```windows-strings``` ```PCWSTR::as_wide``` return lifetime should be modifiable

[NewYearPrism]

Summary

Below fails to compile:

let p_cmdline = unsafe { GetCommandLineW() };
OsString::from_wide(unsafe { windows_strings::PCWSTR::from_raw(p_cmdline).as_wide() });

It should have no problem since the validity of returned &[u16] does not depend on PCWSTR.
Or is that on purpose out of consideration?

(Now workaround is to use core::slice::from_raw_parts by myself.

Crate manifest

windows-strings = "0.5.1"

Crate code

[NewYearPrism]

(also I could outstretch unsafe block to defer dropping

let p_cmdline = unsafe { GetCommandLineW() };
unsafe { OsString::from_wide(windows_strings::PCWSTR::from_raw(p_cmdline).as_wide()) };

[tim-weis]

Assuming that the code you're trying to compile is this

let p_cmdline = unsafe { GetCommandLineW() };
OsString::from_wide(unsafe { windows_strings::PCWSTR::from_raw(p_cmdline.0).as_wide() });

you'll get this error diagnostic:

error[E0716]: temporary value dropped while borrowed
 --> src\main.rs:7:34
  |
7 |     OsString::from_wide(unsafe { windows_strings::PCWSTR::from_raw(p_cmdline.0).as_wide() });
  |     -------------------          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^         - temporary value is freed at the end of this statement
  |     |                            |
  |     |                            creates a temporary value which is freed while still in use
  |     borrow later used by call
  |

The important bits mention a "temporary value", and the slice returned from as_wide() indeed cannot outlive the (temporary) PCWSTR used as its source. This is by design.

One solution (as you have discovered) is to extend the lifetime of the source PCWSTR. An easier solution is to avoid the creation of an intermediary altogether:

let p_cmdline = unsafe { GetCommandLineW() };
OsString::from_wide(unsafe { p_cmdline.as_wide() });

While I no longer actively contribute to Stack Overflow, questions like this are better suited for dedicated Q&A platforms (like Stack Overflow).