diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs index e1b7b46a1ed2f..6abab050666e5 100644 --- a/library/core/src/fmt/mod.rs +++ b/library/core/src/fmt/mod.rs @@ -201,14 +201,22 @@ pub trait Write { impl SpecWriteFmt for &mut W { #[inline] default fn spec_write_fmt(mut self, args: Arguments<'_>) -> Result { - write(&mut self, args) + if let Some(s) = args.as_str() { + self.write_str(s) + } else { + write(&mut self, args) + } } } impl SpecWriteFmt for &mut W { #[inline] fn spec_write_fmt(self, args: Arguments<'_>) -> Result { - write(self, args) + if let Some(s) = args.as_str() { + self.write_str(s) + } else { + write(&mut self, args) + } } } @@ -1582,8 +1590,13 @@ impl<'a> Formatter<'a> { /// assert_eq!(format!("{:0>8}", Foo(2)), "Foo 2"); /// ``` #[stable(feature = "rust1", since = "1.0.0")] + #[inline] pub fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result { - write(self.buf, fmt) + if let Some(s) = fmt.as_str() { + self.buf.write_str(s) + } else { + write(self.buf, fmt) + } } /// Flags for formatting @@ -2272,8 +2285,13 @@ impl Write for Formatter<'_> { self.buf.write_char(c) } + #[inline] fn write_fmt(&mut self, args: Arguments<'_>) -> Result { - write(self.buf, args) + if let Some(s) = args.as_str() { + self.buf.write_str(s) + } else { + write(self.buf, args) + } } }