parser: update position when reporting lexer errors for unrecognized token

By default we point to the start of the most recent token we parsed.
This is used when erroring out on parser issues, to print the line that
caused the error, with a pointer to where we were when we got the error.

In this particular case, the pointer pointed to the start of the last
token we successfully parsed (col), but was not updated if we hit a
token we didn't understand at all. Instead use a pointer to the
unrecognized token itself.

Fixes: #14415

Author: eli-schwartz

mesonbuild/mparser.py

@@ -221,7 +221,7 @@ def lex(self, filename: str) -> T.Generator[Token, None, None]:
                     yield Token(tid, filename, curline_start, curline, col, bytespan, value)
                     break
             if not matched:
-                raise ParseException(f'lexer: unrecognized token {self.code[loc]!r}', self.getline(line_start), lineno, col)
+                raise ParseException(f'lexer: unrecognized token {self.code[loc]!r}', self.getline(line_start), lineno, loc - line_start)
 
 @dataclass
 class BaseNode: