".." doesn't make it through "clang -E" intact

[efriedma-quic]

Bugzilla Link	4008
Resolution	FIXED
Resolved on	Mar 12, 2010 00:57
Version	unspecified
OS	Linux

Extended Description

Testcase:
..

Output of "gcc -E":

1 ""

1 ""

1 ""

1 ""

..

Output of "clang -E":

1 ""

1 "" 1

1 "" 1

103 ""

103 "" 1

104 "" 2

1 "" 2

. .

This issue blocks building emacs; the emacs build system runs its makefiles through the C preprocessor. Relevant snippet:
ALL_CFLAGS = C_SWITCH_SYSTEM C_SWITCH_MACHINE -DHAVE_CONFIG_H
-I. -I../src -I${srcdir} -I${srcdir}/../src ${LDFLAGS} ${CPPFLAGS} ${CFLAGS}

[lattner]

The problem here is that paste avoidance just has the current and next token. It doesn't know that the "." and "." won't be followed by another ".". Perhaps we need a special case for ..

[efriedma-quic]

Possible patch?
Perhaps this is a little too tricky, but I can't see anything obviously wrong with it.

[lattner]

I think this will break:
#define x .
..x

[lattner]

No, you're right. This is a great solution! Applied here:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20090420/016034.html