Rollup merge of #64178 - mati865:clippy, r=scottmcm

More Clippy fixes for alloc, core and std

Continuation of https://github.com/rust-lang/rust/pull/63805

3 files changed, 7 insertions, 9 deletions

diff --git a/src/libcore/fmt/mod.rs b/src/libcore/fmt/mod.rs
index 8413b2e0ac4..0e83a282b18 100644
--- a/src/libcore/fmt/mod.rs
+++ b/src/libcore/fmt/mod.rs
@@ -2025,7 +2025,7 @@ impl<T: ?Sized> Pointer for *const T {
         if f.alternate() {
             f.flags |= 1 << (FlagV1::SignAwareZeroPad as u32);
 
-            if let None = f.width {
+            if f.width.is_none() {
                 f.width = Some(((mem::size_of::<usize>() * 8) / 4) + 2);
             }
         }
diff --git a/src/libcore/num/dec2flt/algorithm.rs b/src/libcore/num/dec2flt/algorithm.rs
index fa3c8075378..ed89852dc48 100644
--- a/src/libcore/num/dec2flt/algorithm.rs
+++ b/src/libcore/num/dec2flt/algorithm.rs
@@ -143,13 +143,12 @@ pub fn fast_path<T: RawFloat>(integral: &[u8], fractional: &[u8], e: i64) -> Opt
 /// > not a bound for the true error, but bounds the difference between the approximation z and
 /// > the best possible approximation that uses p bits of significand.)
 pub fn bellerophon<T: RawFloat>(f: &Big, e: i16) -> T {
-    let slop;
-    if f <= &Big::from_u64(T::MAX_SIG) {
+    let slop = if f <= &Big::from_u64(T::MAX_SIG) {
         // The cases abs(e) < log5(2^N) are in fast_path()
-        slop = if e >= 0 { 0 } else { 3 };
+        if e >= 0 { 0 } else { 3 }
     } else {
-        slop = if e >= 0 { 1 } else { 4 };
-    }
+        if e >= 0 { 1 } else { 4 }
+    };
     let z = rawfp::big_to_fp(f).mul(&power_of_ten(e)).normalize();
     let exp_p_n = 1 << (P - T::SIG_BITS as u32);
     let lowbits: i64 = (z.f % exp_p_n) as i64;
diff --git a/src/libcore/option.rs b/src/libcore/option.rs
index 9eb29eae7f7..89f2d7ab29c 100644
--- a/src/libcore/option.rs
+++ b/src/libcore/option.rs
@@ -837,9 +837,8 @@ impl<T> Option<T> {
     #[inline]
     #[stable(feature = "option_entry", since = "1.20.0")]
     pub fn get_or_insert_with<F: FnOnce() -> T>(&mut self, f: F) -> &mut T {
-        match *self {
-            None => *self = Some(f()),
-            _ => (),
+        if let None = *self {
+            *self = Some(f());
         }
 
         match *self {