Use identifiers in format!

src/api/custom_syntax.rs

@@ -258,9 +258,8 @@ impl Engine {
                     return Err(LexError::ImproperSymbol(
                         s.to_string(),
                         format!(
-                            "Improper symbol for custom syntax at position #{}: '{}'",
+                            "Improper symbol for custom syntax at position #{}: '{s}'",
                             segments.len() + 1,
-                            s
                         ),
                     )
                     .into_err(Position::NONE));
@@ -282,9 +281,8 @@ impl Engine {
                     return Err(LexError::ImproperSymbol(
                         s.to_string(),
                         format!(
-                            "Improper symbol for custom syntax at position #{}: '{}'",
+                            "Improper symbol for custom syntax at position #{}: '{s}'",
                             segments.len() + 1,
-                            s
                         ),
                     )
                     .into_err(Position::NONE));

src/api/mod.rs

@@ -181,7 +181,7 @@ impl Engine {
                 if self.disabled_symbols.is_empty()
                     || !self.disabled_symbols.contains(&*token.syntax())
                 {
-                    return Err(format!("'{}' is a reserved keyword", keyword));
+                    return Err(format!("'{keyword}' is a reserved keyword"));
                 }
             }
             // Active standard symbols cannot be made custom
@@ -189,7 +189,7 @@ impl Engine {
                 if self.disabled_symbols.is_empty()
                     || !self.disabled_symbols.contains(&*token.syntax())
                 {
-                    return Err(format!("'{}' is a reserved operator", keyword));
+                    return Err(format!("'{keyword}' is a reserved operator"));
                 }
             }
             // Active standard symbols cannot be made custom
@@ -197,7 +197,7 @@ impl Engine {
                 if self.disabled_symbols.is_empty()
                     || !self.disabled_symbols.contains(&*token.syntax()) =>
             {
-                return Err(format!("'{}' is a reserved symbol", keyword))
+                return Err(format!("'{keyword}' is a reserved symbol"))
             }
             // Disabled symbols are OK
             Some(_) => (),

src/api/register.rs

@@ -1037,7 +1037,7 @@ impl Engine {
 
         #[cfg(not(feature = "no_module"))]
         for (name, m) in &self.global_sub_modules {
-            signatures.extend(m.gen_fn_signatures().map(|f| format!("{}::{}", name, f)));
+            signatures.extend(m.gen_fn_signatures().map(|f| format!("{name}::{f}")));
         }
 
         signatures.extend(

src/api/type_names.rs

@@ -150,7 +150,7 @@ impl Engine {
             return if x == r {
                 name.into()
             } else {
-                format!("&mut {}", r).into()
+                format!("&mut {r}").into()
             };
         }