in m4's patsubst, how do I replace newlines with spaces?

Question

How can I tell m4's patsubstr to replace all newlines in a string with a space?

I've tried:

patsubst(MULTI_LINE_STR_DEFINE,`\n',` ')

and

patsubst(MULTI_LINE_STR_DEFINE,`\\n',` ')

Answer 1

patsubst(MULTI_LINE_STR_DEFINE,`
',` ')

That is, you put the newline, literally, between quotes.