diff options
Diffstat (limited to 'gcc/doc/cpp.texi')
| -rw-r--r-- | gcc/doc/cpp.texi | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/gcc/doc/cpp.texi b/gcc/doc/cpp.texi index f5f29a6..c019adb 100644 --- a/gcc/doc/cpp.texi +++ b/gcc/doc/cpp.texi @@ -281,11 +281,11 @@ the character in the source character set that they represent, then converted to the execution character set, just like unescaped characters. +Unless the experimental @option{-fextended-identifiers} option is used, GCC does not permit the use of characters outside the ASCII range, nor -@samp{\u} and @samp{\U} escapes, in identifiers. We hope this will -change eventually, but there are problems with the standard semantics -of such ``extended identifiers'' which must be resolved through the -ISO C and C++ committees first. +@samp{\u} and @samp{\U} escapes, in identifiers. Even with that +option, characters outside the ASCII range can only be specified with +the @samp{\u} and @samp{\U} escapes, not used directly in identifiers. @node Initial processing @section Initial processing @@ -510,8 +510,10 @@ In the 1999 C standard, identifiers may contain letters which are not part of the ``basic source character set'', at the implementation's discretion (such as accented Latin letters, Greek letters, or Chinese ideograms). This may be done with an extended character set, or the -@samp{\u} and @samp{\U} escape sequences. GCC does not presently -implement either feature in the preprocessor or the compiler. +@samp{\u} and @samp{\U} escape sequences. The implementation of this +feature in GCC is experimental; such characters are only accepted in +the @samp{\u} and @samp{\U} forms and only if +@option{-fextended-identifiers} is used. As an extension, GCC treats @samp{$} as a letter. This is for compatibility with some systems, such as VMS, where @samp{$} is commonly @@ -3791,7 +3793,9 @@ character set may be controlled by the user, with the The C and C++ standards allow identifiers to be composed of @samp{_} and the alphanumeric characters. C++ and C99 also allow universal character names, and C99 further permits implementation-defined -characters. +characters. GCC currently only permits universal character names if +@option{-fextended-identifiers} is used, because the implementation of +universal character names in identifiers is experimental. GCC allows the @samp{$} character in identifiers as an extension for most targets. This is true regardless of the @option{std=} switch, |