Merge pull request #300 from GreasySlug/fix/multi-line-comment

Fixed infinite loop if `#[` is more than `]#`

compiler/erg_parser/lex.rs

@@ -316,9 +316,7 @@ impl Lexer /*<'a>*/ {
     fn lex_multi_line_comment(&mut self) -> LexResult<()> {
         let mut s = "".to_string();
         let mut nest_level = 0;
-        loop {
-            match self.peek_cur_ch() {
-                Some(c) => {
+        while let Some(c) = self.peek_cur_ch() {
             if let Some(next_c) = self.peek_next_ch() {
                 match (c, next_c) {
                     ('#', '[') => nest_level += 1,
@@ -333,10 +331,12 @@ impl Lexer /*<'a>*/ {
                 if c == '\n' {
                     self.lineno_token_starts += 1;
                     self.col_token_starts = 0;
+                    s.clear();
+                    self.consume();
+                    continue;
                 }
-                        s.push(self.consume().unwrap());
             }
-                    if Self::is_bidi(self.peek_cur_ch().unwrap()) {
+            if Self::is_bidi(c) {
                 let comment = self.emit_token(Illegal, &s);
                 return Err(LexError::syntax_error(
                     line!() as usize,
@@ -350,23 +350,26 @@ impl Lexer /*<'a>*/ {
                     None,
                 ));
             }
+            s.push(self.consume().unwrap());
         }
-                None => {
         let comment = self.emit_token(Illegal, &s);
-                    return Err(LexError::syntax_error(
+        let hint = switch_lang!(
+            "japanese" => format!("`]#`の数があと{}個必要です", nest_level),
+            "simplified_chinese" => format!("需要{}个`]#`", nest_level),
+            "traditional_chinese" => format!("需要{}個`]#`", nest_level),
+            "english" => format!("{} `]#`(s) are needed", nest_level),
+        );
+        Err(LexError::syntax_error(
             line!() as usize,
             comment.loc(),
             switch_lang!(
             "japanese" => "複数行コメントが]#で閉じられていません",
             "simplified_chinese" => "未用]#号结束的多处评论",
             "traditional_chinese" => "多條評論未用]#關閉",
-                        "english" => "Multi-comment is not closed with ]#",
+            "english" => "multi-comment is not closed with ]#",
             ),
-                        None,
-                    ));
-                }
-            }
-        }
+            Some(hint),
+        ))
     }
 
     fn lex_space_indent_dedent(&mut self) -> Option<LexResult<Token>> {

tests/should_err/multi_line_invalid_nest.er

@@ -0,0 +1,10 @@
+#[
+    #[
+        #[
+            #[
+                #[
+
+                ]
+            ]
+    ]#
+]#

tests/test.rs

@@ -209,3 +209,8 @@ fn exec_subtyping() -> Result<(), ()> {
 fn exec_callable() -> Result<(), ()> {
     expect_failure("tests/should_err/callable.er", 4)
 }
+
+#[test]
+fn exec_multiline_invalid_next() -> Result<(), ()> {
+    expect_failure("tests/should_err/multi_line_invalid_nest.er", 1)
+}