaderType: anytype) type {
     return struct {
         child_reader: ReaderType,
         bytes_read: u64 = 0,
-        
+
         pub const Error = ReaderType.Error;
         pub const Reader = io.Reader(*@This(), Error, read);
-        
+
         pub fn read(self: *@This(), buf: []u8) Error!usize {
             const amt = try self.child_reader.read(buf);
             self.bytes_read += amt;
             return amt;
         }
-        
+
         pub fn reader(self: *@This()) Reader {
             return .{ .context = self };
         }
     };
 }
 
 pub fn countingReader(reader: anytype) CountingReader(@TypeOf(reader)) {
-    return .{ .child_reader = reader, };
+    return .{ .child_reader = reader };
 }
 
 test "io.CountingReader" {
     const bytes = "yay" ** 100;
     var fbs = io.fixedBufferStream(bytes);
-    
+
     var counting_stream = countingReader(fbs.reader());
     const stream = counting_stream.reader();
-    
+
     //read and discard all bytes
-    while(stream.readByte()) |_| {} else |err| {
+    while (stream.readByte()) |_| {} else |err| {
         testing.expect(err == error.EndOfStream);
     }
-    
+
     testing.expect(counting_stream.bytes_read == bytes.len);
-}
+}