fix no default feature errors

src/iter.rs

@@ -146,7 +146,7 @@ impl<'a> Iterator for Utf16Chars<'a> {
 impl<'a> FusedIterator for Utf16Chars<'a> {}
 
 impl<'a> core::fmt::Debug for Utf16Chars<'a> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         crate::debug_fmt_utf16_iter(self.clone(), f)
     }
 }
@@ -191,7 +191,7 @@ impl<'a> Iterator for Utf32Chars<'a> {
 impl<'a> FusedIterator for Utf32Chars<'a> {}
 
 impl<'a> core::fmt::Debug for Utf32Chars<'a> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         crate::debug_fmt_utf32_iter(self.clone(), f)
     }
 }
@@ -268,7 +268,7 @@ impl<'a> Iterator for CharsLossy<'a> {
 impl<'a> FusedIterator for CharsLossy<'a> {}
 
 impl<'a> core::fmt::Debug for CharsLossy<'a> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         f.write_char('"')?;
         for c in self.clone() {
             f.write_char(c)?;

src/lib.rs

@@ -214,12 +214,15 @@ use core::{char::DecodeUtf16Error, fmt::Write};
 pub mod error;
 pub mod iter;
 #[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 mod platform;
 pub mod ucstr;
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 pub mod ucstring;
 pub mod ustr;
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 pub mod ustring;
 
 #[doc(no_inline)]
@@ -228,9 +231,11 @@ pub mod ustring;
 pub use error::{ContainsNul, FromUtf32Error, MissingNulError, MissingNulTerminator, NulError};
 pub use ucstr::{U16CStr, U32CStr, UCStr, WideCStr};
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 pub use ucstring::{U16CString, U32CString, UCString, WideCString};
 pub use ustr::{U16Str, U32Str, UStr, WideStr};
 #[cfg(feature = "alloc")]
+#[cfg_attr(docsrs, doc(cfg(feature = "alloc")))]
 pub use ustring::{U16String, U32String, UString, WideString};
 
 /// Marker trait for primitive types used to represent wide character data. Should not be used
@@ -434,16 +439,19 @@ fn debug_fmt_utf32_iter(
     fmt.write_char('"')
 }
 
+#[cfg(feature = "alloc")]
 #[inline(always)]
 fn is_utf16_surrogate(u: u16) -> bool {
     (0xD800..=0xDFFF).contains(&u)
 }
 
+#[cfg(feature = "alloc")]
 #[inline(always)]
 fn is_utf16_high_surrogate(u: u16) -> bool {
     (0xD800..=0xDBFF).contains(&u)
 }
 
+#[cfg(feature = "alloc")]
 #[inline(always)]
 fn is_utf16_low_surrogate(u: u16) -> bool {
     (0xDC00..=0xDFFF).contains(&u)

src/ucstr.rs

@@ -1454,7 +1454,7 @@ impl<C: UChar> PartialEq<crate::UStr<C>> for UCStr<C> {
 
 impl<C: UChar> PartialOrd<crate::UStr<C>> for UCStr<C> {
     #[inline]
-    fn partial_cmp(&self, other: &crate::UStr<C>) -> Option<std::cmp::Ordering> {
+    fn partial_cmp(&self, other: &crate::UStr<C>) -> Option<core::cmp::Ordering> {
         self.as_ustr().partial_cmp(other)
     }
 }

src/ustr.rs

@@ -821,7 +821,7 @@ impl<C: UChar> PartialEq<crate::UCStr<C>> for UStr<C> {
 
 impl<C: UChar> PartialOrd<crate::UCStr<C>> for UStr<C> {
     #[inline]
-    fn partial_cmp(&self, other: &crate::UCStr<C>) -> Option<std::cmp::Ordering> {
+    fn partial_cmp(&self, other: &crate::UCStr<C>) -> Option<core::cmp::Ordering> {
         self.partial_cmp(other.as_ustr())
     }
 }

src/ustring.rs

@@ -1384,13 +1384,13 @@ impl<C: UChar> ToOwned for UStr<C> {
 
 impl Write for U16String {
     #[inline]
-    fn write_str(&mut self, s: &str) -> std::fmt::Result {
+    fn write_str(&mut self, s: &str) -> core::fmt::Result {
         self.push_str(s);
         Ok(())
     }
 
     #[inline]
-    fn write_char(&mut self, c: char) -> std::fmt::Result {
+    fn write_char(&mut self, c: char) -> core::fmt::Result {
         self.push_char(c);
         Ok(())
     }