Reader.defaultDiscard: Fix for use with an indirect reader

If a Reader implementation implements `stream` by ignoring the Writer, writing directly to its internal buffer, and returning 0, then `defaultDiscard` would not update `seek` and also return 0, which is incorrect and can cause `discardShort` to violate the contract of `VTable.discard` by calling into `vtable.discard` with a non-empty buffer.

This commit fixes the problem by advancing seek up to the limit after the stream call. This logic could likely be somewhat simplified in the future depending on how #25170 is resolved.

.forgejo/workflows/ci.yaml

@@ -52,7 +52,7 @@ jobs:
         run: sh ci/loongarch64-linux-release.sh
         timeout-minutes: 180
   riscv64-linux-debug:
-    # if: github.event_name != 'pull_request'
+    if: github.event_name != 'pull_request'
     runs-on: [self-hosted, riscv64-linux]
     steps:
       - name: Checkout
@@ -63,7 +63,7 @@ jobs:
         run: sh ci/riscv64-linux-debug.sh
         timeout-minutes: 540
   riscv64-linux-release:
-    # if: github.event_name != 'pull_request'
+    if: github.event_name != 'pull_request'
     runs-on: [self-hosted, riscv64-linux]
     steps:
       - name: Checkout

doc/langref.html.in

@@ -421,8 +421,7 @@
       {#code|unattached_doc-comment.zig#}
 
       <p>
-      Doc comments can be interleaved with normal comments. Currently, when producing
+      Doc comments can be interleaved with normal comments, which are ignored.
-      the package documentation, normal comments are merged with doc comments.
       </p>
       {#header_close#}
       {#header_open|Top-Level Doc Comments#}

doc/langref/values.zig

@@ -4,6 +4,11 @@ const std = @import("std");
 const os = std.os;
 const assert = std.debug.assert;
 
+// Custom error set definition:
+const ExampleErrorSet = error{
+    ExampleErrorVariant,
+};
+
 pub fn main() void {
     // integers
     const one_plus_one: i32 = 1 + 1;
@@ -36,7 +41,7 @@ pub fn main() void {
     });
 
     // error union
-    var number_or_error: anyerror!i32 = error.ArgNotFound;
+    var number_or_error: ExampleErrorSet!i32 = ExampleErrorSet.ExampleErrorVariant;
 
     print("\nerror union 1\ntype: {}\nvalue: {!}\n", .{
         @TypeOf(number_or_error),

lib/std/Io.zig

@@ -580,6 +580,9 @@ pub const VTable = struct {
     /// If it returns `null` it means `result` has been already populated and
     /// `await` will be a no-op.
     ///
+    /// When this function returns non-null, the implementation guarantees that
+    /// a unit of concurrency has been assigned to the returned task.
+    ///
     /// Thread-safe.
     async: *const fn (
         /// Corresponds to `Io.userdata`.
@@ -1024,6 +1027,10 @@ pub const Group = struct {
     ///
     /// `function` *may* be called immediately, before `async` returns.
     ///
+    /// When this function returns, it is guaranteed that `function` has
+    /// already been called and completed, or it has successfully been assigned
+    /// a unit of concurrency.
+    ///
     /// After this is called, `wait` or `cancel` must be called before the
     /// group is deinitialized.
     ///
@@ -1094,6 +1101,10 @@ pub fn Select(comptime U: type) type {
         ///
         /// `function` *may* be called immediately, before `async` returns.
         ///
+        /// When this function returns, it is guaranteed that `function` has
+        /// already been called and completed, or it has successfully been
+        /// assigned a unit of concurrency.
+        ///
         /// After this is called, `wait` or `cancel` must be called before the
         /// select is deinitialized.
         ///
@@ -1524,8 +1535,11 @@ pub fn Queue(Elem: type) type {
 /// not guaranteed to be available until `await` is called.
 ///
 /// `function` *may* be called immediately, before `async` returns. This has
-/// weaker guarantees than `concurrent`, making more portable and
+/// weaker guarantees than `concurrent`, making more portable and reusable.
-/// reusable.
+///
+/// When this function returns, it is guaranteed that `function` has already
+/// been called and completed, or it has successfully been assigned a unit of
+/// concurrency.
 ///
 /// See also:
 /// * `Group`

lib/std/Io/Reader.zig

@@ -200,11 +200,17 @@ pub fn defaultDiscard(r: *Reader, limit: Limit) Error!usize {
     r.seek = 0;
     r.end = 0;
     var d: Writer.Discarding = .init(r.buffer);
-    const n = r.stream(&d.writer, limit) catch |err| switch (err) {
+    var n = r.stream(&d.writer, limit) catch |err| switch (err) {
         error.WriteFailed => unreachable,
         error.ReadFailed => return error.ReadFailed,
         error.EndOfStream => return error.EndOfStream,
     };
+    // If `stream` wrote to `r.buffer` without going through the writer,
+    // we need to discard as much of the buffered data as possible.
+    const remaining = @intFromEnum(limit) - n;
+    const buffered_n_to_discard = @min(remaining, r.end - r.seek);
+    n += buffered_n_to_discard;
+    r.seek += buffered_n_to_discard;
     assert(n <= @intFromEnum(limit));
     return n;
 }
@@ -1720,6 +1726,18 @@ fn failingDiscard(r: *Reader, limit: Limit) Error!usize {
     return error.ReadFailed;
 }
 
+test "discardAll that has to call discard multiple times on an indirect reader" {
+    var fr: Reader = .fixed("ABCDEFGHIJKLMNOPQRSTUVWXYZ");
+    var indirect_buffer: [3]u8 = undefined;
+    var tri: std.testing.ReaderIndirect = .init(&fr, &indirect_buffer);
+    const r = &tri.interface;
+
+    try r.discardAll(10);
+    var remaining_buf: [16]u8 = undefined;
+    try r.readSliceAll(&remaining_buf);
+    try std.testing.expectEqualStrings(fr.buffer[10..], remaining_buf[0..]);
+}
+
 test "readAlloc when the backing reader provides one byte at a time" {
     const str = "This is a test";
     var tiny_buffer: [1]u8 = undefined;

lib/std/Io/Threaded.zig

@@ -13,6 +13,7 @@ const net = std.Io.net;
 const HostName = std.Io.net.HostName;
 const IpAddress = std.Io.net.IpAddress;
 const Allocator = std.mem.Allocator;
+const Alignment = std.mem.Alignment;
 const assert = std.debug.assert;
 const posix = std.posix;
 
@@ -22,10 +23,30 @@ mutex: std.Thread.Mutex = .{},
 cond: std.Thread.Condition = .{},
 run_queue: std.SinglyLinkedList = .{},
 join_requested: bool = false,
-threads: std.ArrayList(std.Thread),
 stack_size: usize,
-cpu_count: std.Thread.CpuCountError!usize,
+/// All threads are spawned detached; this is how we wait until they all exit.
-concurrent_count: usize,
+wait_group: std.Thread.WaitGroup = .{},
+/// Maximum thread pool size (excluding main thread) when dispatching async
+/// tasks. Until this limit, calls to `Io.async` when all threads are busy will
+/// cause a new thread to be spawned and permanently added to the pool. After
+/// this limit, calls to `Io.async` when all threads are busy run the task
+/// immediately.
+///
+/// Defaults to a number equal to logical CPU cores.
+async_limit: Io.Limit,
+/// Maximum thread pool size (excluding main thread) for dispatching concurrent
+/// tasks. Until this limit, calls to `Io.concurrent` will increase the thread
+/// pool size.
+///
+/// concurrent tasks. After this number, calls to `Io.concurrent` return
+/// `error.ConcurrencyUnavailable`.
+concurrent_limit: Io.Limit = .unlimited,
+/// Error from calling `std.Thread.getCpuCount` in `init`.
+cpu_count_error: ?std.Thread.CpuCountError,
+/// Number of threads that are unavailable to take tasks. To calculate
+/// available count, subtract this from either `async_limit` or
+/// `concurrent_limit`.
+busy_count: usize = 0,
 
 wsa: if (is_windows) Wsa else struct {} = .{},
 
@@ -70,8 +91,6 @@ const Closure = struct {
     start: Start,
     node: std.SinglyLinkedList.Node = .{},
     cancel_tid: CancelId,
-    /// Whether this task bumps minimum number of threads in the pool.
-    is_concurrent: bool,
 
     const Start = *const fn (*Closure) void;
 
@@ -90,8 +109,6 @@ const Closure = struct {
     }
 };
 
-pub const InitError = std.Thread.CpuCountError || Allocator.Error;
-
 /// Related:
 /// * `init_single_threaded`
 pub fn init(
@@ -103,21 +120,20 @@ pub fn init(
     /// here.
     gpa: Allocator,
 ) Threaded {
+    if (builtin.single_threaded) return .init_single_threaded;
+
+    const cpu_count = std.Thread.getCpuCount();
+
     var t: Threaded = .{
         .allocator = gpa,
-        .threads = .empty,
         .stack_size = std.Thread.SpawnConfig.default_stack_size,
-        .cpu_count = std.Thread.getCpuCount(),
+        .async_limit = if (cpu_count) |n| .limited(n - 1) else |_| .nothing,
-        .concurrent_count = 0,
+        .cpu_count_error = if (cpu_count) |_| null else |e| e,
         .old_sig_io = undefined,
         .old_sig_pipe = undefined,
         .have_signal_handler = false,
     };
 
-    if (t.cpu_count) |n| {
-        t.threads.ensureTotalCapacityPrecise(gpa, n - 1) catch {};
-    } else |_| {}
-
     if (posix.Sigaction != void) {
         // This causes sending `posix.SIG.IO` to thread to interrupt blocking
         // syscalls, returning `posix.E.INTR`.
@@ -142,19 +158,17 @@ pub fn init(
 /// * `deinit` is safe, but unnecessary to call.
 pub const init_single_threaded: Threaded = .{
     .allocator = .failing,
-    .threads = .empty,
     .stack_size = std.Thread.SpawnConfig.default_stack_size,
-    .cpu_count = 1,
+    .async_limit = .nothing,
-    .concurrent_count = 0,
+    .cpu_count_error = null,
+    .concurrent_limit = .nothing,
     .old_sig_io = undefined,
     .old_sig_pipe = undefined,
     .have_signal_handler = false,
 };
 
 pub fn deinit(t: *Threaded) void {
-    const gpa = t.allocator;
     t.join();
-    t.threads.deinit(gpa);
     if (is_windows and t.wsa.status == .initialized) {
         if (ws2_32.WSACleanup() != 0) recoverableOsBugDetected();
     }
@@ -173,10 +187,12 @@ fn join(t: *Threaded) void {
         t.join_requested = true;
     }
     t.cond.broadcast();
-    for (t.threads.items) |thread| thread.join();
+    t.wait_group.wait();
 }
 
 fn worker(t: *Threaded) void {
+    defer t.wait_group.finish();
+
     t.mutex.lock();
     defer t.mutex.unlock();
 
@@ -184,12 +200,9 @@ fn worker(t: *Threaded) void {
         while (t.run_queue.popFirst()) |closure_node| {
             t.mutex.unlock();
             const closure: *Closure = @fieldParentPtr("node", closure_node);
-            const is_concurrent = closure.is_concurrent;
             closure.start(closure);
             t.mutex.lock();
-            if (is_concurrent) {
+            t.busy_count -= 1;
-                t.concurrent_count -= 1;
-            }
         }
         if (t.join_requested) break;
         t.cond.wait(&t.mutex);
@@ -387,7 +400,7 @@ const AsyncClosure = struct {
     func: *const fn (context: *anyopaque, result: *anyopaque) void,
     reset_event: ResetEvent,
     select_condition: ?*ResetEvent,
-    context_alignment: std.mem.Alignment,
+    context_alignment: Alignment,
     result_offset: usize,
     alloc_len: usize,
 
@@ -432,11 +445,10 @@ const AsyncClosure = struct {
 
     fn init(
         gpa: Allocator,
-        mode: enum { async, concurrent },
         result_len: usize,
-        result_alignment: std.mem.Alignment,
+        result_alignment: Alignment,
         context: []const u8,
-        context_alignment: std.mem.Alignment,
+        context_alignment: Alignment,
         func: *const fn (context: *const anyopaque, result: *anyopaque) void,
     ) Allocator.Error!*AsyncClosure {
         const max_context_misalignment = context_alignment.toByteUnits() -| @alignOf(AsyncClosure);
@@ -454,10 +466,6 @@ const AsyncClosure = struct {
             .closure = .{
                 .cancel_tid = .none,
                 .start = start,
-                .is_concurrent = switch (mode) {
-                    .async => false,
-                    .concurrent => true,
-                },
             },
             .func = func,
             .context_alignment = context_alignment,
@@ -470,10 +478,15 @@ const AsyncClosure = struct {
         return ac;
     }
 
-    fn waitAndDeinit(ac: *AsyncClosure, gpa: Allocator, result: []u8) void {
+    fn waitAndDeinit(ac: *AsyncClosure, t: *Threaded, result: []u8) void {
-        ac.reset_event.waitUncancelable();
+        ac.reset_event.wait(t) catch |err| switch (err) {
+            error.Canceled => {
+                ac.closure.requestCancel();
+                ac.reset_event.waitUncancelable();
+            },
+        };
         @memcpy(result, ac.resultPointer()[0..result.len]);
-        ac.deinit(gpa);
+        ac.deinit(t.allocator);
     }
 
     fn deinit(ac: *AsyncClosure, gpa: Allocator) void {
@@ -485,60 +498,50 @@ const AsyncClosure = struct {
 fn async(
     userdata: ?*anyopaque,
     result: []u8,
-    result_alignment: std.mem.Alignment,
+    result_alignment: Alignment,
     context: []const u8,
-    context_alignment: std.mem.Alignment,
+    context_alignment: Alignment,
     start: *const fn (context: *const anyopaque, result: *anyopaque) void,
 ) ?*Io.AnyFuture {
-    if (builtin.single_threaded) {
+    const t: *Threaded = @ptrCast(@alignCast(userdata));
+    if (builtin.single_threaded or t.async_limit == .nothing) {
         start(context.ptr, result.ptr);
         return null;
     }
-
-    const t: *Threaded = @ptrCast(@alignCast(userdata));
-    const cpu_count = t.cpu_count catch {
-        return concurrent(userdata, result.len, result_alignment, context, context_alignment, start) catch {
-            start(context.ptr, result.ptr);
-            return null;
-        };
-    };
-
     const gpa = t.allocator;
-    const ac = AsyncClosure.init(gpa, .async, result.len, result_alignment, context, context_alignment, start) catch {
+    const ac = AsyncClosure.init(gpa, result.len, result_alignment, context, context_alignment, start) catch {
         start(context.ptr, result.ptr);
         return null;
     };
 
     t.mutex.lock();
 
-    const thread_capacity = cpu_count - 1 + t.concurrent_count;
+    const busy_count = t.busy_count;
 
-    t.threads.ensureTotalCapacityPrecise(gpa, thread_capacity) catch {
+    if (busy_count >= @intFromEnum(t.async_limit)) {
         t.mutex.unlock();
         ac.deinit(gpa);
         start(context.ptr, result.ptr);
         return null;
-    };
-
-    t.run_queue.prepend(&ac.closure.node);
-
-    if (t.threads.items.len < thread_capacity) {
-        const thread = std.Thread.spawn(.{ .stack_size = t.stack_size }, worker, .{t}) catch {
-            if (t.threads.items.len == 0) {
-                assert(t.run_queue.popFirst() == &ac.closure.node);
-                t.mutex.unlock();
-                ac.deinit(gpa);
-                start(context.ptr, result.ptr);
-                return null;
-            }
-            // Rely on other workers to do it.
-            t.mutex.unlock();
-            t.cond.signal();
-            return @ptrCast(ac);
-        };
-        t.threads.appendAssumeCapacity(thread);
     }
 
+    t.busy_count = busy_count + 1;
+
+    const pool_size = t.wait_group.value();
+    if (pool_size - busy_count == 0) {
+        t.wait_group.start();
+        const thread = std.Thread.spawn(.{ .stack_size = t.stack_size }, worker, .{t}) catch {
+            t.wait_group.finish();
+            t.busy_count = busy_count;
+            t.mutex.unlock();
+            ac.deinit(gpa);
+            start(context.ptr, result.ptr);
+            return null;
+        };
+        thread.detach();
+    }
+
+    t.run_queue.prepend(&ac.closure.node);
     t.mutex.unlock();
     t.cond.signal();
     return @ptrCast(ac);
@@ -547,45 +550,42 @@ fn async(
 fn concurrent(
     userdata: ?*anyopaque,
     result_len: usize,
-    result_alignment: std.mem.Alignment,
+    result_alignment: Alignment,
     context: []const u8,
-    context_alignment: std.mem.Alignment,
+    context_alignment: Alignment,
     start: *const fn (context: *const anyopaque, result: *anyopaque) void,
 ) Io.ConcurrentError!*Io.AnyFuture {
     if (builtin.single_threaded) return error.ConcurrencyUnavailable;
 
     const t: *Threaded = @ptrCast(@alignCast(userdata));
-    const cpu_count = t.cpu_count catch 1;
 
     const gpa = t.allocator;
-    const ac = AsyncClosure.init(gpa, .concurrent, result_len, result_alignment, context, context_alignment, start) catch {
+    const ac = AsyncClosure.init(gpa, result_len, result_alignment, context, context_alignment, start) catch
         return error.ConcurrencyUnavailable;
-    };
+    errdefer ac.deinit(gpa);
 
     t.mutex.lock();
+    defer t.mutex.unlock();
 
-    t.concurrent_count += 1;
+    const busy_count = t.busy_count;
-    const thread_capacity = cpu_count - 1 + t.concurrent_count;
 
-    t.threads.ensureTotalCapacity(gpa, thread_capacity) catch {
+    if (busy_count >= @intFromEnum(t.concurrent_limit))
-        t.mutex.unlock();
-        ac.deinit(gpa);
         return error.ConcurrencyUnavailable;
-    };
 
-    t.run_queue.prepend(&ac.closure.node);
+    t.busy_count = busy_count + 1;
+    errdefer t.busy_count = busy_count;
 
-    if (t.threads.items.len < thread_capacity) {
+    const pool_size = t.wait_group.value();
-        const thread = std.Thread.spawn(.{ .stack_size = t.stack_size }, worker, .{t}) catch {
+    if (pool_size - busy_count == 0) {
-            assert(t.run_queue.popFirst() == &ac.closure.node);
+        t.wait_group.start();
-            t.mutex.unlock();
+        errdefer t.wait_group.finish();
-            ac.deinit(gpa);
+
+        const thread = std.Thread.spawn(.{ .stack_size = t.stack_size }, worker, .{t}) catch
             return error.ConcurrencyUnavailable;
-        };
+        thread.detach();
-        t.threads.appendAssumeCapacity(thread);
     }
 
-    t.mutex.unlock();
+    t.run_queue.prepend(&ac.closure.node);
     t.cond.signal();
     return @ptrCast(ac);
 }
@@ -597,7 +597,7 @@ const GroupClosure = struct {
     /// Points to sibling `GroupClosure`. Used for walking the group to cancel all.
     node: std.SinglyLinkedList.Node,
     func: *const fn (*Io.Group, context: *anyopaque) void,
-    context_alignment: std.mem.Alignment,
+    context_alignment: Alignment,
     alloc_len: usize,
 
     fn start(closure: *Closure) void {
@@ -638,7 +638,7 @@ const GroupClosure = struct {
         t: *Threaded,
         group: *Io.Group,
         context: []const u8,
-        context_alignment: std.mem.Alignment,
+        context_alignment: Alignment,
         func: *const fn (*Io.Group, context: *const anyopaque) void,
     ) Allocator.Error!*GroupClosure {
         const max_context_misalignment = context_alignment.toByteUnits() -| @alignOf(GroupClosure);
@@ -652,7 +652,6 @@ const GroupClosure = struct {
             .closure = .{
                 .cancel_tid = .none,
                 .start = start,
-                .is_concurrent = false,
             },
             .t = t,
             .group = group,
@@ -678,45 +677,48 @@ fn groupAsync(
     userdata: ?*anyopaque,
     group: *Io.Group,
     context: []const u8,
-    context_alignment: std.mem.Alignment,
+    context_alignment: Alignment,
     start: *const fn (*Io.Group, context: *const anyopaque) void,
 ) void {
-    if (builtin.single_threaded) return start(group, context.ptr);
-
     const t: *Threaded = @ptrCast(@alignCast(userdata));
-    const cpu_count = t.cpu_count catch 1;
+    if (builtin.single_threaded or t.async_limit == .nothing)
+        return start(group, context.ptr);
 
     const gpa = t.allocator;
-    const gc = GroupClosure.init(gpa, t, group, context, context_alignment, start) catch {
+    const gc = GroupClosure.init(gpa, t, group, context, context_alignment, start) catch
         return start(group, context.ptr);
-    };
 
     t.mutex.lock();
 
+    const busy_count = t.busy_count;
+
+    if (busy_count >= @intFromEnum(t.async_limit)) {
+        t.mutex.unlock();
+        gc.deinit(gpa);
+        return start(group, context.ptr);
+    }
+
+    t.busy_count = busy_count + 1;
+
+    const pool_size = t.wait_group.value();
+    if (pool_size - busy_count == 0) {
+        t.wait_group.start();
+        const thread = std.Thread.spawn(.{ .stack_size = t.stack_size }, worker, .{t}) catch {
+            t.wait_group.finish();
+            t.busy_count = busy_count;
+            t.mutex.unlock();
+            gc.deinit(gpa);
+            return start(group, context.ptr);
+        };
+        thread.detach();
+    }
+
     // Append to the group linked list inside the mutex to make `Io.Group.async` thread-safe.
     gc.node = .{ .next = @ptrCast(@alignCast(group.token)) };
     group.token = &gc.node;
 
-    const thread_capacity = cpu_count - 1 + t.concurrent_count;
-
-    t.threads.ensureTotalCapacityPrecise(gpa, thread_capacity) catch {
-        t.mutex.unlock();
-        gc.deinit(gpa);
-        return start(group, context.ptr);
-    };
-
     t.run_queue.prepend(&gc.closure.node);
 
-    if (t.threads.items.len < thread_capacity) {
-        const thread = std.Thread.spawn(.{ .stack_size = t.stack_size }, worker, .{t}) catch {
-            assert(t.run_queue.popFirst() == &gc.closure.node);
-            t.mutex.unlock();
-            gc.deinit(gpa);
-            return start(group, context.ptr);
-        };
-        t.threads.appendAssumeCapacity(thread);
-    }
-
     // This needs to be done before unlocking the mutex to avoid a race with
     // the associated task finishing.
     const group_state: *std.atomic.Value(usize) = @ptrCast(&group.state);
@@ -794,25 +796,25 @@ fn await(
     userdata: ?*anyopaque,
     any_future: *Io.AnyFuture,
     result: []u8,
-    result_alignment: std.mem.Alignment,
+    result_alignment: Alignment,
 ) void {
     _ = result_alignment;
     const t: *Threaded = @ptrCast(@alignCast(userdata));
     const closure: *AsyncClosure = @ptrCast(@alignCast(any_future));
-    closure.waitAndDeinit(t.allocator, result);
+    closure.waitAndDeinit(t, result);
 }
 
 fn cancel(
     userdata: ?*anyopaque,
     any_future: *Io.AnyFuture,
     result: []u8,
-    result_alignment: std.mem.Alignment,
+    result_alignment: Alignment,
 ) void {
     _ = result_alignment;
     const t: *Threaded = @ptrCast(@alignCast(userdata));
     const ac: *AsyncClosure = @ptrCast(@alignCast(any_future));
     ac.closure.requestCancel();
-    ac.waitAndDeinit(t.allocator, result);
+    ac.waitAndDeinit(t, result);
 }
 
 fn cancelRequested(userdata: ?*anyopaque) bool {

lib/std/Io/Threaded/test.zig

@@ -10,7 +10,7 @@ test "concurrent vs main prevents deadlock via oversubscription" {
     defer threaded.deinit();
     const io = threaded.io();
 
-    threaded.cpu_count = 1;
+    threaded.async_limit = .nothing;
 
     var queue: Io.Queue(u8) = .init(&.{});
 
@@ -38,7 +38,7 @@ test "concurrent vs concurrent prevents deadlock via oversubscription" {
     defer threaded.deinit();
     const io = threaded.io();
 
-    threaded.cpu_count = 1;
+    threaded.async_limit = .nothing;
 
     var queue: Io.Queue(u8) = .init(&.{});
 

lib/std/Thread.zig

@@ -1,13 +1,14 @@
-//! This struct represents a kernel thread, and acts as a namespace for concurrency
+//! This struct represents a kernel thread, and acts as a namespace for
-//! primitives that operate on kernel threads. For concurrency primitives that support
+//! concurrency primitives that operate on kernel threads. For concurrency
-//! both evented I/O and async I/O, see the respective names in the top level std namespace.
+//! primitives that interact with the I/O interface, see `std.Io`.
 
-const std = @import("std.zig");
 const builtin = @import("builtin");
-const math = std.math;
-const assert = std.debug.assert;
 const target = builtin.target;
 const native_os = builtin.os.tag;
+
+const std = @import("std.zig");
+const math = std.math;
+const assert = std.debug.assert;
 const posix = std.posix;
 const windows = std.os.windows;
 const testing = std.testing;

lib/std/Thread/WaitGroup.zig

@@ -60,6 +60,10 @@ pub fn isDone(wg: *WaitGroup) bool {
     return (state / one_pending) == 0;
 }
 
+pub fn value(wg: *WaitGroup) usize {
+    return wg.state.load(.monotonic) / one_pending;
+}
+
 // Spawns a new thread for the task. This is appropriate when the callee
 // delegates all work.
 pub fn spawnManager(

lib/std/crypto/benchmark.zig

@@ -30,7 +30,6 @@ const hashes = [_]Crypto{
     Crypto{ .ty = crypto.hash.sha3.Shake256, .name = "shake-256" },
     Crypto{ .ty = crypto.hash.sha3.TurboShake128(null), .name = "turboshake-128" },
     Crypto{ .ty = crypto.hash.sha3.TurboShake256(null), .name = "turboshake-256" },
-    Crypto{ .ty = crypto.hash.sha3.KT128, .name = "kt128" },
     Crypto{ .ty = crypto.hash.blake2.Blake2s256, .name = "blake2s" },
     Crypto{ .ty = crypto.hash.blake2.Blake2b512, .name = "blake2b" },
     Crypto{ .ty = crypto.hash.Blake3, .name = "blake3" },
@@ -38,7 +37,6 @@ const hashes = [_]Crypto{
 
 const parallel_hashes = [_]Crypto{
     Crypto{ .ty = crypto.hash.Blake3, .name = "blake3-parallel" },
-    Crypto{ .ty = crypto.hash.sha3.KT128, .name = "kt128-parallel" },
 };
 
 const block_size: usize = 8 * 8192;

lib/std/crypto/blake3.zig

@@ -12,8 +12,8 @@ const Vec16 = @Vector(16, u32);
 const chunk_length = 1024;
 const max_depth = 54;
 
-const simd_degree = std.simd.suggestVectorLength(u32) orelse 1;
+pub const simd_degree = std.simd.suggestVectorLength(u32) orelse 1;
-const max_simd_degree = simd_degree;
+pub const max_simd_degree = simd_degree;
 const max_simd_degree_or_2 = if (max_simd_degree > 2) max_simd_degree else 2;
 
 /// Threshold for switching to parallel processing.
@@ -502,7 +502,9 @@ fn hashManySimd(
     var out_ptr = out.ptr;
     var cnt = counter;
 
-    if (simd_degree >= 16) {
+    const simd_deg = comptime simd_degree;
+
+    if (comptime simd_deg >= 16) {
         while (remaining >= 16) {
             const sixteen_inputs = [16][*]const u8{
                 inp[0],  inp[1],  inp[2],  inp[3],
@@ -523,7 +525,7 @@ fn hashManySimd(
         }
     }
 
-    if (simd_degree >= 8) {
+    if (comptime simd_deg >= 8) {
         while (remaining >= 8) {
             const eight_inputs = [8][*]const u8{
                 inp[0], inp[1], inp[2], inp[3],
@@ -542,7 +544,7 @@ fn hashManySimd(
         }
     }
 
-    if (simd_degree >= 4) {
+    if (comptime simd_deg >= 4) {
         while (remaining >= 4) {
             const four_inputs = [4][*]const u8{
                 inp[0],
@@ -569,7 +571,7 @@ fn hashManySimd(
 }
 
 fn hashMany(inputs: [][*]const u8, num_inputs: usize, blocks: usize, key: [8]u32, counter: u64, increment_counter: bool, flags: Flags, flags_start: Flags, flags_end: Flags, out: []u8) void {
-    if (max_simd_degree >= 4) {
+    if (comptime max_simd_degree >= 4) {
         hashManySimd(inputs, num_inputs, blocks, key, counter, increment_counter, flags, flags_start, flags_end, out);
     } else {
         hashManyPortable(inputs, num_inputs, blocks, key, counter, increment_counter, flags, flags_start, flags_end, out);
@@ -907,7 +909,7 @@ pub const Blake3 = struct {
     pub const digest_length = 32;
     pub const key_length = 32;
 
-    pub const Options = struct { key: ?[key_length]u8 = null };
+    pub const Options = struct { key: ?[digest_length]u8 = null };
     pub const KdfOptions = struct {};
 
     key: [8]u32,

lib/std/crypto/sha3.zig

@@ -4,8 +4,6 @@ const assert = std.debug.assert;
 const math = std.math;
 const mem = std.mem;
 
-const kangarootwelve = @import("kangarootwelve.zig");
-
 const KeccakState = std.crypto.core.keccak.State;
 
 pub const Sha3_224 = Keccak(1600, 224, 0x06, 24);
@@ -28,9 +26,6 @@ pub const KMac256 = KMac(256);
 pub const TupleHash128 = TupleHash(128);
 pub const TupleHash256 = TupleHash(256);
 
-pub const KT128 = kangarootwelve.KT128;
-pub const KT256 = kangarootwelve.KT256;
-
 /// TurboSHAKE128 is a XOF (a secure hash function with a variable output length), with a 128 bit security level.
 /// It is based on the same permutation as SHA3 and SHAKE128, but which much higher performance.
 /// The delimiter is 0x1f by default, but can be changed for context-separation.
@@ -486,10 +481,6 @@ pub const NistLengthEncoding = enum {
 
 const htest = @import("test.zig");
 
-test {
-    _ = kangarootwelve;
-}
-
 test "sha3-224 single" {
     try htest.assertEqualHash(Sha3_224, "6b4e03423667dbb73b6e15454f0eb1abd4597f9a1b078e3f5b5a6bc7", "");
     try htest.assertEqualHash(Sha3_224, "e642824c3f8cf24ad09234ee7d3c766fc9a3a5168d0c94ad73b46fdf", "abc");

test/incremental/add_decl

@@ -1,63 +0,0 @@
-#target=x86_64-linux-selfhosted
-#target=x86_64-windows-selfhosted
-#target=x86_64-linux-cbe
-#target=x86_64-windows-cbe
-//#target=wasm32-wasi-selfhosted
-#update=initial version
-#file=main.zig
-const std = @import("std");
-pub fn main() !void {
-    try std.fs.File.stdout().writeAll(foo);
-}
-const foo = "good morning\n";
-#expect_stdout="good morning\n"
-
-#update=add new declaration
-#file=main.zig
-const std = @import("std");
-pub fn main() !void {
-    try std.fs.File.stdout().writeAll(foo);
-}
-const foo = "good morning\n";
-const bar = "good evening\n";
-#expect_stdout="good morning\n"
-
-#update=reference new declaration
-#file=main.zig
-const std = @import("std");
-pub fn main() !void {
-    try std.fs.File.stdout().writeAll(bar);
-}
-const foo = "good morning\n";
-const bar = "good evening\n";
-#expect_stdout="good evening\n"
-
-#update=reference missing declaration
-#file=main.zig
-const std = @import("std");
-pub fn main() !void {
-    try std.fs.File.stdout().writeAll(qux);
-}
-const foo = "good morning\n";
-const bar = "good evening\n";
-#expect_error=main.zig:3:39: error: use of undeclared identifier 'qux'
-
-#update=add missing declaration
-#file=main.zig
-const std = @import("std");
-pub fn main() !void {
-    try std.fs.File.stdout().writeAll(qux);
-}
-const foo = "good morning\n";
-const bar = "good evening\n";
-const qux = "good night\n";
-#expect_stdout="good night\n"
-
-#update=remove unused declarations
-#file=main.zig
-const std = @import("std");
-pub fn main() !void {
-    try std.fs.File.stdout().writeAll(qux);
-}
-const qux = "good night\n";
-#expect_stdout="good night\n"