Segfault on sourceCpp

[kevinushey]

Calling sourceCpp on the following file:

// [[Rcpp::export]]
//List subset_test_list(List x, CharacterVector y) {
// return x[y];
//}

causes a segfault. Seems to fail here:

(lldb) frame select 4
frame #4: 0x000000010cbda6b6 attributes.so`get_function_signature(txt=0x000000010890ac20, pos=<unavailable>) + 246 at attributes.cpp:37
 34 
 35 // skip comments
 36 while( current_line[0] == '/' ){
-> 37 current_line = CHAR(STRING_ELT(txt, ++pos)) ;
 38 }
 39 
 40 // get everything before the first '{'

from

(lldb) frame select 5
frame #5: 0x000000010cbdb736 attributes.so`parse_cpp_function(txt=<unavailable>, line=<unavailable>) + 38 at attributes.cpp:158
 155 SEXP parse_cpp_function( SEXP txt, SEXP line ){
 156 
 157 int pos = INTEGER(line)[0] ;
-> 158 std::string signature = get_function_signature( txt, pos ) ;
 159 
 160 // find last ')' and first '('
 161 std::string::size_type endParenLoc = signature.find_last_of(')');