whitespace vs. POSIX

[Eric Blake]

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POSIX is explicit that only <blank>s and <newline>s may be discarded when
collecting macro arguments (ie. space, \t, and \n).  However, I just filed
an aardvark, since GNU m4, FreeBSD [1], and heirloom-devtools (based on
OpenSolaris) [2] all use isspace() instead of isblank() to do the
filtering (ie. blanks, but also \f, \v, and \r).  For an example,

$ printf 'len(\f)
' | m4

should output 1 per a strict reading of POSIX, but outputs 0 on every
implementation I have access to.  I will wait until the Austin group makes
a ruling on my aardvark before deciding whether it is worth patching GNU
m4 to use isblank() instead of isspace() when POSIXLY_CORRECT.

[1]
http://cvsup.pt.freebsd.org/cgi-bin/cvsweb/cvsweb.cgi/src/usr.bin/m4/main.c?rev=1.26&content-type=text/x-cvsweb-markup
[2]
http://heirloom.cvs.sourceforge.net/heirloom/heirloom-devtools/m4/m4.h?revision=1.1&view=markup

- --
Life is short - so eat dessert first!

Eric Blake             address@hidden
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