constify parts of libcore.

Author: Centril

src/libcore/alloc.rs

@@ -25,7 +25,7 @@ use num::NonZeroUsize;
 #[derive(Debug)]
 pub struct Excess(pub NonNull<u8>, pub usize);
 
-fn size_align<T>() -> (usize, usize) {
+const fn size_align<T>() -> (usize, usize) {
     (mem::size_of::<T>(), mem::align_of::<T>())
 }
 
@@ -116,7 +116,7 @@ impl Layout {
     /// The minimum size in bytes for a memory block of this layout.
     #[stable(feature = "alloc_layout", since = "1.28.0")]
     #[inline]
-    pub fn size(&self) -> usize { self.size_ }
+    pub const fn size(&self) -> usize { self.size_ }
 
     /// The minimum byte alignment for a memory block of this layout.
     #[stable(feature = "alloc_layout", since = "1.28.0")]

src/libcore/array.rs

@@ -77,7 +77,7 @@ impl TryFromSliceError {
            issue = "0")]
     #[inline]
     #[doc(hidden)]
-    pub fn __description(&self) -> &str {
+    pub const fn __description(&self) -> &str {
         "could not convert slice to array"
     }
 }

src/libcore/benches/iter.rs

@@ -39,7 +39,7 @@ fn bench_multiple_take(b: &mut Bencher) {
     });
 }
 
-fn scatter(x: i32) -> i32 { (x * 31) % 127 }
+const fn scatter(x: i32) -> i32 { (x * 31) % 127 }
 
 #[bench]
 fn bench_max_by_key(b: &mut Bencher) {

src/libcore/cell.rs

@@ -474,7 +474,7 @@ impl<T: ?Sized> Cell<T> {
     /// ```
     #[inline]
     #[stable(feature = "cell_as_ptr", since = "1.12.0")]
-    pub fn as_ptr(&self) -> *mut T {
+    pub const fn as_ptr(&self) -> *mut T {
         self.value.get()
     }
 
@@ -636,12 +636,12 @@ type BorrowFlag = isize;
 const UNUSED: BorrowFlag = 0;
 
 #[inline(always)]
-fn is_writing(x: BorrowFlag) -> bool {
+const fn is_writing(x: BorrowFlag) -> bool {
     x < UNUSED
 }
 
 #[inline(always)]
-fn is_reading(x: BorrowFlag) -> bool {
+const fn is_reading(x: BorrowFlag) -> bool {
     x > UNUSED
 }
 
@@ -1508,7 +1508,7 @@ impl<T: ?Sized> UnsafeCell<T> {
     /// ```
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn get(&self) -> *mut T {
+    pub const fn get(&self) -> *mut T {
         &self.value as *const T as *mut T
     }
 }

src/libcore/char/decode.rs

@@ -130,7 +130,7 @@ impl<I: Iterator<Item = u16>> Iterator for DecodeUtf16<I> {
 impl DecodeUtf16Error {
     /// Returns the unpaired surrogate which caused this error.
     #[stable(feature = "decode_utf16", since = "1.9.0")]
-    pub fn unpaired_surrogate(&self) -> u16 {
+    pub const fn unpaired_surrogate(&self) -> u16 {
         self.code
     }
 }

src/libcore/char/methods.rs

@@ -903,7 +903,7 @@ impl char {
     /// ```
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
-    pub fn is_ascii(&self) -> bool {
+    pub const fn is_ascii(&self) -> bool {
         *self as u32 <= 0x7F
     }
 

src/libcore/convert.rs

@@ -104,7 +104,6 @@
 /// assert_eq!(vec![1, 3], filtered);
 /// ```
 #[unstable(feature = "convert_id", issue = "53500")]
-#[rustc_const_unstable(feature = "const_convert_id")]
 #[inline]
 pub const fn identity<T>(x: T) -> T { x }
 

src/libcore/fmt/mod.rs

@@ -341,7 +341,7 @@ impl<'a> Arguments<'a> {
     #[doc(hidden)] #[inline]
     #[unstable(feature = "fmt_internals", reason = "internal to format_args!",
                issue = "0")]
-    pub fn new_v1(pieces: &'a [&'a str],
+    pub const fn new_v1(pieces: &'a [&'a str],
                   args: &'a [ArgumentV1<'a>]) -> Arguments<'a> {
         Arguments {
             pieces,
@@ -359,7 +359,7 @@ impl<'a> Arguments<'a> {
     #[doc(hidden)] #[inline]
     #[unstable(feature = "fmt_internals", reason = "internal to format_args!",
                issue = "0")]
-    pub fn new_v1_formatted(pieces: &'a [&'a str],
+    pub const fn new_v1_formatted(pieces: &'a [&'a str],
                             args: &'a [ArgumentV1<'a>],
                             fmt: &'a [rt::v1::Argument]) -> Arguments<'a> {
         Arguments {
@@ -1492,7 +1492,7 @@ impl<'a> Formatter<'a> {
     /// assert_eq!(&format!("{:t>6}", Foo), "tttttt");
     /// ```
     #[stable(feature = "fmt_flags", since = "1.5.0")]
-    pub fn fill(&self) -> char { self.fill }
+    pub const fn fill(&self) -> char { self.fill }
 
     /// Flag indicating what form of alignment was requested.
     ///
@@ -1562,7 +1562,7 @@ impl<'a> Formatter<'a> {
     /// assert_eq!(&format!("{}", Foo(23)), "Foo(23)");
     /// ```
     #[stable(feature = "fmt_flags", since = "1.5.0")]
-    pub fn width(&self) -> Option<usize> { self.width }
+    pub const fn width(&self) -> Option<usize> { self.width }
 
     /// Optionally specified precision for numeric types.
     ///
@@ -1589,7 +1589,7 @@ impl<'a> Formatter<'a> {
     /// assert_eq!(&format!("{}", Foo(23.2)), "Foo(23.20)");
     /// ```
     #[stable(feature = "fmt_flags", since = "1.5.0")]
-    pub fn precision(&self) -> Option<usize> { self.precision }
+    pub const fn precision(&self) -> Option<usize> { self.precision }
 
     /// Determines if the `+` flag was specified.
     ///
@@ -1617,7 +1617,9 @@ impl<'a> Formatter<'a> {
     /// assert_eq!(&format!("{}", Foo(23)), "Foo(23)");
     /// ```
     #[stable(feature = "fmt_flags", since = "1.5.0")]
-    pub fn sign_plus(&self) -> bool { self.flags & (1 << FlagV1::SignPlus as u32) != 0 }
+    pub const fn sign_plus(&self) -> bool {
+        self.flags & (1 << FlagV1::SignPlus as u32) != 0
+    }
 
     /// Determines if the `-` flag was specified.
     ///
@@ -1643,7 +1645,9 @@ impl<'a> Formatter<'a> {
     /// assert_eq!(&format!("{}", Foo(23)), "Foo(23)");
     /// ```
     #[stable(feature = "fmt_flags", since = "1.5.0")]
-    pub fn sign_minus(&self) -> bool { self.flags & (1 << FlagV1::SignMinus as u32) != 0 }
+    pub const fn sign_minus(&self) -> bool {
+        self.flags & (1 << FlagV1::SignMinus as u32) != 0
+    }
 
     /// Determines if the `#` flag was specified.
     ///
@@ -1668,7 +1672,9 @@ impl<'a> Formatter<'a> {
     /// assert_eq!(&format!("{}", Foo(23)), "23");
     /// ```
     #[stable(feature = "fmt_flags", since = "1.5.0")]
-    pub fn alternate(&self) -> bool { self.flags & (1 << FlagV1::Alternate as u32) != 0 }
+    pub const fn alternate(&self) -> bool {
+        self.flags & (1 << FlagV1::Alternate as u32) != 0
+    }
 
     /// Determines if the `0` flag was specified.
     ///
@@ -1691,15 +1697,19 @@ impl<'a> Formatter<'a> {
     /// assert_eq!(&format!("{:04}", Foo(23)), "23");
     /// ```
     #[stable(feature = "fmt_flags", since = "1.5.0")]
-    pub fn sign_aware_zero_pad(&self) -> bool {
+    pub const fn sign_aware_zero_pad(&self) -> bool {
         self.flags & (1 << FlagV1::SignAwareZeroPad as u32) != 0
     }
 
     // FIXME: Decide what public API we want for these two flags.
     // https://github.com/rust-lang/rust/issues/48584
-    fn debug_lower_hex(&self) -> bool { self.flags & (1 << FlagV1::DebugLowerHex as u32) != 0 }
+    const fn debug_lower_hex(&self) -> bool {
+        self.flags & (1 << FlagV1::DebugLowerHex as u32) != 0
+    }
 
-    fn debug_upper_hex(&self) -> bool { self.flags & (1 << FlagV1::DebugUpperHex as u32) != 0 }
+    const fn debug_upper_hex(&self) -> bool {
+        self.flags & (1 << FlagV1::DebugUpperHex as u32) != 0
+    }
 
     /// Creates a [`DebugStruct`] builder designed to assist with creation of
     /// [`fmt::Debug`] implementations for structs.

src/libcore/iter/mod.rs

@@ -2658,7 +2658,7 @@ impl<I, U> FusedIterator for Flatten<I>
           I::Item: IntoIterator<IntoIter = U, Item = U::Item> {}
 
 /// Adapts an iterator by flattening it, for use in `flatten()` and `flat_map()`.
-fn flatten_compat<I, U>(iter: I) -> FlattenCompat<I, U> {
+const fn flatten_compat<I, U>(iter: I) -> FlattenCompat<I, U> {
     FlattenCompat { iter, frontiter: None, backiter: None }
 }
 

src/libcore/iter/sources.rs

@@ -283,7 +283,7 @@ impl<T> Default for Empty<T> {
 /// assert_eq!(None, nope.next());
 /// ```
 #[stable(feature = "iter_empty", since = "1.2.0")]
-pub fn empty<T>() -> Empty<T> {
+pub const fn empty<T>() -> Empty<T> {
     Empty(marker::PhantomData)
 }