cppopts.texi revision 169690
1@c Copyright (c) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 2@c Free Software Foundation, Inc. 3@c This is part of the CPP and GCC manuals. 4@c For copying conditions, see the file gcc.texi. 5 6@c --------------------------------------------------------------------- 7@c Options affecting the preprocessor 8@c --------------------------------------------------------------------- 9 10@c If this file is included with the flag ``cppmanual'' set, it is 11@c formatted for inclusion in the CPP manual; otherwise the main GCC manual. 12 13@table @gcctabopt 14@item -D @var{name} 15@opindex D 16Predefine @var{name} as a macro, with definition @code{1}. 17 18@item -D @var{name}=@var{definition} 19The contents of @var{definition} are tokenized and processed as if 20they appeared during translation phase three in a @samp{#define} 21directive. In particular, the definition will be truncated by 22embedded newline characters. 23 24If you are invoking the preprocessor from a shell or shell-like 25program you may need to use the shell's quoting syntax to protect 26characters such as spaces that have a meaning in the shell syntax. 27 28If you wish to define a function-like macro on the command line, write 29its argument list with surrounding parentheses before the equals sign 30(if any). Parentheses are meaningful to most shells, so you will need 31to quote the option. With @command{sh} and @command{csh}, 32@option{-D'@var{name}(@var{args@dots{}})=@var{definition}'} works. 33 34@option{-D} and @option{-U} options are processed in the order they 35are given on the command line. All @option{-imacros @var{file}} and 36@option{-include @var{file}} options are processed after all 37@option{-D} and @option{-U} options. 38 39@item -U @var{name} 40@opindex U 41Cancel any previous definition of @var{name}, either built in or 42provided with a @option{-D} option. 43 44@item -undef 45@opindex undef 46Do not predefine any system-specific or GCC-specific macros. The 47standard predefined macros remain defined. 48@ifset cppmanual 49@xref{Standard Predefined Macros}. 50@end ifset 51 52@item -I @var{dir} 53@opindex I 54Add the directory @var{dir} to the list of directories to be searched 55for header files. 56@ifset cppmanual 57@xref{Search Path}. 58@end ifset 59Directories named by @option{-I} are searched before the standard 60system include directories. If the directory @var{dir} is a standard 61system include directory, the option is ignored to ensure that the 62default search order for system directories and the special treatment 63of system headers are not defeated 64@ifset cppmanual 65(@pxref{System Headers}) 66@end ifset 67. 68 69@item -o @var{file} 70@opindex o 71Write output to @var{file}. This is the same as specifying @var{file} 72as the second non-option argument to @command{cpp}. @command{gcc} has a 73different interpretation of a second non-option argument, so you must 74use @option{-o} to specify the output file. 75 76@item -Wall 77@opindex Wall 78Turns on all optional warnings which are desirable for normal code. 79At present this is @option{-Wcomment}, @option{-Wtrigraphs}, 80@option{-Wmultichar} and a warning about integer promotion causing a 81change of sign in @code{#if} expressions. Note that many of the 82preprocessor's warnings are on by default and have no options to 83control them. 84 85@item -Wcomment 86@itemx -Wcomments 87@opindex Wcomment 88@opindex Wcomments 89Warn whenever a comment-start sequence @samp{/*} appears in a @samp{/*} 90comment, or whenever a backslash-newline appears in a @samp{//} comment. 91(Both forms have the same effect.) 92 93@item -Wtrigraphs 94@opindex Wtrigraphs 95@anchor{Wtrigraphs} 96Most trigraphs in comments cannot affect the meaning of the program. 97However, a trigraph that would form an escaped newline (@samp{??/} at 98the end of a line) can, by changing where the comment begins or ends. 99Therefore, only trigraphs that would form escaped newlines produce 100warnings inside a comment. 101 102This option is implied by @option{-Wall}. If @option{-Wall} is not 103given, this option is still enabled unless trigraphs are enabled. To 104get trigraph conversion without warnings, but get the other 105@option{-Wall} warnings, use @samp{-trigraphs -Wall -Wno-trigraphs}. 106 107@item -Wtraditional 108@opindex Wtraditional 109Warn about certain constructs that behave differently in traditional and 110ISO C@. Also warn about ISO C constructs that have no traditional C 111equivalent, and problematic constructs which should be avoided. 112@ifset cppmanual 113@xref{Traditional Mode}. 114@end ifset 115 116@item -Wimport 117@opindex Wimport 118Warn the first time @samp{#import} is used. 119 120@item -Wundef 121@opindex Wundef 122Warn whenever an identifier which is not a macro is encountered in an 123@samp{#if} directive, outside of @samp{defined}. Such identifiers are 124replaced with zero. 125 126@item -Wunused-macros 127@opindex Wunused-macros 128Warn about macros defined in the main file that are unused. A macro 129is @dfn{used} if it is expanded or tested for existence at least once. 130The preprocessor will also warn if the macro has not been used at the 131time it is redefined or undefined. 132 133Built-in macros, macros defined on the command line, and macros 134defined in include files are not warned about. 135 136@emph{Note:} If a macro is actually used, but only used in skipped 137conditional blocks, then CPP will report it as unused. To avoid the 138warning in such a case, you might improve the scope of the macro's 139definition by, for example, moving it into the first skipped block. 140Alternatively, you could provide a dummy use with something like: 141 142@smallexample 143#if defined the_macro_causing_the_warning 144#endif 145@end smallexample 146 147@item -Wendif-labels 148@opindex Wendif-labels 149Warn whenever an @samp{#else} or an @samp{#endif} are followed by text. 150This usually happens in code of the form 151 152@smallexample 153#if FOO 154@dots{} 155#else FOO 156@dots{} 157#endif FOO 158@end smallexample 159 160@noindent 161The second and third @code{FOO} should be in comments, but often are not 162in older programs. This warning is on by default. 163 164@item -Werror 165@opindex Werror 166Make all warnings into hard errors. Source code which triggers warnings 167will be rejected. 168 169@item -Wsystem-headers 170@opindex Wsystem-headers 171Issue warnings for code in system headers. These are normally unhelpful 172in finding bugs in your own code, therefore suppressed. If you are 173responsible for the system library, you may want to see them. 174 175@item -w 176@opindex w 177Suppress all warnings, including those which GNU CPP issues by default. 178 179@item -pedantic 180@opindex pedantic 181Issue all the mandatory diagnostics listed in the C standard. Some of 182them are left out by default, since they trigger frequently on harmless 183code. 184 185@item -pedantic-errors 186@opindex pedantic-errors 187Issue all the mandatory diagnostics, and make all mandatory diagnostics 188into errors. This includes mandatory diagnostics that GCC issues 189without @samp{-pedantic} but treats as warnings. 190 191@item -M 192@opindex M 193@cindex make 194@cindex dependencies, make 195Instead of outputting the result of preprocessing, output a rule 196suitable for @command{make} describing the dependencies of the main 197source file. The preprocessor outputs one @command{make} rule containing 198the object file name for that source file, a colon, and the names of all 199the included files, including those coming from @option{-include} or 200@option{-imacros} command line options. 201 202Unless specified explicitly (with @option{-MT} or @option{-MQ}), the 203object file name consists of the basename of the source file with any 204suffix replaced with object file suffix. If there are many included 205files then the rule is split into several lines using @samp{\}-newline. 206The rule has no commands. 207 208This option does not suppress the preprocessor's debug output, such as 209@option{-dM}. To avoid mixing such debug output with the dependency 210rules you should explicitly specify the dependency output file with 211@option{-MF}, or use an environment variable like 212@env{DEPENDENCIES_OUTPUT} (@pxref{Environment Variables}). Debug output 213will still be sent to the regular output stream as normal. 214 215Passing @option{-M} to the driver implies @option{-E}, and suppresses 216warnings with an implicit @option{-w}. 217 218@item -MM 219@opindex MM 220Like @option{-M} but do not mention header files that are found in 221system header directories, nor header files that are included, 222directly or indirectly, from such a header. 223 224This implies that the choice of angle brackets or double quotes in an 225@samp{#include} directive does not in itself determine whether that 226header will appear in @option{-MM} dependency output. This is a 227slight change in semantics from GCC versions 3.0 and earlier. 228 229@anchor{dashMF} 230@item -MF @var{file} 231@opindex MF 232When used with @option{-M} or @option{-MM}, specifies a 233file to write the dependencies to. If no @option{-MF} switch is given 234the preprocessor sends the rules to the same place it would have sent 235preprocessed output. 236 237When used with the driver options @option{-MD} or @option{-MMD}, 238@option{-MF} overrides the default dependency output file. 239 240@item -MG 241@opindex MG 242In conjunction with an option such as @option{-M} requesting 243dependency generation, @option{-MG} assumes missing header files are 244generated files and adds them to the dependency list without raising 245an error. The dependency filename is taken directly from the 246@code{#include} directive without prepending any path. @option{-MG} 247also suppresses preprocessed output, as a missing header file renders 248this useless. 249 250This feature is used in automatic updating of makefiles. 251 252@item -MP 253@opindex MP 254This option instructs CPP to add a phony target for each dependency 255other than the main file, causing each to depend on nothing. These 256dummy rules work around errors @command{make} gives if you remove header 257files without updating the @file{Makefile} to match. 258 259This is typical output: 260 261@smallexample 262test.o: test.c test.h 263 264test.h: 265@end smallexample 266 267@item -MT @var{target} 268@opindex MT 269 270Change the target of the rule emitted by dependency generation. By 271default CPP takes the name of the main input file, including any path, 272deletes any file suffix such as @samp{.c}, and appends the platform's 273usual object suffix. The result is the target. 274 275An @option{-MT} option will set the target to be exactly the string you 276specify. If you want multiple targets, you can specify them as a single 277argument to @option{-MT}, or use multiple @option{-MT} options. 278 279For example, @option{@w{-MT '$(objpfx)foo.o'}} might give 280 281@smallexample 282$(objpfx)foo.o: foo.c 283@end smallexample 284 285@item -MQ @var{target} 286@opindex MQ 287 288Same as @option{-MT}, but it quotes any characters which are special to 289Make. @option{@w{-MQ '$(objpfx)foo.o'}} gives 290 291@smallexample 292$$(objpfx)foo.o: foo.c 293@end smallexample 294 295The default target is automatically quoted, as if it were given with 296@option{-MQ}. 297 298@item -MD 299@opindex MD 300@option{-MD} is equivalent to @option{-M -MF @var{file}}, except that 301@option{-E} is not implied. The driver determines @var{file} based on 302whether an @option{-o} option is given. If it is, the driver uses its 303argument but with a suffix of @file{.d}, otherwise it take the 304basename of the input file and applies a @file{.d} suffix. 305 306If @option{-MD} is used in conjunction with @option{-E}, any 307@option{-o} switch is understood to specify the dependency output file 308(@pxref{dashMF,,-MF}), but if used without @option{-E}, each @option{-o} 309is understood to specify a target object file. 310 311Since @option{-E} is not implied, @option{-MD} can be used to generate 312a dependency output file as a side-effect of the compilation process. 313 314@item -MMD 315@opindex MMD 316Like @option{-MD} except mention only user header files, not system 317header files. 318 319@ifclear cppmanual 320@item -fpch-deps 321@opindex fpch-deps 322When using precompiled headers (@pxref{Precompiled Headers}), this flag 323will cause the dependency-output flags to also list the files from the 324precompiled header's dependencies. If not specified only the 325precompiled header would be listed and not the files that were used to 326create it because those files are not consulted when a precompiled 327header is used. 328 329@item -fpch-preprocess 330@opindex fpch-preprocess 331This option allows use of a precompiled header (@pxref{Precompiled 332Headers}) together with @option{-E}. It inserts a special @code{#pragma}, 333@code{#pragma GCC pch_preprocess "<filename>"} in the output to mark 334the place where the precompiled header was found, and its filename. When 335@option{-fpreprocessed} is in use, GCC recognizes this @code{#pragma} and 336loads the PCH@. 337 338This option is off by default, because the resulting preprocessed output 339is only really suitable as input to GCC@. It is switched on by 340@option{-save-temps}. 341 342You should not write this @code{#pragma} in your own code, but it is 343safe to edit the filename if the PCH file is available in a different 344location. The filename may be absolute or it may be relative to GCC's 345current directory. 346 347@end ifclear 348@item -x c 349@itemx -x c++ 350@itemx -x objective-c 351@itemx -x assembler-with-cpp 352@opindex x 353Specify the source language: C, C++, Objective-C, or assembly. This has 354nothing to do with standards conformance or extensions; it merely 355selects which base syntax to expect. If you give none of these options, 356cpp will deduce the language from the extension of the source file: 357@samp{.c}, @samp{.cc}, @samp{.m}, or @samp{.S}. Some other common 358extensions for C++ and assembly are also recognized. If cpp does not 359recognize the extension, it will treat the file as C; this is the most 360generic mode. 361 362@emph{Note:} Previous versions of cpp accepted a @option{-lang} option 363which selected both the language and the standards conformance level. 364This option has been removed, because it conflicts with the @option{-l} 365option. 366 367@item -std=@var{standard} 368@itemx -ansi 369@opindex ansi 370@opindex std= 371Specify the standard to which the code should conform. Currently CPP 372knows about C and C++ standards; others may be added in the future. 373 374@var{standard} 375may be one of: 376@table @code 377@item iso9899:1990 378@itemx c89 379The ISO C standard from 1990. @samp{c89} is the customary shorthand for 380this version of the standard. 381 382The @option{-ansi} option is equivalent to @option{-std=c89}. 383 384@item iso9899:199409 385The 1990 C standard, as amended in 1994. 386 387@item iso9899:1999 388@itemx c99 389@itemx iso9899:199x 390@itemx c9x 391The revised ISO C standard, published in December 1999. Before 392publication, this was known as C9X@. 393 394@item gnu89 395The 1990 C standard plus GNU extensions. This is the default. 396 397@item gnu99 398@itemx gnu9x 399The 1999 C standard plus GNU extensions. 400 401@item c++98 402The 1998 ISO C++ standard plus amendments. 403 404@item gnu++98 405The same as @option{-std=c++98} plus GNU extensions. This is the 406default for C++ code. 407@end table 408 409@item -I- 410@opindex I- 411Split the include path. Any directories specified with @option{-I} 412options before @option{-I-} are searched only for headers requested with 413@code{@w{#include "@var{file}"}}; they are not searched for 414@code{@w{#include <@var{file}>}}. If additional directories are 415specified with @option{-I} options after the @option{-I-}, those 416directories are searched for all @samp{#include} directives. 417 418In addition, @option{-I-} inhibits the use of the directory of the current 419file directory as the first search directory for @code{@w{#include 420"@var{file}"}}. 421@ifset cppmanual 422@xref{Search Path}. 423@end ifset 424This option has been deprecated. 425 426@item -nostdinc 427@opindex nostdinc 428Do not search the standard system directories for header files. 429Only the directories you have specified with @option{-I} options 430(and the directory of the current file, if appropriate) are searched. 431 432@item -nostdinc++ 433@opindex nostdinc++ 434Do not search for header files in the C++-specific standard directories, 435but do still search the other standard directories. (This option is 436used when building the C++ library.) 437 438@item -include @var{file} 439@opindex include 440Process @var{file} as if @code{#include "file"} appeared as the first 441line of the primary source file. However, the first directory searched 442for @var{file} is the preprocessor's working directory @emph{instead of} 443the directory containing the main source file. If not found there, it 444is searched for in the remainder of the @code{#include "@dots{}"} search 445chain as normal. 446 447If multiple @option{-include} options are given, the files are included 448in the order they appear on the command line. 449 450@item -imacros @var{file} 451@opindex imacros 452Exactly like @option{-include}, except that any output produced by 453scanning @var{file} is thrown away. Macros it defines remain defined. 454This allows you to acquire all the macros from a header without also 455processing its declarations. 456 457All files specified by @option{-imacros} are processed before all files 458specified by @option{-include}. 459 460@item -idirafter @var{dir} 461@opindex idirafter 462Search @var{dir} for header files, but do it @emph{after} all 463directories specified with @option{-I} and the standard system directories 464have been exhausted. @var{dir} is treated as a system include directory. 465 466@item -iprefix @var{prefix} 467@opindex iprefix 468Specify @var{prefix} as the prefix for subsequent @option{-iwithprefix} 469options. If the prefix represents a directory, you should include the 470final @samp{/}. 471 472@item -iwithprefix @var{dir} 473@itemx -iwithprefixbefore @var{dir} 474@opindex iwithprefix 475@opindex iwithprefixbefore 476Append @var{dir} to the prefix specified previously with 477@option{-iprefix}, and add the resulting directory to the include search 478path. @option{-iwithprefixbefore} puts it in the same place @option{-I} 479would; @option{-iwithprefix} puts it where @option{-idirafter} would. 480 481@item -isysroot @var{dir} 482@opindex isysroot 483This option is like the @option{--sysroot} option, but applies only to 484header files. See the @option{--sysroot} option for more information. 485 486@item -imultilib @var{dir} 487@opindex imultilib 488Use @var{dir} as a subdirectory of the directory containing 489target-specific C++ headers. 490 491@item -isystem @var{dir} 492@opindex isystem 493Search @var{dir} for header files, after all directories specified by 494@option{-I} but before the standard system directories. Mark it 495as a system directory, so that it gets the same special treatment as 496is applied to the standard system directories. 497@ifset cppmanual 498@xref{System Headers}. 499@end ifset 500 501@item -iquote @var{dir} 502@opindex iquote 503Search @var{dir} only for header files requested with 504@code{@w{#include "@var{file}"}}; they are not searched for 505@code{@w{#include <@var{file}>}}, before all directories specified by 506@option{-I} and before the standard system directories. 507@ifset cppmanual 508@xref{Search Path}. 509@end ifset 510 511@item -fdollars-in-identifiers 512@opindex fdollars-in-identifiers 513@anchor{fdollars-in-identifiers} 514Accept @samp{$} in identifiers. 515@ifset cppmanual 516 @xref{Identifier characters}. 517@end ifset 518 519@item -fextended-identifiers 520@opindex fextended-identifiers 521Accept universal character names in identifiers. This option is 522experimental; in a future version of GCC, it will be enabled by 523default for C99 and C++. 524 525@item -fpreprocessed 526@opindex fpreprocessed 527Indicate to the preprocessor that the input file has already been 528preprocessed. This suppresses things like macro expansion, trigraph 529conversion, escaped newline splicing, and processing of most directives. 530The preprocessor still recognizes and removes comments, so that you can 531pass a file preprocessed with @option{-C} to the compiler without 532problems. In this mode the integrated preprocessor is little more than 533a tokenizer for the front ends. 534 535@option{-fpreprocessed} is implicit if the input file has one of the 536extensions @samp{.i}, @samp{.ii} or @samp{.mi}. These are the 537extensions that GCC uses for preprocessed files created by 538@option{-save-temps}. 539 540@item -ftabstop=@var{width} 541@opindex ftabstop 542Set the distance between tab stops. This helps the preprocessor report 543correct column numbers in warnings or errors, even if tabs appear on the 544line. If the value is less than 1 or greater than 100, the option is 545ignored. The default is 8. 546 547@item -fexec-charset=@var{charset} 548@opindex fexec-charset 549@cindex character set, execution 550Set the execution character set, used for string and character 551constants. The default is UTF-8. @var{charset} can be any encoding 552supported by the system's @code{iconv} library routine. 553 554@item -fwide-exec-charset=@var{charset} 555@opindex fwide-exec-charset 556@cindex character set, wide execution 557Set the wide execution character set, used for wide string and 558character constants. The default is UTF-32 or UTF-16, whichever 559corresponds to the width of @code{wchar_t}. As with 560@option{-fexec-charset}, @var{charset} can be any encoding supported 561by the system's @code{iconv} library routine; however, you will have 562problems with encodings that do not fit exactly in @code{wchar_t}. 563 564@item -finput-charset=@var{charset} 565@opindex finput-charset 566@cindex character set, input 567Set the input character set, used for translation from the character 568set of the input file to the source character set used by GCC@. If the 569locale does not specify, or GCC cannot get this information from the 570locale, the default is UTF-8. This can be overridden by either the locale 571or this command line option. Currently the command line option takes 572precedence if there's a conflict. @var{charset} can be any encoding 573supported by the system's @code{iconv} library routine. 574 575@item -fworking-directory 576@opindex fworking-directory 577@opindex fno-working-directory 578Enable generation of linemarkers in the preprocessor output that will 579let the compiler know the current working directory at the time of 580preprocessing. When this option is enabled, the preprocessor will 581emit, after the initial linemarker, a second linemarker with the 582current working directory followed by two slashes. GCC will use this 583directory, when it's present in the preprocessed input, as the 584directory emitted as the current working directory in some debugging 585information formats. This option is implicitly enabled if debugging 586information is enabled, but this can be inhibited with the negated 587form @option{-fno-working-directory}. If the @option{-P} flag is 588present in the command line, this option has no effect, since no 589@code{#line} directives are emitted whatsoever. 590 591@item -fno-show-column 592@opindex fno-show-column 593Do not print column numbers in diagnostics. This may be necessary if 594diagnostics are being scanned by a program that does not understand the 595column numbers, such as @command{dejagnu}. 596 597@item -A @var{predicate}=@var{answer} 598@opindex A 599Make an assertion with the predicate @var{predicate} and answer 600@var{answer}. This form is preferred to the older form @option{-A 601@var{predicate}(@var{answer})}, which is still supported, because 602it does not use shell special characters. 603@ifset cppmanual 604@xref{Assertions}. 605@end ifset 606 607@item -A -@var{predicate}=@var{answer} 608Cancel an assertion with the predicate @var{predicate} and answer 609@var{answer}. 610 611@item -dCHARS 612@var{CHARS} is a sequence of one or more of the following characters, 613and must not be preceded by a space. Other characters are interpreted 614by the compiler proper, or reserved for future versions of GCC, and so 615are silently ignored. If you specify characters whose behavior 616conflicts, the result is undefined. 617 618@table @samp 619@item M 620@opindex dM 621Instead of the normal output, generate a list of @samp{#define} 622directives for all the macros defined during the execution of the 623preprocessor, including predefined macros. This gives you a way of 624finding out what is predefined in your version of the preprocessor. 625Assuming you have no file @file{foo.h}, the command 626 627@smallexample 628touch foo.h; cpp -dM foo.h 629@end smallexample 630 631@noindent 632will show all the predefined macros. 633 634@item D 635@opindex dD 636Like @samp{M} except in two respects: it does @emph{not} include the 637predefined macros, and it outputs @emph{both} the @samp{#define} 638directives and the result of preprocessing. Both kinds of output go to 639the standard output file. 640 641@item N 642@opindex dN 643Like @samp{D}, but emit only the macro names, not their expansions. 644 645@item I 646@opindex dI 647Output @samp{#include} directives in addition to the result of 648preprocessing. 649@end table 650 651@item -P 652@opindex P 653Inhibit generation of linemarkers in the output from the preprocessor. 654This might be useful when running the preprocessor on something that is 655not C code, and will be sent to a program which might be confused by the 656linemarkers. 657@ifset cppmanual 658@xref{Preprocessor Output}. 659@end ifset 660 661@item -C 662@opindex C 663Do not discard comments. All comments are passed through to the output 664file, except for comments in processed directives, which are deleted 665along with the directive. 666 667You should be prepared for side effects when using @option{-C}; it 668causes the preprocessor to treat comments as tokens in their own right. 669For example, comments appearing at the start of what would be a 670directive line have the effect of turning that line into an ordinary 671source line, since the first token on the line is no longer a @samp{#}. 672 673@item -CC 674Do not discard comments, including during macro expansion. This is 675like @option{-C}, except that comments contained within macros are 676also passed through to the output file where the macro is expanded. 677 678In addition to the side-effects of the @option{-C} option, the 679@option{-CC} option causes all C++-style comments inside a macro 680to be converted to C-style comments. This is to prevent later use 681of that macro from inadvertently commenting out the remainder of 682the source line. 683 684The @option{-CC} option is generally used to support lint comments. 685 686@item -traditional-cpp 687@opindex traditional-cpp 688Try to imitate the behavior of old-fashioned C preprocessors, as 689opposed to ISO C preprocessors. 690@ifset cppmanual 691@xref{Traditional Mode}. 692@end ifset 693 694@item -trigraphs 695@opindex trigraphs 696Process trigraph sequences. 697@ifset cppmanual 698@xref{Initial processing}. 699@end ifset 700@ifclear cppmanual 701These are three-character sequences, all starting with @samp{??}, that 702are defined by ISO C to stand for single characters. For example, 703@samp{??/} stands for @samp{\}, so @samp{'??/n'} is a character 704constant for a newline. By default, GCC ignores trigraphs, but in 705standard-conforming modes it converts them. See the @option{-std} and 706@option{-ansi} options. 707 708The nine trigraphs and their replacements are 709 710@smallexample 711Trigraph: ??( ??) ??< ??> ??= ??/ ??' ??! ??- 712Replacement: [ ] @{ @} # \ ^ | ~ 713@end smallexample 714@end ifclear 715 716@item -remap 717@opindex remap 718Enable special code to work around file systems which only permit very 719short file names, such as MS-DOS@. 720 721@itemx --help 722@itemx --target-help 723@opindex help 724@opindex target-help 725Print text describing all the command line options instead of 726preprocessing anything. 727 728@item -v 729@opindex v 730Verbose mode. Print out GNU CPP's version number at the beginning of 731execution, and report the final form of the include path. 732 733@item -H 734@opindex H 735Print the name of each header file used, in addition to other normal 736activities. Each name is indented to show how deep in the 737@samp{#include} stack it is. Precompiled header files are also 738printed, even if they are found to be invalid; an invalid precompiled 739header file is printed with @samp{...x} and a valid one with @samp{...!} . 740 741@item -version 742@itemx --version 743@opindex version 744Print out GNU CPP's version number. With one dash, proceed to 745preprocess as normal. With two dashes, exit immediately. 746@end table 747