http://gcc.gnu.org/onlinedocs/gcc-4.2.1/gcc/Warning-Options.html#Warning-Options-Wtrigraphs
-Wtrigraphs
Warn if any trigraphs are encountered that might change the meaning of the
program (trigraphs within comments are not warned about). This warning is
enabled by -Wall.
Right now, trigraphs in // comments are not warned about. Trigraphs in /* */
comments are warned about, but should not be. Trigraphs in #if 0 ... #endif
are also warned about, but it would probably be too sticky to change that
behavior.
Example:
[EMAIL PROTECTED]:~/exp-trigraph$ cat z1.cc
#if 0
??-??-
#endif
/*
??-??-
*/
// ??-??-
[EMAIL PROTECTED]:~/exp-trigraph$ /home/mec/gcc-4.2.1/install/bin/g++ -E z1.cc
# 1 "z1.cc"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "z1.cc"
z1.cc:2:1: warning: trigraph ??- ignored, use -trigraphs to enable
z1.cc:2:4: warning: trigraph ??- ignored, use -trigraphs to enable
[EMAIL PROTECTED]:~/exp-trigraph$ /home/mec/gcc-4.3-20070810/install/bin/g++ -E
z1.cc
# 1 "z1.cc"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "z1.cc"
z1.cc:2:1: warning: trigraph ??- ignored, use -trigraphs to enable
z1.cc:2:4: warning: trigraph ??- ignored, use -trigraphs to enable
--
Summary: preprocess should ignore trigraphs in /* */ comments
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: preprocessor
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: mec at google dot com
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33143
