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langref: update to new cast builtin syntax

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mlugg 2023-06-23 19:37:50 +01:00 • committed by Andrew Kelley
parent f26dda2117
commit a84a895325
1 changed files with 65 additions and 59 deletions
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124
doc/langref.html.in
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@ -2410,7 +2410,7 @@ var some_integers: [100]i32 = undefined;
test "modify an array" {
for (&some_integers, 0..) |*item, i| {
item.* = @intCast(i32, i);
item.* = @intCast(i);
}
try expect(some_integers[10] == 10);
try expect(some_integers[99] == 99);
@ -2452,8 +2452,8 @@ var fancy_array = init: {
var initial_value: [10]Point = undefined;
for (&initial_value, 0..) |*pt, i| {
pt.* = Point{
.x = @intCast(i32, i),
.y = @intCast(i32, i) * 2,
.x = @intCast(i),
.y = @intCast(i * 2),
};
}
break :init initial_value;
@ -2769,7 +2769,7 @@ test "comptime pointers" {
const expect = @import("std").testing.expect;
test "@intFromPtr and @ptrFromInt" {
const ptr = @ptrFromInt(*i32, 0xdeadbee0);
const ptr: *i32 = @ptrFromInt(0xdeadbee0);
const addr = @intFromPtr(ptr);
try expect(@TypeOf(addr) == usize);
try expect(addr == 0xdeadbee0);
@ -2784,7 +2784,7 @@ test "comptime @ptrFromInt" {
comptime {
// Zig is able to do this at compile-time, as long as
// ptr is never dereferenced.
const ptr = @ptrFromInt(*i32, 0xdeadbee0);
const ptr: *i32 = @ptrFromInt(0xdeadbee0);
const addr = @intFromPtr(ptr);
try expect(@TypeOf(addr) == usize);
try expect(addr == 0xdeadbee0);
@ -2801,7 +2801,7 @@ test "comptime @ptrFromInt" {
const expect = @import("std").testing.expect;
test "volatile" {
const mmio_ptr = @ptrFromInt(*volatile u8, 0x12345678);
const mmio_ptr: *volatile u8 = @ptrFromInt(0x12345678);
try expect(@TypeOf(mmio_ptr) == *volatile u8);
}
{#code_end#}
@ -2822,7 +2822,7 @@ const expect = std.testing.expect;
test "pointer casting" {
const bytes align(@alignOf(u32)) = [_]u8{ 0x12, 0x12, 0x12, 0x12 };
const u32_ptr = @ptrCast(*const u32, &bytes);
const u32_ptr: *const u32 = @ptrCast(&bytes);
try expect(u32_ptr.* == 0x12121212);
// Even this example is contrived - there are better ways to do the above than
@ -2831,7 +2831,7 @@ test "pointer casting" {
try expect(u32_value == 0x12121212);
// And even another way, the most straightforward way to do it:
try expect(@bitCast(u32, bytes) == 0x12121212);
try expect(@as(u32, @bitCast(bytes)) == 0x12121212);
}
test "pointer child type" {
@ -2921,7 +2921,7 @@ test "pointer alignment safety" {
}
fn foo(bytes: []u8) u32 {
const slice4 = bytes[1..5];
const int_slice = std.mem.bytesAsSlice(u32, @alignCast(4, slice4));
const int_slice = std.mem.bytesAsSlice(u32, @as([]align(4) u8, @alignCast(slice4)));
return int_slice[0];
}
{#code_end#}
@ -2942,7 +2942,7 @@ const expect = std.testing.expect;
test "allowzero" {
var zero: usize = 0;
var ptr = @ptrFromInt(*allowzero i32, zero);
var ptr: *allowzero i32 = @ptrFromInt(zero);
try expect(@intFromPtr(ptr) == 0);
}
{#code_end#}
@ -3354,12 +3354,12 @@ fn doTheTest() !void {
try expect(@sizeOf(Full) == 2);
try expect(@sizeOf(Divided) == 2);
var full = Full{ .number = 0x1234 };
var divided = @bitCast(Divided, full);
var divided: Divided = @bitCast(full);
try expect(divided.half1 == 0x34);
try expect(divided.quarter3 == 0x2);
try expect(divided.quarter4 == 0x1);
var ordered = @bitCast([2]u8, full);
var ordered: [2]u8 = @bitCast(full);
switch (native_endian) {
.Big => {
try expect(ordered[0] == 0x12);
@ -4428,7 +4428,7 @@ fn getNum(u: U) u32 {
// `u.a` or `u.b` and `tag` is `u`'s comptime-known tag value.
inline else => |num, tag| {
if (tag == .b) {
return @intFromFloat(u32, num);
return @intFromFloat(num);
}
return num;
}
@ -4714,7 +4714,7 @@ test "for basics" {
var sum2: i32 = 0;
for (items, 0..) |_, i| {
try expect(@TypeOf(i) == usize);
sum2 += @intCast(i32, i);
sum2 += @as(i32, @intCast(i));
}
try expect(sum2 == 10);
@ -6363,7 +6363,7 @@ const mem = std.mem;
test "cast *[1][*]const u8 to [*]const ?[*]const u8" {
const window_name = [1][*]const u8{"window name"};
const x: [*]const ?[*]const u8 = &window_name;
try expect(mem.eql(u8, std.mem.sliceTo(@ptrCast([*:0]const u8, x[0].?), 0), "window name"));
try expect(mem.eql(u8, std.mem.sliceTo(@as([*:0]const u8, @ptrCast(x[0].?)), 0), "window name"));
}
{#code_end#}
{#header_close#}
@ -6760,8 +6760,8 @@ fn peerTypeEmptyArrayAndSliceAndError(a: bool, slice: []u8) anyerror![]u8 {
}
test "peer type resolution: *const T and ?*T" {
const a = @ptrFromInt(*const usize, 0x123456780);
const b = @ptrFromInt(?*usize, 0x123456780);
const a: *const usize = @ptrFromInt(0x123456780);
const b: ?*usize = @ptrFromInt(0x123456780);
try expect(a == b);
try expect(b == a);
}
@ -7762,12 +7762,13 @@ test "global assembly" {
at compile time.
</p>
{#header_open|@addrSpaceCast#}
<pre>{#syntax#}@addrSpaceCast(comptime addrspace: std.builtin.AddressSpace, ptr: anytype) anytype{#endsyntax#}</pre>
<pre>{#syntax#}@addrSpaceCast(ptr: anytype) anytype{#endsyntax#}</pre>
<p>
Converts a pointer from one address space to another. Depending on the current target and
address spaces, this cast may be a no-op, a complex operation, or illegal. If the cast is
legal, then the resulting pointer points to the same memory location as the pointer operand.
It is always valid to cast a pointer between the same address spaces.
Converts a pointer from one address space to another. The new address space is inferred
based on the result type. Depending on the current target and address spaces, this cast
may be a no-op, a complex operation, or illegal. If the cast is legal, then the resulting
pointer points to the same memory location as the pointer operand. It is always valid to
cast a pointer between the same address spaces.
</p>
{#header_close#}
{#header_open|@addWithOverflow#}
@ -7777,10 +7778,10 @@ test "global assembly" {
</p>
{#header_close#}
{#header_open|@alignCast#}
<pre>{#syntax#}@alignCast(comptime alignment: u29, ptr: anytype) anytype{#endsyntax#}</pre>
<pre>{#syntax#}@alignCast(ptr: anytype) anytype{#endsyntax#}</pre>
<p>
{#syntax#}ptr{#endsyntax#} can be {#syntax#}*T{#endsyntax#}, {#syntax#}?*T{#endsyntax#}, or {#syntax#}[]T{#endsyntax#}.
It returns the same type as {#syntax#}ptr{#endsyntax#} except with the alignment adjusted to the new value.
Changes the alignment of a pointer. The alignment to use is inferred based on the result type.
</p>
<p>A {#link|pointer alignment safety check|Incorrect Pointer Alignment#} is added
to the generated code to make sure the pointer is aligned as promised.</p>
@ -7865,9 +7866,10 @@ comptime {
{#header_close#}
{#header_open|@bitCast#}
<pre>{#syntax#}@bitCast(comptime DestType: type, value: anytype) DestType{#endsyntax#}</pre>
<pre>{#syntax#}@bitCast(value: anytype) anytype{#endsyntax#}</pre>
<p>
Converts a value of one type to another type.
Converts a value of one type to another type. The return type is the
inferred result type.
</p>
<p>
Asserts that {#syntax#}@sizeOf(@TypeOf(value)) == @sizeOf(DestType){#endsyntax#}.
@ -8420,10 +8422,11 @@ test "main" {
{#header_close#}
{#header_open|@errSetCast#}
<pre>{#syntax#}@errSetCast(comptime T: DestType, value: anytype) DestType{#endsyntax#}</pre>
<pre>{#syntax#}@errSetCast(value: anytype) anytype{#endsyntax#}</pre>
<p>
Converts an error value from one error set to another error set. Attempting to convert an error
which is not in the destination error set results in safety-protected {#link|Undefined Behavior#}.
Converts an error value from one error set to another error set. The return type is the
inferred result type. Attempting to convert an error which is not in the destination error
set results in safety-protected {#link|Undefined Behavior#}.
</p>
{#header_close#}
@ -8535,17 +8538,17 @@ test "decl access by string" {
{#header_close#}
{#header_open|@floatCast#}
<pre>{#syntax#}@floatCast(comptime DestType: type, value: anytype) DestType{#endsyntax#}</pre>
<pre>{#syntax#}@floatCast(value: anytype) anytype{#endsyntax#}</pre>
<p>
Convert from one float type to another. This cast is safe, but may cause the
numeric value to lose precision.
numeric value to lose precision. The return type is the inferred result type.
</p>
{#header_close#}
{#header_open|@intFromFloat#}
<pre>{#syntax#}@intFromFloat(comptime DestType: type, float: anytype) DestType{#endsyntax#}</pre>
<pre>{#syntax#}@intFromFloat(float: anytype) anytype{#endsyntax#}</pre>
<p>
Converts the integer part of a floating point number to the destination type.
Converts the integer part of a floating point number to the inferred result type.
</p>
<p>
If the integer part of the floating point number cannot fit in the destination type,
@ -8660,16 +8663,17 @@ test "@hasDecl" {
{#header_close#}
{#header_open|@intCast#}
<pre>{#syntax#}@intCast(comptime DestType: type, int: anytype) DestType{#endsyntax#}</pre>
<pre>{#syntax#}@intCast(int: anytype) anytype{#endsyntax#}</pre>
<p>
Converts an integer to another integer while keeping the same numerical value.
The return type is the inferred result type.
Attempting to convert a number which is out of range of the destination type results in
safety-protected {#link|Undefined Behavior#}.
</p>
{#code_begin|test_err|test_intCast_builtin|cast truncated bits#}
test "integer cast panic" {
var a: u16 = 0xabcd;
var b: u8 = @intCast(u8, a);
var b: u8 = @intCast(a);
_ = b;
}
{#code_end#}
@ -8683,9 +8687,9 @@ test "integer cast panic" {
{#header_close#}
{#header_open|@enumFromInt#}
<pre>{#syntax#}@enumFromInt(comptime DestType: type, integer: anytype) DestType{#endsyntax#}</pre>
<pre>{#syntax#}@enumFromInt(integer: anytype) anytype{#endsyntax#}</pre>
<p>
Converts an integer into an {#link|enum#} value.
Converts an integer into an {#link|enum#} value. The return type is the inferred result type.
</p>
<p>
Attempting to convert an integer which represents no value in the chosen enum type invokes
@ -8711,16 +8715,18 @@ test "integer cast panic" {
{#header_close#}
{#header_open|@floatFromInt#}
<pre>{#syntax#}@floatFromInt(comptime DestType: type, int: anytype) DestType{#endsyntax#}</pre>
<pre>{#syntax#}@floatFromInt(int: anytype) anytype{#endsyntax#}</pre>
<p>
Converts an integer to the closest floating point representation. To convert the other way, use {#link|@intFromFloat#}. This cast is always safe.
Converts an integer to the closest floating point representation. The return type is the inferred result type.
To convert the other way, use {#link|@intFromFloat#}. This cast is always safe.
</p>
{#header_close#}
{#header_open|@ptrFromInt#}
<pre>{#syntax#}@ptrFromInt(comptime DestType: type, address: usize) DestType{#endsyntax#}</pre>
<pre>{#syntax#}@ptrFromInt(address: usize) anytype{#endsyntax#}</pre>
<p>
Converts an integer to a {#link|pointer|Pointers#}. To convert the other way, use {#link|@intFromPtr#}. Casting an address of 0 to a destination type
Converts an integer to a {#link|pointer|Pointers#}. The return type is the inferred result type.
To convert the other way, use {#link|@intFromPtr#}. Casting an address of 0 to a destination type
which in not {#link|optional|Optional Pointers#} and does not have the {#syntax#}allowzero{#endsyntax#} attribute will result in a
{#link|Pointer Cast Invalid Null#} panic when runtime safety checks are enabled.
</p>
@ -8924,9 +8930,9 @@ pub const PrefetchOptions = struct {
{#header_close#}
{#header_open|@ptrCast#}
<pre>{#syntax#}@ptrCast(comptime DestType: type, value: anytype) DestType{#endsyntax#}</pre>
<pre>{#syntax#}@ptrCast(value: anytype) anytype{#endsyntax#}</pre>
<p>
Converts a pointer of one type to a pointer of another type.
Converts a pointer of one type to a pointer of another type. The return type is the inferred result type.
</p>
<p>
{#link|Optional Pointers#} are allowed. Casting an optional pointer which is {#link|null#}
@ -9522,10 +9528,10 @@ fn List(comptime T: type) type {
{#header_close#}
{#header_open|@truncate#}
<pre>{#syntax#}@truncate(comptime T: type, integer: anytype) T{#endsyntax#}</pre>
<pre>{#syntax#}@truncate(integer: anytype) anytype{#endsyntax#}</pre>
<p>
This function truncates bits from an integer type, resulting in a smaller
or same-sized integer type.
or same-sized integer type. The return type is the inferred result type.
</p>
<p>
This function always truncates the significant bits of the integer, regardless
@ -9540,7 +9546,7 @@ const expect = std.testing.expect;
test "integer truncation" {
var a: u16 = 0xabcd;
var b: u8 = @truncate(u8, a);
var b: u8 = @truncate(a);
try expect(b == 0xcd);
}
{#code_end#}
@ -9838,7 +9844,7 @@ fn foo(x: []const u8) u8 {
{#code_begin|test_err|test_comptime_invalid_cast|type 'u32' cannot represent integer value '-1'#}
comptime {
var value: i32 = -1;
const unsigned = @intCast(u32, value);
const unsigned: u32 = @intCast(value);
_ = unsigned;
}
{#code_end#}
@ -9848,7 +9854,7 @@ const std = @import("std");
pub fn main() void {
var value: i32 = -1;
var unsigned = @intCast(u32, value);
var unsigned: u32 = @intCast(value);
std.debug.print("value: {}\n", .{unsigned});
}
{#code_end#}
@ -9861,7 +9867,7 @@ pub fn main() void {
{#code_begin|test_err|test_comptime_invalid_cast_truncate|type 'u8' cannot represent integer value '300'#}
comptime {
const spartan_count: u16 = 300;
const byte = @intCast(u8, spartan_count);
const byte: u8 = @intCast(spartan_count);
_ = byte;
}
{#code_end#}
@ -9871,7 +9877,7 @@ const std = @import("std");
pub fn main() void {
var spartan_count: u16 = 300;
const byte = @intCast(u8, spartan_count);
const byte: u8 = @intCast(spartan_count);
std.debug.print("value: {}\n", .{byte});
}
{#code_end#}
@ -10208,7 +10214,7 @@ const Foo = enum {
};
comptime {
const a: u2 = 3;
const b = @enumFromInt(Foo, a);
const b: Foo = @enumFromInt(a);
_ = b;
}
{#code_end#}
@ -10224,7 +10230,7 @@ const Foo = enum {
pub fn main() void {
var a: u2 = 3;
var b = @enumFromInt(Foo, a);
var b: Foo = @enumFromInt(a);
std.debug.print("value: {s}\n", .{@tagName(b)});
}
{#code_end#}
@ -10242,7 +10248,7 @@ const Set2 = error{
C,
};
comptime {
_ = @errSetCast(Set2, Set1.B);
_ = @as(Set2, @errSetCast(Set1.B));
}
{#code_end#}
<p>At runtime:</p>
@ -10261,7 +10267,7 @@ pub fn main() void {
foo(Set1.B);
}
fn foo(set1: Set1) void {
const x = @errSetCast(Set2, set1);
const x = @as(Set2, @errSetCast(set1));
std.debug.print("value: {}\n", .{x});
}
{#code_end#}
@ -10271,8 +10277,8 @@ fn foo(set1: Set1) void {
<p>At compile-time:</p>
{#code_begin|test_err|test_comptime_incorrect_pointer_alignment|pointer address 0x1 is not aligned to 4 bytes#}
comptime {
const ptr = @ptrFromInt(*align(1) i32, 0x1);
const aligned = @alignCast(4, ptr);
const ptr: *align(1) i32 = @ptrFromInt(0x1);
const aligned: *align(4) i32 = @alignCast(ptr);
_ = aligned;
}
{#code_end#}
@ -10286,7 +10292,7 @@ pub fn main() !void {
}
fn foo(bytes: []u8) u32 {
const slice4 = bytes[1..5];
const int_slice = mem.bytesAsSlice(u32, @alignCast(4, slice4));
const int_slice = mem.bytesAsSlice(u32, @as([]align(4) u8, @alignCast(slice4)));
return int_slice[0];
}
{#code_end#}
@ -10387,7 +10393,7 @@ fn bar(f: *Foo) void {
{#code_begin|test_err|test_comptime_invalid_null_pointer_cast|null pointer casted to type#}
comptime {
const opt_ptr: ?*i32 = null;
const ptr = @ptrCast(*i32, opt_ptr);
const ptr: *i32 = @ptrCast(opt_ptr);
_ = ptr;
}
{#code_end#}
@ -10395,7 +10401,7 @@ comptime {
{#code_begin|exe_err|runtime_invalid_null_pointer_cast#}
pub fn main() void {
var opt_ptr: ?*i32 = null;
var ptr = @ptrCast(*i32, opt_ptr);
var ptr: *i32 = @ptrCast(opt_ptr);
_ = ptr;
}
{#code_end#}