https://github.com/complyue/dcp is a minimum working example to reprod this error
$ cabal run dcp:dcp < samples/basic.txt
Up to date
dcp: 10:1:
|
10 | method doXXX() pass
| ^
unexpected 'm'
expecting ';'
CallStack (from HasCallStack):
error, called at src/Parser.hs:149:14 in main:Parser
$
I believe it's optionalSemicolon causing the failure:
https://github.com/complyue/dcp/blob/1df7ad590d78d4fa9a017eb53f9f265e291bdfa7/src/Parser.hs#L50-L54
findIt = do
-- ignore leading whitespaces and an optional semicolon in between
nbsc >> optionalSemicolon >> nbsc
-- try get a doc comment block
getIt >>= \case
And it's defined like this: https://github.com/complyue/dcp/blob/1df7ad590d78d4fa9a017eb53f9f265e291bdfa7/src/Parser.hs#L31-L32
optionalSemicolon :: Parser Bool
optionalSemicolon = fromMaybe False <$> optional (True <$ symbol ";")
I can't reason about why it can fail like this.
Turns out it is because the symbol in optionalSemicolon is referencing sc while it shouldn't. Solved like this:
optionalComma :: Parser Bool
-optionalComma = fromMaybe False <$> optional (True <$ symbol ",")
+optionalComma = fromMaybe False <$> optional (True <$ string ",")
optionalSemicolon :: Parser Bool
-optionalSemicolon = fromMaybe False <$> optional (True <$ symbol ";")
+optionalSemicolon = fromMaybe False <$> optional (True <$ string ";")