Rollup merge of #131706 - GKFX:fix-const-hacks, r=tgross35

Fix two const-hacks

Fix two pieces of code marked `FIXME(const-hack)` related to const_option #67441.

library/core/src/time.rs

@@ -213,11 +213,9 @@ impl Duration {
             // SAFETY: nanos < NANOS_PER_SEC, therefore nanos is within the valid range
             Duration { secs, nanos: unsafe { Nanoseconds(nanos) } }
         } else {
-            // FIXME(const-hack): use `.expect` once that is possible.
-            let secs = match secs.checked_add((nanos / NANOS_PER_SEC) as u64) {
-                Some(secs) => secs,
-                None => panic!("overflow in Duration::new"),
-            };
+            let secs = secs
+                .checked_add((nanos / NANOS_PER_SEC) as u64)
+                .expect("overflow in Duration::new");
             let nanos = nanos % NANOS_PER_SEC;
             // SAFETY: nanos % NANOS_PER_SEC < NANOS_PER_SEC, therefore nanos is within the valid range
             Duration { secs, nanos: unsafe { Nanoseconds(nanos) } }

library/std/src/sys/pal/windows/args.rs

@@ -18,17 +18,6 @@ use crate::sys_common::AsInner;
 use crate::sys_common::wstr::WStrUnits;
 use crate::{fmt, io, iter, vec};
 
-/// This is the const equivalent to `NonZero::new(n).unwrap()`
-///
-/// FIXME(const-hack): This can be removed once `Option::unwrap` is stably const.
-/// See the `const_option` feature (#67441).
-const fn non_zero_u16(n: u16) -> NonZero<u16> {
-    match NonZero::new(n) {
-        Some(n) => n,
-        None => panic!("called `unwrap` on a `None` value"),
-    }
-}
-
 pub fn args() -> Args {
     // SAFETY: `GetCommandLineW` returns a pointer to a null terminated UTF-16
     // string so it's safe for `WStrUnits` to use.
@@ -66,10 +55,10 @@ fn parse_lp_cmd_line<'a, F: Fn() -> OsString>(
     lp_cmd_line: Option<WStrUnits<'a>>,
     exe_name: F,
 ) -> Vec<OsString> {
-    const BACKSLASH: NonZero<u16> = non_zero_u16(b'\\' as u16);
-    const QUOTE: NonZero<u16> = non_zero_u16(b'"' as u16);
-    const TAB: NonZero<u16> = non_zero_u16(b'\t' as u16);
-    const SPACE: NonZero<u16> = non_zero_u16(b' ' as u16);
+    const BACKSLASH: NonZero<u16> = NonZero::new(b'\\' as u16).unwrap();
+    const QUOTE: NonZero<u16> = NonZero::new(b'"' as u16).unwrap();
+    const TAB: NonZero<u16> = NonZero::new(b'\t' as u16).unwrap();
+    const SPACE: NonZero<u16> = NonZero::new(b' ' as u16).unwrap();
 
     let mut ret_val = Vec::new();
     // If the cmd line pointer is null or it points to an empty string then