Commit 2b29424efd
2021-11-28 12:28:47
1 parent
8f89056Changed files (1)
doc/langref.html.in
@@ -8537,6 +8537,16 @@ test "@hasDecl" {
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|cast truncated bits#}
+test "integer cast panic" {
+ var a: u16 = 0xabcd;
+ var b: u8 = @intCast(u8, a);
+ _ = b;
+}
+ {#code_end#}
+ <p>
+ To truncate the significant bits of a number out of range of the destination type, use {#link|@truncate#}.
+ </p>
<p>
If {#syntax#}T{#endsyntax#} is {#syntax#}comptime_int{#endsyntax#},
then this is semantically equivalent to {#link|Type Coercion#}.
@@ -9380,17 +9390,11 @@ fn List(comptime T: type) type {
or same-sized integer type.
</p>
<p>
- The following produces safety-checked {#link|Undefined Behavior#}:
+ This function always truncates the significant bits of the integer, regardless
+ of endianness on the target platform.
</p>
- {#code_begin|test_err|cast truncated bits#}
-test "integer cast panic" {
- var a: u16 = 0xabcd;
- var b: u8 = @intCast(u8, a);
- _ = b;
-}
- {#code_end#}
<p>
- However this is well defined and working code:
+ Calling {#syntax#}@truncate{#endsyntax#} on a number out of range of the destination type is well defined and working code:
</p>
{#code_begin|test|truncate#}
const std = @import("std");
@@ -9403,8 +9407,7 @@ test "integer truncation" {
}
{#code_end#}
<p>
- This function always truncates the significant bits of the integer, regardless
- of endianness on the target platform.
+ Use {#link|@intCast#} to convert numbers guaranteed to fit the destination type.
</p>
{#header_close#}