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Jul 8, 2025
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remove async and await keywords; remove usingnamespace #24362

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40d11cc
remove `async` and `await` keywords
andrewrk Jul 7, 2025
a59c35c
build.zig: bump maxrss for behavior tests
andrewrk Jul 7, 2025
aa52bb8
zig fmt
andrewrk Jul 7, 2025
34f6443
remove `usingnamespace` from the language
andrewrk Jul 7, 2025
4ba0e7d
update zig1.wasm
andrewrk Jul 7, 2025
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4 changes: 2 additions & 2 deletions build.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -460,8 +460,8 @@ pub fn build(b: *std.Build) !void {
.skip_linux = skip_linux,
.skip_llvm = skip_llvm,
.skip_libc = skip_libc,
// 2923515904 was observed on an x86_64-linux-gnu host.
.max_rss = 3100000000,
// 3888779264 was observed on an x86_64-linux-gnu host.
.max_rss = 4000000000,
}));

test_modules_step.dependOn(tests.addModuleTests(b, .{
Expand Down
95 changes: 8 additions & 87 deletions doc/langref.html.in
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Expand Up @@ -3842,37 +3842,6 @@ void do_a_thing(struct Foo *foo) {
{#header_close#}
{#header_close#}

{#header_open|usingnamespace#}
<p>
{#syntax#}usingnamespace{#endsyntax#} is a declaration that mixes all the public
declarations of the operand, which must be a {#link|struct#}, {#link|union#}, {#link|enum#},
or {#link|opaque#}, into the namespace:
</p>
{#code|test_usingnamespace.zig#}

<p>
{#syntax#}usingnamespace{#endsyntax#} has an important use case when organizing the public
API of a file or package. For example, one might have <code class="file">c.zig</code> with all of the
{#link|C imports|Import from C Header File#}:
</p>
{#syntax_block|zig|c.zig#}
pub usingnamespace @cImport({
@cInclude("epoxy/gl.h");
@cInclude("GLFW/glfw3.h");
@cDefine("STBI_ONLY_PNG", "");
@cDefine("STBI_NO_STDIO", "");
@cInclude("stb_image.h");
});
{#end_syntax_block#}
<p>
The above example demonstrates using {#syntax#}pub{#endsyntax#} to qualify the
{#syntax#}usingnamespace{#endsyntax#} additionally makes the imported declarations
{#syntax#}pub{#endsyntax#}. This can be used to forward declarations, giving precise control
over what declarations a given file exposes.
</p>
{#header_close#}


{#header_open|comptime#}
<p>
Zig places importance on the concept of whether an expression is known at compile-time.
Expand Down Expand Up @@ -4279,16 +4248,9 @@ pub fn print(self: *Writer, arg0: []const u8, arg1: i32) !void {
{#header_close#}

{#header_open|Async Functions#}
<p>Async functions regressed with the release of 0.11.0. Their future in
the Zig language is unclear due to multiple unsolved problems:</p>
<ul>
<li>LLVM's lack of ability to optimize them.</li>
<li>Third-party debuggers' lack of ability to debug them.</li>
<li><a href="https://github.com/ziglang/zig/issues/5913">The cancellation problem</a>.</li>
<li>Async function pointers preventing the stack size from being known.</li>
</ul>
<p>These problems are surmountable, but it will take time. The Zig team
is currently focused on other priorities.</p>
<p>Async functions regressed with the release of 0.11.0. The current plan is to
reintroduce them as a lower level primitive that powers I/O implementations.</p>
<p>Tracking issue: <a href="https://github.com/ziglang/zig/issues/23446">Proposal: stackless coroutines as low-level primitives</a></p>
{#header_close#}

{#header_open|Builtin Functions|2col#}
Expand Down Expand Up @@ -6552,7 +6514,7 @@ fn cmpxchgWeakButNotAtomic(comptime T: type, ptr: *T, expected_value: T, new_val
</p>
<ul>
<li>If a call to {#syntax#}@import{#endsyntax#} is analyzed, the file being imported is analyzed.</li>
<li>If a type (including a file) is analyzed, all {#syntax#}comptime{#endsyntax#}, {#syntax#}usingnamespace{#endsyntax#}, and {#syntax#}export{#endsyntax#} declarations within it are analyzed.</li>
<li>If a type (including a file) is analyzed, all {#syntax#}comptime{#endsyntax#} and {#syntax#}export{#endsyntax#} declarations within it are analyzed.</li>
<li>If a type (including a file) is analyzed, and the compilation is for a {#link|test|Zig Test#}, and the module the type is within is the root module of the compilation, then all {#syntax#}test{#endsyntax#} declarations within it are also analyzed.</li>
<li>If a reference to a named declaration (i.e. a usage of it) is analyzed, the declaration being referenced is analyzed. Declarations are order-independent, so this reference may be above or below the declaration being referenced, or even in another file entirely.</li>
</ul>
Expand Down Expand Up @@ -7372,29 +7334,6 @@ fn readU32Be() u32 {}
</ul>
</td>
</tr>
<tr>
<th scope="row">
<pre>{#syntax#}async{#endsyntax#}</pre>
</th>
<td>
{#syntax#}async{#endsyntax#} can be used before a function call to get a pointer to the function's frame when it suspends.
<ul>
<li>See also {#link|Async Functions#}</li>
</ul>
</td>
</tr>
<tr>
<th scope="row">
<pre>{#syntax#}await{#endsyntax#}</pre>
</th>
<td>
{#syntax#}await{#endsyntax#} can be used to suspend the current function until the frame provided after the {#syntax#}await{#endsyntax#} completes.
{#syntax#}await{#endsyntax#} copies the value returned from the target function's frame to the caller.
<ul>
<li>See also {#link|Async Functions#}</li>
</ul>
</td>
</tr>
<tr>
<th scope="row">
<pre>{#syntax#}break{#endsyntax#}</pre>
Expand Down Expand Up @@ -7812,18 +7751,6 @@ fn readU32Be() u32 {}
</ul>
</td>
</tr>
<tr>
<th scope="row">
<pre>{#syntax#}usingnamespace{#endsyntax#}</pre>
</th>
<td>
{#syntax#}usingnamespace{#endsyntax#} is a top-level declaration that imports all the public declarations of the operand,
which must be a struct, union, or enum, into the current scope.
<ul>
<li>See also {#link|usingnamespace#}</li>
</ul>
</td>
</tr>
<tr>
<th scope="row">
<pre>{#syntax#}var{#endsyntax#}</pre>
Expand Down Expand Up @@ -7893,7 +7820,6 @@ ComptimeDecl <- KEYWORD_comptime Block
Decl
<- (KEYWORD_export / KEYWORD_extern STRINGLITERALSINGLE? / KEYWORD_inline / KEYWORD_noinline)? FnProto (SEMICOLON / Block)
/ (KEYWORD_export / KEYWORD_extern STRINGLITERALSINGLE?)? KEYWORD_threadlocal? GlobalVarDecl
/ KEYWORD_usingnamespace Expr SEMICOLON

FnProto <- KEYWORD_fn IDENTIFIER? LPAREN ParamDeclList RPAREN ByteAlign? AddrSpace? LinkSection? CallConv? EXCLAMATIONMARK? TypeExpr

Expand Down Expand Up @@ -8006,8 +7932,7 @@ TypeExpr <- PrefixTypeOp* ErrorUnionExpr
ErrorUnionExpr <- SuffixExpr (EXCLAMATIONMARK TypeExpr)?

SuffixExpr
<- KEYWORD_async PrimaryTypeExpr SuffixOp* FnCallArguments
/ PrimaryTypeExpr (SuffixOp / FnCallArguments)*
<- PrimaryTypeExpr (SuffixOp / FnCallArguments)*

PrimaryTypeExpr
<- BUILTINIDENTIFIER FnCallArguments
Expand Down Expand Up @@ -8183,7 +8108,6 @@ PrefixOp
/ MINUSPERCENT
/ AMPERSAND
/ KEYWORD_try
/ KEYWORD_await

PrefixTypeOp
<- QUESTIONMARK
Expand Down Expand Up @@ -8404,8 +8328,6 @@ KEYWORD_and <- 'and' end_of_word
KEYWORD_anyframe <- 'anyframe' end_of_word
KEYWORD_anytype <- 'anytype' end_of_word
KEYWORD_asm <- 'asm' end_of_word
KEYWORD_async <- 'async' end_of_word
KEYWORD_await <- 'await' end_of_word
KEYWORD_break <- 'break' end_of_word
KEYWORD_callconv <- 'callconv' end_of_word
KEYWORD_catch <- 'catch' end_of_word
Expand Down Expand Up @@ -8442,14 +8364,13 @@ KEYWORD_threadlocal <- 'threadlocal' end_of_word
KEYWORD_try <- 'try' end_of_word
KEYWORD_union <- 'union' end_of_word
KEYWORD_unreachable <- 'unreachable' end_of_word
KEYWORD_usingnamespace <- 'usingnamespace' end_of_word
KEYWORD_var <- 'var' end_of_word
KEYWORD_volatile <- 'volatile' end_of_word
KEYWORD_while <- 'while' end_of_word

keyword <- KEYWORD_addrspace / KEYWORD_align / KEYWORD_allowzero / KEYWORD_and
/ KEYWORD_anyframe / KEYWORD_anytype / KEYWORD_asm / KEYWORD_async
/ KEYWORD_await / KEYWORD_break / KEYWORD_callconv / KEYWORD_catch
/ KEYWORD_anyframe / KEYWORD_anytype / KEYWORD_asm
/ KEYWORD_break / KEYWORD_callconv / KEYWORD_catch
/ KEYWORD_comptime / KEYWORD_const / KEYWORD_continue / KEYWORD_defer
/ KEYWORD_else / KEYWORD_enum / KEYWORD_errdefer / KEYWORD_error / KEYWORD_export
/ KEYWORD_extern / KEYWORD_fn / KEYWORD_for / KEYWORD_if
Expand All @@ -8458,7 +8379,7 @@ keyword <- KEYWORD_addrspace / KEYWORD_align / KEYWORD_allowzero / KEYWORD_and
/ KEYWORD_pub / KEYWORD_resume / KEYWORD_return / KEYWORD_linksection
/ KEYWORD_struct / KEYWORD_suspend / KEYWORD_switch / KEYWORD_test
/ KEYWORD_threadlocal / KEYWORD_try / KEYWORD_union / KEYWORD_unreachable
/ KEYWORD_usingnamespace / KEYWORD_var / KEYWORD_volatile / KEYWORD_while
/ KEYWORD_var / KEYWORD_volatile / KEYWORD_while
{#end_syntax_block#}
{#header_close#}
{#header_open|Zen#}
Expand Down
8 changes: 0 additions & 8 deletions doc/langref/test_usingnamespace.zig
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This file was deleted.

12 changes: 0 additions & 12 deletions lib/compiler/reduce/Walk.zig
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Expand Up @@ -160,12 +160,6 @@ fn walkMember(w: *Walk, decl: Ast.Node.Index) Error!void {
try walkExpression(w, decl);
},

.@"usingnamespace" => {
try w.transformations.append(.{ .delete_node = decl });
const expr = ast.nodeData(decl).node;
try walkExpression(w, expr);
},

.global_var_decl,
.local_var_decl,
.simple_var_decl,
Expand Down Expand Up @@ -335,7 +329,6 @@ fn walkExpression(w: *Walk, node: Ast.Node.Index) Error!void {
.address_of,
.@"try",
.@"resume",
.@"await",
.deref,
=> {
return walkExpression(w, ast.nodeData(node).node);
Expand Down Expand Up @@ -379,12 +372,8 @@ fn walkExpression(w: *Walk, node: Ast.Node.Index) Error!void {

.call_one,
.call_one_comma,
.async_call_one,
.async_call_one_comma,
.call,
.call_comma,
.async_call,
.async_call_comma,
=> {
var buf: [1]Ast.Node.Index = undefined;
return walkCall(w, ast.fullCall(&buf, node).?);
Expand Down Expand Up @@ -525,7 +514,6 @@ fn walkExpression(w: *Walk, node: Ast.Node.Index) Error!void {
.local_var_decl => unreachable,
.simple_var_decl => unreachable,
.aligned_var_decl => unreachable,
.@"usingnamespace" => unreachable,
.test_decl => unreachable,
.asm_output => unreachable,
.asm_input => unreachable,
Expand Down
11 changes: 0 additions & 11 deletions lib/docs/wasm/Walk.zig
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Expand Up @@ -238,12 +238,8 @@ pub const File = struct {

.call_one,
.call_one_comma,
.async_call_one,
.async_call_one_comma,
.call,
.call_comma,
.async_call,
.async_call_comma,
=> {
var buf: [1]Ast.Node.Index = undefined;
return categorize_call(file_index, node, ast.fullCall(&buf, node).?);
Expand Down Expand Up @@ -571,7 +567,6 @@ fn struct_decl(
},

.@"comptime",
.@"usingnamespace",
=> try w.expr(&namespace.base, parent_decl, ast.nodeData(member).node),

.test_decl => try w.expr(&namespace.base, parent_decl, ast.nodeData(member).opt_token_and_node[1]),
Expand Down Expand Up @@ -643,7 +638,6 @@ fn expr(w: *Walk, scope: *Scope, parent_decl: Decl.Index, node: Ast.Node.Index)
const ast = w.file.get_ast();
switch (ast.nodeTag(node)) {
.root => unreachable, // Top-level declaration.
.@"usingnamespace" => unreachable, // Top-level declaration.
.test_decl => unreachable, // Top-level declaration.
.container_field_init => unreachable, // Top-level declaration.
.container_field_align => unreachable, // Top-level declaration.
Expand Down Expand Up @@ -743,7 +737,6 @@ fn expr(w: *Walk, scope: *Scope, parent_decl: Decl.Index, node: Ast.Node.Index)
.@"comptime",
.@"nosuspend",
.@"suspend",
.@"await",
.@"resume",
.@"try",
=> try expr(w, scope, parent_decl, ast.nodeData(node).node),
Expand Down Expand Up @@ -806,12 +799,8 @@ fn expr(w: *Walk, scope: *Scope, parent_decl: Decl.Index, node: Ast.Node.Index)

.call_one,
.call_one_comma,
.async_call_one,
.async_call_one_comma,
.call,
.call_comma,
.async_call,
.async_call_comma,
=> {
var buf: [1]Ast.Node.Index = undefined;
const full = ast.fullCall(&buf, node).?;
Expand Down
3 changes: 0 additions & 3 deletions lib/docs/wasm/html_render.zig
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Expand Up @@ -101,8 +101,6 @@ pub fn fileSourceHtml(
.keyword_align,
.keyword_and,
.keyword_asm,
.keyword_async,
.keyword_await,
.keyword_break,
.keyword_catch,
.keyword_comptime,
Expand Down Expand Up @@ -139,7 +137,6 @@ pub fn fileSourceHtml(
.keyword_try,
.keyword_union,
.keyword_unreachable,
.keyword_usingnamespace,
.keyword_var,
.keyword_volatile,
.keyword_allowzero,
Expand Down
2 changes: 1 addition & 1 deletion lib/std/Build/Module.zig
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Expand Up @@ -572,7 +572,7 @@ pub fn appendZigProcessFlags(
try zig_args.append(switch (unwind_tables) {
.none => "-fno-unwind-tables",
.sync => "-funwind-tables",
.@"async" => "-fasync-unwind-tables",
.async => "-fasync-unwind-tables",
});
}

Expand Down
2 changes: 1 addition & 1 deletion lib/std/Target.zig
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Expand Up @@ -1691,7 +1691,7 @@ pub const Cpu = struct {
pub fn fromCallingConvention(cc: std.builtin.CallingConvention.Tag) []const Arch {
return switch (cc) {
.auto,
.@"async",
.async,
.naked,
.@"inline",
=> unreachable,
Expand Down
17 changes: 3 additions & 14 deletions lib/std/builtin.zig
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Expand Up @@ -199,8 +199,6 @@ pub const CallingConvention = union(enum(u8)) {
pub const C: CallingConvention = .c;
/// Deprecated; use `.naked`.
pub const Naked: CallingConvention = .naked;
/// Deprecated; use `.@"async"`.
pub const Async: CallingConvention = .@"async";
/// Deprecated; use `.@"inline"`.
pub const Inline: CallingConvention = .@"inline";
/// Deprecated; use `.x86_64_interrupt`, `.x86_interrupt`, or `.avr_interrupt`.
Expand Down Expand Up @@ -248,7 +246,7 @@ pub const CallingConvention = union(enum(u8)) {
/// The calling convention of a function that can be called with `async` syntax. An `async` call
/// of a runtime-known function must target a function with this calling convention.
/// Comptime-known functions with other calling conventions may be coerced to this one.
@"async",
async,
Comment on lines 246 to +249
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@alexrp alexrp Jul 7, 2025

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Since you're doing a zig1.wasm update anyway, maybe worth taking the opportunity to remove this?

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@andrewrk andrewrk Jul 7, 2025

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That very likely will need to stay no matter how #23446 is resolved.

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@alexrp alexrp Jul 7, 2025

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That proposal says:

An async function must have callconv(.auto).

That's what made me think that CallingConvention.async would go away, since this is explicitly unlike inline and callconv(.@"inline") which are both allowed and equivalent. cc @mlugg

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@andrewrk andrewrk Jul 7, 2025

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I doubt that proposal will be accepted as-is.


/// Functions with this calling convention have no prologue or epilogue, making the function
/// uncallable in regular Zig code. This can be useful when integrating with assembly.
Expand Down Expand Up @@ -851,7 +849,7 @@ pub const LinkMode = enum {
pub const UnwindTables = enum {
none,
sync,
@"async",
async,
};

/// This data structure is used by the Zig language code generation and
Expand All @@ -866,32 +864,23 @@ pub const WasiExecModel = enum {
pub const CallModifier = enum {
/// Equivalent to function call syntax.
auto,

/// Equivalent to async keyword used with function call syntax.
async_kw,

/// Prevents tail call optimization. This guarantees that the return
/// address will point to the callsite, as opposed to the callsite's
/// callsite. If the call is otherwise required to be tail-called
/// or inlined, a compile error is emitted instead.
never_tail,

/// Guarantees that the call will not be inlined. If the call is
/// otherwise required to be inlined, a compile error is emitted instead.
never_inline,

/// Asserts that the function call will not suspend. This allows a
/// non-async function to call an async function.
no_async,

no_suspend,
/// Guarantees that the call will be generated with tail call optimization.
/// If this is not possible, a compile error is emitted instead.
always_tail,

/// Guarantees that the call will be inlined at the callsite.
/// If this is not possible, a compile error is emitted instead.
always_inline,

/// Evaluates the call at compile-time. If the call cannot be completed at
/// compile-time, a compile error is emitted instead.
compile_time,
Expand Down
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