Multiline strings are not accepted in define

[Lysxia]

The docs say they should work. Minimal example:

#define x \
"a
"

Error: File "w.cppo", line 2, characters 2-3
Error: Unterminated string literal

[liyishuai]

First appearance of the documentation was in 2011:

cppo/README

Lines 264 to 273 in 6ce5f43

	Comments and string literals constitute single tokens even when they
	span across multiple lines. Therefore newlines within string literals
	and comments should remain as-is (no preceding backslash) even in a
	macro body:
	#define welcome \
	"**********
	*Welcome!*
	**********
	"

However, the test suite for the same version requires backslash:

cppo/test.cppo

Lines 46 to 51 in 6ce5f43

	#define test_multiline \
	"abc\
	def" \
	(* 123 \
	456 *)
	test_multiline

Actually, backslash was required since the test suite was first written in 2009:

cppo/test.cppo

Lines 39 to 44 in 433bf21

	#define test_esc \
	"abc\
	def" \
	(* 123 \
	456 *)
	test_esc

I'd read the documentation as outdated. @mjambon Could you confirm my understanding?

[mjambon]

It's likely that I wasn't careful about this issue when I wrote the code and the documentation at the time. My inclination today is indeed to allow and preserve all "lexical elements" as they exist in OCaml (string literals, comments, ...). This means multiline strings should use the same syntax as in OCaml. If a backslash is present at the end of a line within a string literal, it should not be removed by cppo. e.g.:

#define x "hello \
  world"
x

will be turned by cppo into

"hello \
  world"

not

"hello 
  world"

also not

"hello   world"