Invalid "\" crashes lintr

[renkun-ken]

If the source code contains any invalid use of \, then lintr::lint() will stop working:

col <- c("a", \)

The case could be simplified to the following:

> parse(text = "\\")                                                                                                        
Error in parse(text = "\\") : <text>:1:1: unexpected input
1: \
    ^
Backtrace:
1: parse(text = "\\")

> lintr::lint("\\\n")                                                                                                       
Error in read_xml.raw(charToRaw(enc2utf8(x)), "UTF-8", ..., as_html = as_html,  : 
  StartTag: invalid element name [68]
Backtrace:
1: read_xml.raw(charToRaw(enc2utf8(x)), "UTF-8", ..., as_html = as_html, 
2: read_xml.character(xmlparsedata::xml_parse_data(pc))
3: xml2::read_xml(xmlparsedata::xml_parse_data(pc))
4: FUN(X[[i]], ...)
5: lapply(X = top_level_expressions(parsed_content), FUN = get_single_source_expression, 
6: get_source_expressions(filename)
7: lintr::lint("\\\n")

Looks like it is caused by xmlparsedata writing invalid XML and lintr does not handle such case.

Before error occurs, pc got the following value:

  line1 col1 line2 col2 id parent token terminal text
1     1    1     1    1  1      0    \\    FALSE   \\

xmlparsedata::xml_parse_data(pc) produces the following XML with invalid tokens:

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<exprlist>
  <\ line1="1" col1="1" line2="1" col2="1" start="3" end="3">\
  </\>
</exprlist>