perf: Reduce binary size

It looks like this has little impact on performance.

Inspired by toml-rs#580

crates/toml_edit/src/item.rs

@@ -7,7 +7,7 @@ use crate::table::TableLike;
 use crate::{Array, InlineTable, Table, Value};
 
 /// Type representing either a value, a table, an array of tables, or none.
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub enum Item {
     /// Type representing none.
     None,
@@ -316,6 +316,18 @@ impl Item {
     }
 }
 
+impl Clone for Item {
+    #[inline(never)]
+    fn clone(&self) -> Self {
+        match self {
+            Item::None => Item::None,
+            Item::Value(v) => Item::Value(v.clone()),
+            Item::Table(v) => Item::Table(v.clone()),
+            Item::ArrayOfTables(v) => Item::ArrayOfTables(v.clone()),
+        }
+    }
+}
+
 impl Default for Item {
     fn default() -> Self {
         Item::None

crates/toml_edit/src/key.rs

@@ -29,7 +29,7 @@ use crate::InternalString;
 /// For details see [toml spec](https://github.com/toml-lang/toml/#keyvalue-pair).
 ///
 /// To parse a key use `FromStr` trait implementation: `"string".parse::<Key>()`.
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub struct Key {
     key: InternalString,
     pub(crate) repr: Option<Repr>,
@@ -142,6 +142,17 @@ impl Key {
     }
 }
 
+impl Clone for Key {
+    #[inline(never)]
+    fn clone(&self) -> Self {
+        Self {
+            key: self.key.clone(),
+            repr: self.repr.clone(),
+            decor: self.decor.clone(),
+        }
+    }
+}
+
 impl std::ops::Deref for Key {
     type Target = str;
 

crates/toml_edit/src/parser/numbers.rs

@@ -211,7 +211,10 @@ pub(crate) fn float(input: &mut Input<'_>) -> PResult<f64> {
 }
 
 pub(crate) fn float_<'i>(input: &mut Input<'i>) -> PResult<&'i str> {
-    (dec_int, alt((exp, (frac, opt(exp)).map(|_| ""))))
+    (
+        dec_int,
+        alt((exp.void(), (frac.void(), opt(exp.void())).void())),
+    )
         .recognize()
         .map(|b: &[u8]| unsafe {
             from_utf8_unchecked(