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Rollup merge of #87435 - ibraheemdev:patch-4, r=JohnTitor 

fix example code for E0617

Closes #86908
This commit is contained in:
Yuki Okushi 2021-07-29 06:11:44 +09:00 committed by GitHub
parent 87c9f32dc4 00198dd902
commit 9222984636
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1 changed files with 7 additions and 4 deletions
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11
compiler/rustc_error_codes/src/error_codes/E0617.md
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@ -3,12 +3,13 @@ Attempted to pass an invalid type of variable into a variadic function.
Erroneous code example:
```compile_fail,E0617
# use std::os::raw::{c_char, c_int};
extern "C" {
fn printf(c: *const i8, ...);
fn printf(format: *const c_char, ...) -> c_int;
}
unsafe {
printf(::std::ptr::null(), 0f32);
printf("%f\n\0".as_ptr() as _, 0f32);
// error: cannot pass an `f32` to variadic function, cast to `c_double`
}
```
@ -21,10 +22,12 @@ to import from `std::os::raw`).
In this case, `c_double` has the same size as `f64` so we can use it directly:
```no_run
# use std::os::raw::{c_char, c_int};
# extern "C" {
# fn printf(c: *const i8, ...);
# fn printf(format: *const c_char, ...) -> c_int;
# }
unsafe {
printf(::std::ptr::null(), 0f64); // ok!
printf("%f\n\0".as_ptr() as _, 0f64); // ok!
}
```