Replace String with InputString in ParseIntError

Currently the `ParseIntError` contains an owned copy of the input
string, this is causing us to have to use `alloc` everywhere.

We already have a alloc-friendly string replacement type, the
`InputString` - use it.

units/src/locktime/absolute.rs

@@ -6,7 +6,7 @@
 use alloc::{boxed::Box, string::String};
 use core::fmt;
 
-use internals::write_err;
+use internals::error::InputString;
 
 use crate::parse::ParseIntError;
 #[cfg(feature = "alloc")]
@@ -221,7 +221,7 @@ impl From<ParseError> for ParseTimeError {
 fn parser<T, E, S, F>(f: F) -> impl FnOnce(S) -> Result<T, E>
 where
     E: From<ParseError>,
-    S: AsRef<str> + Into<String>,
+    S: AsRef<str> + Into<InputString>,
     F: FnOnce(u32) -> Result<T, ConversionError>,
 {
     move |s| {
@@ -234,7 +234,7 @@ where
 fn parse_hex<T, E, S, F>(s: S, f: F) -> Result<T, E>
 where
     E: From<ParseError>,
-    S: AsRef<str> + Into<String>,
+    S: AsRef<str> + Into<InputString>,
     F: FnOnce(u32) -> Result<T, ConversionError>,
 {
     let n = i64::from_str_radix(parse::hex_remove_optional_prefix(s.as_ref()), 16)
@@ -310,7 +310,7 @@ enum ParseError {
 internals::impl_from_infallible!(ParseError);
 
 impl ParseError {
-    fn invalid_int<S: Into<String>>(s: S) -> impl FnOnce(core::num::ParseIntError) -> Self {
+    fn invalid_int<S: Into<InputString>>(s: S) -> impl FnOnce(core::num::ParseIntError) -> Self {
         move |source| Self::ParseInt(ParseIntError { input: s.into(), bits: 32, is_signed: true , source })
     }
 
@@ -327,13 +327,15 @@ impl ParseError {
 
         match self {
             ParseInt(ParseIntError { input, bits: _, is_signed: _, source }) if *source.kind() == IntErrorKind::PosOverflow => {
-                write!(f, "{} {} is above limit {}", subject, input, upper_bound)
+                // Outputs "failed to parse <input_string> as absolute Height/Time (<subject> is above limit <upper_bound>)"
+                write!(f, "{} ({} is above limit {})", input.display_cannot_parse("absolute Height/Time"), subject, upper_bound)
             }
             ParseInt(ParseIntError { input, bits: _, is_signed: _, source }) if *source.kind() == IntErrorKind::NegOverflow => {
-                write!(f, "{} {} is below limit {}", subject, input, lower_bound)
+                // Outputs "failed to parse <input_string> as absolute Height/Time (<subject> is below limit <lower_bound>)"
+                write!(f, "{} ({} is below limit {})", input.display_cannot_parse("absolute Height/Time"), subject, lower_bound)
             }
-            ParseInt(ParseIntError { input, bits: _, is_signed: _, source }) => {
-                write_err!(f, "failed to parse {} as {}", input, subject; source)
+            ParseInt(ParseIntError { input, bits: _, is_signed: _, source: _ }) => {
+                write!(f, "{} ({})", input.display_cannot_parse("absolute Height/Time"), subject)
             }
             Conversion(value) if *value < i64::from(lower_bound) => {
                 write!(f, "{} {} is below limit {}", subject, value, lower_bound)

units/src/parse.rs

@@ -7,6 +7,7 @@ use core::fmt;
 use core::str::FromStr;
 
 use internals::write_err;
+use internals::error::InputString;
 
 /// Error with rich context returned when a string can't be parsed as an integer.
 ///
@@ -20,7 +21,7 @@ use internals::write_err;
 #[derive(Debug, Clone, PartialEq, Eq)]
 #[non_exhaustive]
 pub struct ParseIntError {
-    pub(crate) input: String,
+    pub(crate) input: InputString,
     // for displaying - see Display impl with nice error message below
     pub(crate) bits: u8,
     // We could represent this as a single bit but it wouldn't actually derease the cost of moving
@@ -30,16 +31,10 @@ pub struct ParseIntError {
     pub(crate) source: core::num::ParseIntError,
 }
 
-impl ParseIntError {
-    /// Returns the input that was attempted to be parsed.
-    pub fn input(&self) -> &str { &self.input }
-}
-
 impl fmt::Display for ParseIntError {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let signed = if self.is_signed { "signed" } else { "unsigned" };
-        let n = if self.bits == 8 { "n" } else { "" };
-        write_err!(f, "failed to parse '{}' as a{} {}-bit {} integer", self.input, n, self.bits, signed; self.source)
+        write_err!(f, "{} ({}, {}-bit)", self.input.display_cannot_parse("integer"), signed, self.bits; self.source)
     }
 }
 
@@ -74,7 +69,7 @@ impl_integer!(u8, i8, u16, i16, u32, i32, u64, i64, u128, i128);
 ///
 /// If the caller owns `String` or `Box<str>` which is not used later it's better to pass it as
 /// owned since it avoids allocation in error case.
-pub fn int<T: Integer, S: AsRef<str> + Into<String>>(s: S) -> Result<T, ParseIntError> {
+pub fn int<T: Integer, S: AsRef<str> + Into<InputString>>(s: S) -> Result<T, ParseIntError> {
     s.as_ref().parse().map_err(|error| {
         ParseIntError {
             input: s.into(),