Infinite recursion on specific grammar rules about mpc HOT 10 CLOSED

charsep      : "'" ;
strsep       : '"' ;

int          : /-?[0-9]+/ ;
char         : <charsep> (<specchar> | /[^']/) <charsep> ;
specchar     : /\\[ntr0']/ ;
string       : <strsep> /([\\]["]|[^"])*/ <strsep> ;
id           : /[a-zA-Z][a-zA-Z0-9_-?]*/ ;

mathoperator : ('+' | '-' | '*' | '/' | "mod") ;
booloperator : ('=' | "<>" | "<=" | ">=" | '<' | '>' | "and" | "or") ;

singletype   : "int" | "bool" | "char" ;
array        : <type> "[]"   ;
list         : "list" '[' <type> ']'   ;
type         : <singletype> | <list> | <array> ;

formal       : ("ref")? <type> <id> (',' <id>)* ;
header       : <type>? <id> '(' (<formal> (';' <formal>)*)? ')' ;

funcdef      : "def" <header> ':' (<funcdef> | <vardef> | <funcdecl>)* (<stmt> | <slcomment> | <mlcomment>)* "end" ;
funcdecl     : "decl" <header> ;
vardef       : <type> <id> (',' <id>)* ;

exprsimple   : <atom> | <int> | <char> | <string> | "false" | "true" | "nil" ;
expr         : "not" <expr> | "new" <type> '[' <expr> ']'
               | /nil\?/ '(' <expr> ')'
               | (<exprsimple> | '(' <expr> ')') (<mathoperator> <expr>)+
               | (<exprsimple> | '(' <expr> ')') <booloperator> <expr>
               | (<exprsimple> | '(' <expr> ')') '#' <expr>
               | ("head" | "tail") '(' <expr> ')' |  ('+' | '-') <expr>
               | <exprsimple> | '(' <expr> ')' | <id> ;

call         : <id> '(' (<expr> (',' <expr>)*)? ')' ;
atom         : <type> | (<call> | <id> | <string>) ('[' <expr> ']')+ | <call> | <id> | <string> ;
simple       : "skip" | <atom> ":=" <expr> | <call> ;
simplelist   : <simple> (',' <simple>)* ;

slcomment    : /%[^\r\n]*/ ;
mlcomment    : "<*" (<mlcomment> | /\*[^>]|[^*]/)* "*>" ;

stmt         : "return" <expr> | <simple> | "exit"
               | "if" <expr> ':' <stmt>+ ("elsif" <expr> ':' <stmt>+)* ("else" ':' <stmt>+)? "end"
               | "for" <simplelist> ';' <expr> ';' <simplelist> ':' <stmt>+ "end" ;

program      : /^/ <mlcomment>* <funcdef> <mlcomment>* /$/ ;

singletype   : "int" | "bool" | "char" ;
array        : <type> "[]"   ;
list         : "list" '[' <type> ']'   ;
type         : <singletype> | <list> | <array> ;

program      : <type>;

array        : <type> "[]"    ;
list         : "list" '[' <type> ']'   ;
type         : <singletype> | <list> | <array> ;

list         : "list" '[' <type> ']'   ;
type         : (<singletype> | <list> | <array>) "[]"* ;