Should $xml_find_function_calls() be friendlier for non-syntactic calls like %%(x, y)?

[MichaelChirico]

Now we would need to provide the backticked version:

writeLines("`%%`(x, y)", tmp<-tempfile())
e = get_source_expressions(tmp)

length(e$expressions[[1L]]$xml_find_function_calls("%%"))
# [1] 0
length(e$expressions[[1L]]$xml_find_function_calls("`%%`"))
# [1] 1

Should the former usage "just work" to save the user having to think through whether ` is needed?

[MichaelChirico]

All the more annoying is quoted non-syntacted usage:

getParseData(parse(text = "'%%'()"))
#   line1 col1 line2 col2 id parent     token terminal text
# 6     1    1     1    6  6      0      expr    FALSE     
# 1     1    1     1    4  1      3 STR_CONST     TRUE '%%'
# 3     1    1     1    4  3      6      expr    FALSE     
# 2     1    5     1    5  2      6       '('     TRUE    (
# 4     1    6     1    6  4      6       ')'     TRUE    )

But we don't handle this style basically at all. It should probably generate a keyword_quote_linter() hit:

lint(text = "'%%'()", linters = keyword_quote_linter())
# i No lints found.

I'll mention that under #2471.