-@c Copyright (C) 1999-2018 Free Software Foundation, Inc.
+@c Copyright (C) 1999-2024 Free Software Foundation, Inc.
@c This is part of the CPP and GCC manuals.
@c For copying conditions, see the file gcc.texi.
@c If this file is included with the flag ``cppmanual'' set, it is
@c formatted for inclusion in the CPP manual; otherwise the main GCC manual.
-@item -Wcomment
-@itemx -Wcomments
@opindex Wcomment
@opindex Wcomments
+@item -Wcomment
+@itemx -Wcomments
Warn whenever a comment-start sequence @samp{/*} appears in a @samp{/*}
comment, or whenever a backslash-newline appears in a @samp{//} comment.
This warning is enabled by @option{-Wall}.
-@item -Wtrigraphs
@opindex Wtrigraphs
+@item -Wtrigraphs
@anchor{Wtrigraphs}
Warn if any trigraphs are encountered that might change the meaning of
the program. Trigraphs within comments are not warned about,
get trigraph conversion without warnings, but get the other
@option{-Wall} warnings, use @samp{-trigraphs -Wall -Wno-trigraphs}.
-@item -Wundef
@opindex Wundef
@opindex Wno-undef
+@item -Wundef
Warn if an undefined identifier is evaluated in an @code{#if} directive.
Such identifiers are replaced with zero.
-@item -Wexpansion-to-defined
@opindex Wexpansion-to-defined
+@item -Wexpansion-to-defined
Warn whenever @samp{defined} is encountered in the expansion of a macro
(including the case where the macro is expanded by an @samp{#if} directive).
Such usage is not portable.
This warning is also enabled by @option{-Wpedantic} and @option{-Wextra}.
-@item -Wunused-macros
@opindex Wunused-macros
+@item -Wunused-macros
Warn about macros defined in the main file that are unused. A macro
is @dfn{used} if it is expanded or tested for existence at least once.
The preprocessor also warns if the macro has not been used at the
#endif
@end smallexample
-@item -Wno-endif-labels
@opindex Wno-endif-labels
@opindex Wendif-labels
+@item -Wno-endif-labels
Do not warn whenever an @code{#else} or an @code{#endif} are followed by text.
This sometimes happens in older programs with code of the form