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langref: explain why comptime_float cannot be divided by comptime_int

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Co-authored-by: Andrew Kelley <andrew@ziglang.org>
Co-authored-by: Veikka Tuominen <git@vexu.eu>
This commit is contained in:
Maks S
2020-06-28 17:42:37 -07:00
committed by Vexu
parent 6e0fb06010
commit 50139aa232
1 changed files with 19 additions and 3 deletions
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22
doc/langref.html.in
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@@ -248,7 +248,7 @@ pub fn main() !void {
</p>
<p>
Following the <code>hello.zig</code> Zig code sample, the {#link|Zig Build System#} is used
to build an executable program from the <code>hello.zig</code> source code. Then, the
to build an executable program from the <code>hello.zig</code> source code. Then, the
<code>hello</code> program is executed showing its output <code>Hello, world!</code>. The
lines beginning with <code>$</code> represent command line prompts and a command.
Everything else is program output.
@@ -293,7 +293,7 @@ pub fn main() !void {
<p>
In Zig, a function's block of statements and expressions are surrounded by <code>{</code> and
<code>}</code> curly-braces. Inside of the <code>main</code> function are expressions that perform
the task of outputting <code>Hello, world!</code> to standard output.
the task of outputting <code>Hello, world!</code> to standard output.
</p>
<p>
First, a constant identifier, <code>stdout</code>, is initialized to represent standard output's
@@ -5135,6 +5135,22 @@ test "float widening" {
var c: f64 = b;
var d: f128 = c;
assert(d == a);
}
{#code_end#}
{#header_close#}
{#header_open|Type Coercion: Coercion Float to Int#}
<p>
A compiler error is appropriate because this ambiguous expression leaves the compiler
two choices about the coercion.
<ul>
<li> Cast {#syntax#}54.0{#endsyntax#} to {#syntax#}comptime_int{#endsyntax#} resulting in {#syntax#}@as(comptime_int, 10){#endsyntax#}, which is casted to {#syntax#}@as(f32, 10){#endsyntax#}</li>
<li> Cast {#syntax#}5{#endsyntax#} to {#syntax#}comptime_float{#endsyntax#} resulting in {#syntax#}@as(comptime_float, 10.8){#endsyntax#}, which is casted to {#syntax#}@as(f32, 10.8){#endsyntax#}</li>
</ul>
</p>
{#code_begin|test_err#}
// Compile time coercion of float to int
test "implicit cast to comptime_int" {
var f: f32 = 54.0 / 5;
}
{#code_end#}
{#header_close#}
@@ -8179,7 +8195,7 @@ const expect = std.testing.expect;
test "@src" {
doTheTest();
}
fn doTheTest() void {
const src = @src();