Fix error when lexing ! at end-of-file (casey#2520)

src/compile_error.rs

@@ -247,13 +247,17 @@ impl Display for CompileError<'_> {
       ),
       UndefinedVariable { variable } => write!(f, "Variable `{variable}` not defined"),
       UnexpectedCharacter { expected } => {
-        write!(f, "Expected character {}", List::or_ticked(expected.iter()))
+        write!(f, "Expected character {}", List::or_ticked(expected))
       }
       UnexpectedClosingDelimiter { close } => {
         write!(f, "Unexpected closing delimiter `{}`", close.close())
       }
       UnexpectedEndOfToken { expected } => {
-        write!(f, "Expected character `{expected}` but found end-of-file")
+        write!(
+          f,
+          "Expected character `{}` but found end-of-file",
+          List::or_ticked(expected),
+        )
       }
       UnexpectedToken {
         ref expected,

src/compile_error_kind.rs

@@ -113,7 +113,7 @@ pub(crate) enum CompileErrorKind<'src> {
     close: Delimiter,
   },
   UnexpectedEndOfToken {
-    expected: char,
+    expected: Vec<char>,
   },
   UnexpectedToken {
     expected: Vec<TokenKind>,

src/lexer.rs

@@ -639,13 +639,17 @@ impl<'src> Lexer<'src> {
       // Emit an unspecified token to consume the current character,
       self.token(Unspecified);
 
+      let expected = choices.iter().map(|choice| choice.0).collect();
+
+      if self.at_eof() {
+        return Err(self.error(UnexpectedEndOfToken { expected }));
+      }
+
       // …and advance past another character,
       self.advance()?;
 
       // …so that the error we produce highlights the unexpected character.
-      return Err(self.error(UnexpectedCharacter {
-        expected: choices.iter().map(|choice| choice.0).collect(),
-      }));
+      return Err(self.error(UnexpectedCharacter { expected }));
     }
 
     Ok(())
@@ -710,7 +714,9 @@ impl<'src> Lexer<'src> {
       self.token(Unspecified);
 
       if self.at_eof() {
-        return Err(self.error(UnexpectedEndOfToken { expected: right }));
+        return Err(self.error(UnexpectedEndOfToken {
+          expected: vec![right],
+        }));
       }
 
       // …and advance past another character,
@@ -2281,9 +2287,10 @@ mod tests {
     column: 1,
     width:  0,
     kind:   UnexpectedEndOfToken {
-      expected: '&',
+      expected: vec!['&'],
     },
   }
+
   error! {
     name:   ampersand_unexpected,
     input:  "&%",
@@ -2296,6 +2303,18 @@ mod tests {
     },
   }
 
+  error! {
+    name:   bang_eof,
+    input:  "!",
+    offset: 1,
+    line:   0,
+    column: 1,
+    width:  0,
+    kind:   UnexpectedEndOfToken {
+      expected: vec!['=', '~'],
+    },
+  }
+
   #[test]
   fn presume_error() {
     let compile_error = Lexer::new("justfile".as_ref(), "!")