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annotate gcc/doc/cppopts.texi @ 63:b7f97abdc517 gcc-4.6-20100522
update gcc from gcc-4.5.0 to gcc-4.6
| author | ryoma <e075725@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Mon, 24 May 2010 12:47:05 +0900 |
| parents | a06113de4d67 |
| children | f6334be47118 |
| rev | line source |
|---|---|
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1 @c Copyright (c) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, |
|
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2 @c 2010, Free Software Foundation, Inc. |
| 0 | 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 | |
| 16 Predefine @var{name} as a macro, with definition @code{1}. | |
| 17 | |
| 18 @item -D @var{name}=@var{definition} | |
| 19 The contents of @var{definition} are tokenized and processed as if | |
| 20 they appeared during translation phase three in a @samp{#define} | |
| 21 directive. In particular, the definition will be truncated by | |
| 22 embedded newline characters. | |
| 23 | |
| 24 If you are invoking the preprocessor from a shell or shell-like | |
| 25 program you may need to use the shell's quoting syntax to protect | |
| 26 characters such as spaces that have a meaning in the shell syntax. | |
| 27 | |
| 28 If you wish to define a function-like macro on the command line, write | |
| 29 its argument list with surrounding parentheses before the equals sign | |
| 30 (if any). Parentheses are meaningful to most shells, so you will need | |
| 31 to 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 | |
| 35 are 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 | |
| 41 Cancel any previous definition of @var{name}, either built in or | |
| 42 provided with a @option{-D} option. | |
| 43 | |
| 44 @item -undef | |
| 45 @opindex undef | |
| 46 Do not predefine any system-specific or GCC-specific macros. The | |
| 47 standard predefined macros remain defined. | |
| 48 @ifset cppmanual | |
| 49 @xref{Standard Predefined Macros}. | |
| 50 @end ifset | |
| 51 | |
| 52 @item -I @var{dir} | |
| 53 @opindex I | |
| 54 Add the directory @var{dir} to the list of directories to be searched | |
| 55 for header files. | |
| 56 @ifset cppmanual | |
| 57 @xref{Search Path}. | |
| 58 @end ifset | |
| 59 Directories named by @option{-I} are searched before the standard | |
| 60 system include directories. If the directory @var{dir} is a standard | |
| 61 system include directory, the option is ignored to ensure that the | |
| 62 default search order for system directories and the special treatment | |
| 63 of system headers are not defeated | |
| 64 @ifset cppmanual | |
| 65 (@pxref{System Headers}) | |
| 66 @end ifset | |
| 67 . | |
| 68 If @var{dir} begins with @code{=}, then the @code{=} will be replaced | |
| 69 by the sysroot prefix; see @option{--sysroot} and @option{-isysroot}. | |
| 70 | |
| 71 @item -o @var{file} | |
| 72 @opindex o | |
| 73 Write output to @var{file}. This is the same as specifying @var{file} | |
| 74 as the second non-option argument to @command{cpp}. @command{gcc} has a | |
| 75 different interpretation of a second non-option argument, so you must | |
| 76 use @option{-o} to specify the output file. | |
| 77 | |
| 78 @item -Wall | |
| 79 @opindex Wall | |
| 80 Turns on all optional warnings which are desirable for normal code. | |
| 81 At present this is @option{-Wcomment}, @option{-Wtrigraphs}, | |
| 82 @option{-Wmultichar} and a warning about integer promotion causing a | |
| 83 change of sign in @code{#if} expressions. Note that many of the | |
| 84 preprocessor's warnings are on by default and have no options to | |
| 85 control them. | |
| 86 | |
| 87 @item -Wcomment | |
| 88 @itemx -Wcomments | |
| 89 @opindex Wcomment | |
| 90 @opindex Wcomments | |
| 91 Warn whenever a comment-start sequence @samp{/*} appears in a @samp{/*} | |
| 92 comment, or whenever a backslash-newline appears in a @samp{//} comment. | |
| 93 (Both forms have the same effect.) | |
| 94 | |
| 95 @item -Wtrigraphs | |
| 96 @opindex Wtrigraphs | |
| 97 @anchor{Wtrigraphs} | |
| 98 Most trigraphs in comments cannot affect the meaning of the program. | |
| 99 However, a trigraph that would form an escaped newline (@samp{??/} at | |
| 100 the end of a line) can, by changing where the comment begins or ends. | |
| 101 Therefore, only trigraphs that would form escaped newlines produce | |
| 102 warnings inside a comment. | |
| 103 | |
| 104 This option is implied by @option{-Wall}. If @option{-Wall} is not | |
| 105 given, this option is still enabled unless trigraphs are enabled. To | |
| 106 get trigraph conversion without warnings, but get the other | |
| 107 @option{-Wall} warnings, use @samp{-trigraphs -Wall -Wno-trigraphs}. | |
| 108 | |
| 109 @item -Wtraditional | |
| 110 @opindex Wtraditional | |
| 111 Warn about certain constructs that behave differently in traditional and | |
| 112 ISO C@. Also warn about ISO C constructs that have no traditional C | |
| 113 equivalent, and problematic constructs which should be avoided. | |
| 114 @ifset cppmanual | |
| 115 @xref{Traditional Mode}. | |
| 116 @end ifset | |
| 117 | |
| 118 @item -Wundef | |
| 119 @opindex Wundef | |
| 120 Warn whenever an identifier which is not a macro is encountered in an | |
| 121 @samp{#if} directive, outside of @samp{defined}. Such identifiers are | |
| 122 replaced with zero. | |
| 123 | |
| 124 @item -Wunused-macros | |
| 125 @opindex Wunused-macros | |
| 126 Warn about macros defined in the main file that are unused. A macro | |
| 127 is @dfn{used} if it is expanded or tested for existence at least once. | |
| 128 The preprocessor will also warn if the macro has not been used at the | |
| 129 time it is redefined or undefined. | |
| 130 | |
| 131 Built-in macros, macros defined on the command line, and macros | |
| 132 defined in include files are not warned about. | |
| 133 | |
| 134 @emph{Note:} If a macro is actually used, but only used in skipped | |
| 135 conditional blocks, then CPP will report it as unused. To avoid the | |
| 136 warning in such a case, you might improve the scope of the macro's | |
| 137 definition by, for example, moving it into the first skipped block. | |
| 138 Alternatively, you could provide a dummy use with something like: | |
| 139 | |
| 140 @smallexample | |
| 141 #if defined the_macro_causing_the_warning | |
| 142 #endif | |
| 143 @end smallexample | |
| 144 | |
| 145 @item -Wendif-labels | |
| 146 @opindex Wendif-labels | |
| 147 Warn whenever an @samp{#else} or an @samp{#endif} are followed by text. | |
| 148 This usually happens in code of the form | |
| 149 | |
| 150 @smallexample | |
| 151 #if FOO | |
| 152 @dots{} | |
| 153 #else FOO | |
| 154 @dots{} | |
| 155 #endif FOO | |
| 156 @end smallexample | |
| 157 | |
| 158 @noindent | |
| 159 The second and third @code{FOO} should be in comments, but often are not | |
| 160 in older programs. This warning is on by default. | |
| 161 | |
| 162 @item -Werror | |
| 163 @opindex Werror | |
| 164 Make all warnings into hard errors. Source code which triggers warnings | |
| 165 will be rejected. | |
| 166 | |
| 167 @item -Wsystem-headers | |
| 168 @opindex Wsystem-headers | |
| 169 Issue warnings for code in system headers. These are normally unhelpful | |
| 170 in finding bugs in your own code, therefore suppressed. If you are | |
| 171 responsible for the system library, you may want to see them. | |
| 172 | |
| 173 @item -w | |
| 174 @opindex w | |
| 175 Suppress all warnings, including those which GNU CPP issues by default. | |
| 176 | |
| 177 @item -pedantic | |
| 178 @opindex pedantic | |
| 179 Issue all the mandatory diagnostics listed in the C standard. Some of | |
| 180 them are left out by default, since they trigger frequently on harmless | |
| 181 code. | |
| 182 | |
| 183 @item -pedantic-errors | |
| 184 @opindex pedantic-errors | |
| 185 Issue all the mandatory diagnostics, and make all mandatory diagnostics | |
| 186 into errors. This includes mandatory diagnostics that GCC issues | |
| 187 without @samp{-pedantic} but treats as warnings. | |
| 188 | |
| 189 @item -M | |
| 190 @opindex M | |
| 191 @cindex make | |
| 192 @cindex dependencies, make | |
| 193 Instead of outputting the result of preprocessing, output a rule | |
| 194 suitable for @command{make} describing the dependencies of the main | |
| 195 source file. The preprocessor outputs one @command{make} rule containing | |
| 196 the object file name for that source file, a colon, and the names of all | |
| 197 the included files, including those coming from @option{-include} or | |
| 198 @option{-imacros} command line options. | |
| 199 | |
| 200 Unless specified explicitly (with @option{-MT} or @option{-MQ}), the | |
| 201 object file name consists of the name of the source file with any | |
| 202 suffix replaced with object file suffix and with any leading directory | |
| 203 parts removed. If there are many included files then the rule is | |
| 204 split into several lines using @samp{\}-newline. The rule has no | |
| 205 commands. | |
| 206 | |
| 207 This option does not suppress the preprocessor's debug output, such as | |
| 208 @option{-dM}. To avoid mixing such debug output with the dependency | |
| 209 rules you should explicitly specify the dependency output file with | |
| 210 @option{-MF}, or use an environment variable like | |
| 211 @env{DEPENDENCIES_OUTPUT} (@pxref{Environment Variables}). Debug output | |
| 212 will still be sent to the regular output stream as normal. | |
| 213 | |
| 214 Passing @option{-M} to the driver implies @option{-E}, and suppresses | |
| 215 warnings with an implicit @option{-w}. | |
| 216 | |
| 217 @item -MM | |
| 218 @opindex MM | |
| 219 Like @option{-M} but do not mention header files that are found in | |
| 220 system header directories, nor header files that are included, | |
| 221 directly or indirectly, from such a header. | |
| 222 | |
| 223 This implies that the choice of angle brackets or double quotes in an | |
| 224 @samp{#include} directive does not in itself determine whether that | |
| 225 header will appear in @option{-MM} dependency output. This is a | |
| 226 slight change in semantics from GCC versions 3.0 and earlier. | |
| 227 | |
| 228 @anchor{dashMF} | |
| 229 @item -MF @var{file} | |
| 230 @opindex MF | |
| 231 When used with @option{-M} or @option{-MM}, specifies a | |
| 232 file to write the dependencies to. If no @option{-MF} switch is given | |
| 233 the preprocessor sends the rules to the same place it would have sent | |
| 234 preprocessed output. | |
| 235 | |
| 236 When used with the driver options @option{-MD} or @option{-MMD}, | |
| 237 @option{-MF} overrides the default dependency output file. | |
| 238 | |
| 239 @item -MG | |
| 240 @opindex MG | |
| 241 In conjunction with an option such as @option{-M} requesting | |
| 242 dependency generation, @option{-MG} assumes missing header files are | |
| 243 generated files and adds them to the dependency list without raising | |
| 244 an error. The dependency filename is taken directly from the | |
| 245 @code{#include} directive without prepending any path. @option{-MG} | |
| 246 also suppresses preprocessed output, as a missing header file renders | |
| 247 this useless. | |
| 248 | |
| 249 This feature is used in automatic updating of makefiles. | |
| 250 | |
| 251 @item -MP | |
| 252 @opindex MP | |
| 253 This option instructs CPP to add a phony target for each dependency | |
| 254 other than the main file, causing each to depend on nothing. These | |
| 255 dummy rules work around errors @command{make} gives if you remove header | |
| 256 files without updating the @file{Makefile} to match. | |
| 257 | |
| 258 This is typical output: | |
| 259 | |
| 260 @smallexample | |
| 261 test.o: test.c test.h | |
| 262 | |
| 263 test.h: | |
| 264 @end smallexample | |
| 265 | |
| 266 @item -MT @var{target} | |
| 267 @opindex MT | |
| 268 | |
| 269 Change the target of the rule emitted by dependency generation. By | |
| 270 default CPP takes the name of the main input file, deletes any | |
| 271 directory components and any file suffix such as @samp{.c}, and | |
| 272 appends the platform's usual object suffix. The result is the target. | |
| 273 | |
| 274 An @option{-MT} option will set the target to be exactly the string you | |
| 275 specify. If you want multiple targets, you can specify them as a single | |
| 276 argument to @option{-MT}, or use multiple @option{-MT} options. | |
| 277 | |
| 278 For example, @option{@w{-MT '$(objpfx)foo.o'}} might give | |
| 279 | |
| 280 @smallexample | |
| 281 $(objpfx)foo.o: foo.c | |
| 282 @end smallexample | |
| 283 | |
| 284 @item -MQ @var{target} | |
| 285 @opindex MQ | |
| 286 | |
| 287 Same as @option{-MT}, but it quotes any characters which are special to | |
| 288 Make. @option{@w{-MQ '$(objpfx)foo.o'}} gives | |
| 289 | |
| 290 @smallexample | |
| 291 $$(objpfx)foo.o: foo.c | |
| 292 @end smallexample | |
| 293 | |
| 294 The default target is automatically quoted, as if it were given with | |
| 295 @option{-MQ}. | |
| 296 | |
| 297 @item -MD | |
| 298 @opindex MD | |
| 299 @option{-MD} is equivalent to @option{-M -MF @var{file}}, except that | |
| 300 @option{-E} is not implied. The driver determines @var{file} based on | |
| 301 whether an @option{-o} option is given. If it is, the driver uses its | |
| 302 argument but with a suffix of @file{.d}, otherwise it takes the name | |
| 303 of the input file, removes any directory components and suffix, and | |
| 304 applies a @file{.d} suffix. | |
| 305 | |
| 306 If @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} | |
| 309 is understood to specify a target object file. | |
| 310 | |
| 311 Since @option{-E} is not implied, @option{-MD} can be used to generate | |
| 312 a dependency output file as a side-effect of the compilation process. | |
| 313 | |
| 314 @item -MMD | |
| 315 @opindex MMD | |
| 316 Like @option{-MD} except mention only user header files, not system | |
| 317 header files. | |
| 318 | |
| 319 @ifclear cppmanual | |
| 320 @item -fpch-deps | |
| 321 @opindex fpch-deps | |
| 322 When using precompiled headers (@pxref{Precompiled Headers}), this flag | |
| 323 will cause the dependency-output flags to also list the files from the | |
| 324 precompiled header's dependencies. If not specified only the | |
| 325 precompiled header would be listed and not the files that were used to | |
| 326 create it because those files are not consulted when a precompiled | |
| 327 header is used. | |
| 328 | |
| 329 @item -fpch-preprocess | |
| 330 @opindex fpch-preprocess | |
| 331 This option allows use of a precompiled header (@pxref{Precompiled | |
| 332 Headers}) together with @option{-E}. It inserts a special @code{#pragma}, | |
| 333 @code{#pragma GCC pch_preprocess "<filename>"} in the output to mark | |
| 334 the place where the precompiled header was found, and its filename. When | |
| 335 @option{-fpreprocessed} is in use, GCC recognizes this @code{#pragma} and | |
| 336 loads the PCH@. | |
| 337 | |
| 338 This option is off by default, because the resulting preprocessed output | |
| 339 is only really suitable as input to GCC@. It is switched on by | |
| 340 @option{-save-temps}. | |
| 341 | |
| 342 You should not write this @code{#pragma} in your own code, but it is | |
| 343 safe to edit the filename if the PCH file is available in a different | |
| 344 location. The filename may be absolute or it may be relative to GCC's | |
| 345 current 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 | |
| 353 Specify the source language: C, C++, Objective-C, or assembly. This has | |
| 354 nothing to do with standards conformance or extensions; it merely | |
| 355 selects which base syntax to expect. If you give none of these options, | |
| 356 cpp will deduce the language from the extension of the source file: | |
| 357 @samp{.c}, @samp{.cc}, @samp{.m}, or @samp{.S}. Some other common | |
| 358 extensions for C++ and assembly are also recognized. If cpp does not | |
| 359 recognize the extension, it will treat the file as C; this is the most | |
| 360 generic mode. | |
| 361 | |
| 362 @emph{Note:} Previous versions of cpp accepted a @option{-lang} option | |
| 363 which selected both the language and the standards conformance level. | |
| 364 This option has been removed, because it conflicts with the @option{-l} | |
| 365 option. | |
| 366 | |
| 367 @item -std=@var{standard} | |
| 368 @itemx -ansi | |
| 369 @opindex ansi | |
| 370 @opindex std= | |
| 371 Specify the standard to which the code should conform. Currently CPP | |
| 372 knows about C and C++ standards; others may be added in the future. | |
| 373 | |
| 374 @var{standard} | |
| 375 may be one of: | |
| 376 @table @code | |
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377 @item c90 |
| 0 | 378 @itemx c89 |
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379 @itemx iso9899:1990 |
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380 The ISO C standard from 1990. @samp{c90} is the customary shorthand for |
| 0 | 381 this version of the standard. |
| 382 | |
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383 The @option{-ansi} option is equivalent to @option{-std=c90}. |
| 0 | 384 |
| 385 @item iso9899:199409 | |
| 386 The 1990 C standard, as amended in 1994. | |
| 387 | |
| 388 @item iso9899:1999 | |
| 389 @itemx c99 | |
| 390 @itemx iso9899:199x | |
| 391 @itemx c9x | |
| 392 The revised ISO C standard, published in December 1999. Before | |
| 393 publication, this was known as C9X@. | |
| 394 | |
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395 @item c1x |
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396 The next version of the ISO C standard, still under development. |
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397 |
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398 @item gnu90 |
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399 @itemx gnu89 |
| 0 | 400 The 1990 C standard plus GNU extensions. This is the default. |
| 401 | |
| 402 @item gnu99 | |
| 403 @itemx gnu9x | |
| 404 The 1999 C standard plus GNU extensions. | |
| 405 | |
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406 @item gnu1x |
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407 The next version of the ISO C standard, still under development, plus |
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408 GNU extensions. |
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409 |
| 0 | 410 @item c++98 |
| 411 The 1998 ISO C++ standard plus amendments. | |
| 412 | |
| 413 @item gnu++98 | |
| 414 The same as @option{-std=c++98} plus GNU extensions. This is the | |
| 415 default for C++ code. | |
| 416 @end table | |
| 417 | |
| 418 @item -I- | |
| 419 @opindex I- | |
| 420 Split the include path. Any directories specified with @option{-I} | |
| 421 options before @option{-I-} are searched only for headers requested with | |
| 422 @code{@w{#include "@var{file}"}}; they are not searched for | |
| 423 @code{@w{#include <@var{file}>}}. If additional directories are | |
| 424 specified with @option{-I} options after the @option{-I-}, those | |
| 425 directories are searched for all @samp{#include} directives. | |
| 426 | |
| 427 In addition, @option{-I-} inhibits the use of the directory of the current | |
| 428 file directory as the first search directory for @code{@w{#include | |
| 429 "@var{file}"}}. | |
| 430 @ifset cppmanual | |
| 431 @xref{Search Path}. | |
| 432 @end ifset | |
| 433 This option has been deprecated. | |
| 434 | |
| 435 @item -nostdinc | |
| 436 @opindex nostdinc | |
| 437 Do not search the standard system directories for header files. | |
| 438 Only the directories you have specified with @option{-I} options | |
| 439 (and the directory of the current file, if appropriate) are searched. | |
| 440 | |
| 441 @item -nostdinc++ | |
| 442 @opindex nostdinc++ | |
| 443 Do not search for header files in the C++-specific standard directories, | |
| 444 but do still search the other standard directories. (This option is | |
| 445 used when building the C++ library.) | |
| 446 | |
| 447 @item -include @var{file} | |
| 448 @opindex include | |
| 449 Process @var{file} as if @code{#include "file"} appeared as the first | |
| 450 line of the primary source file. However, the first directory searched | |
| 451 for @var{file} is the preprocessor's working directory @emph{instead of} | |
| 452 the directory containing the main source file. If not found there, it | |
| 453 is searched for in the remainder of the @code{#include "@dots{}"} search | |
| 454 chain as normal. | |
| 455 | |
| 456 If multiple @option{-include} options are given, the files are included | |
| 457 in the order they appear on the command line. | |
| 458 | |
| 459 @item -imacros @var{file} | |
| 460 @opindex imacros | |
| 461 Exactly like @option{-include}, except that any output produced by | |
| 462 scanning @var{file} is thrown away. Macros it defines remain defined. | |
| 463 This allows you to acquire all the macros from a header without also | |
| 464 processing its declarations. | |
| 465 | |
| 466 All files specified by @option{-imacros} are processed before all files | |
| 467 specified by @option{-include}. | |
| 468 | |
| 469 @item -idirafter @var{dir} | |
| 470 @opindex idirafter | |
| 471 Search @var{dir} for header files, but do it @emph{after} all | |
| 472 directories specified with @option{-I} and the standard system directories | |
| 473 have been exhausted. @var{dir} is treated as a system include directory. | |
| 474 If @var{dir} begins with @code{=}, then the @code{=} will be replaced | |
| 475 by the sysroot prefix; see @option{--sysroot} and @option{-isysroot}. | |
| 476 | |
| 477 @item -iprefix @var{prefix} | |
| 478 @opindex iprefix | |
| 479 Specify @var{prefix} as the prefix for subsequent @option{-iwithprefix} | |
| 480 options. If the prefix represents a directory, you should include the | |
| 481 final @samp{/}. | |
| 482 | |
| 483 @item -iwithprefix @var{dir} | |
| 484 @itemx -iwithprefixbefore @var{dir} | |
| 485 @opindex iwithprefix | |
| 486 @opindex iwithprefixbefore | |
| 487 Append @var{dir} to the prefix specified previously with | |
| 488 @option{-iprefix}, and add the resulting directory to the include search | |
| 489 path. @option{-iwithprefixbefore} puts it in the same place @option{-I} | |
| 490 would; @option{-iwithprefix} puts it where @option{-idirafter} would. | |
| 491 | |
| 492 @item -isysroot @var{dir} | |
| 493 @opindex isysroot | |
| 494 This option is like the @option{--sysroot} option, but applies only to | |
| 495 header files. See the @option{--sysroot} option for more information. | |
| 496 | |
| 497 @item -imultilib @var{dir} | |
| 498 @opindex imultilib | |
| 499 Use @var{dir} as a subdirectory of the directory containing | |
| 500 target-specific C++ headers. | |
| 501 | |
| 502 @item -isystem @var{dir} | |
| 503 @opindex isystem | |
| 504 Search @var{dir} for header files, after all directories specified by | |
| 505 @option{-I} but before the standard system directories. Mark it | |
| 506 as a system directory, so that it gets the same special treatment as | |
| 507 is applied to the standard system directories. | |
| 508 @ifset cppmanual | |
| 509 @xref{System Headers}. | |
| 510 @end ifset | |
| 511 If @var{dir} begins with @code{=}, then the @code{=} will be replaced | |
| 512 by the sysroot prefix; see @option{--sysroot} and @option{-isysroot}. | |
| 513 | |
| 514 @item -iquote @var{dir} | |
| 515 @opindex iquote | |
| 516 Search @var{dir} only for header files requested with | |
| 517 @code{@w{#include "@var{file}"}}; they are not searched for | |
| 518 @code{@w{#include <@var{file}>}}, before all directories specified by | |
| 519 @option{-I} and before the standard system directories. | |
| 520 @ifset cppmanual | |
| 521 @xref{Search Path}. | |
| 522 @end ifset | |
| 523 If @var{dir} begins with @code{=}, then the @code{=} will be replaced | |
| 524 by the sysroot prefix; see @option{--sysroot} and @option{-isysroot}. | |
| 525 | |
| 526 @item -fdirectives-only | |
| 527 @opindex fdirectives-only | |
| 528 When preprocessing, handle directives, but do not expand macros. | |
| 529 | |
| 530 The option's behavior depends on the @option{-E} and @option{-fpreprocessed} | |
| 531 options. | |
| 532 | |
| 533 With @option{-E}, preprocessing is limited to the handling of directives | |
| 534 such as @code{#define}, @code{#ifdef}, and @code{#error}. Other | |
| 535 preprocessor operations, such as macro expansion and trigraph | |
| 536 conversion are not performed. In addition, the @option{-dD} option is | |
| 537 implicitly enabled. | |
| 538 | |
| 539 With @option{-fpreprocessed}, predefinition of command line and most | |
| 540 builtin macros is disabled. Macros such as @code{__LINE__}, which are | |
| 541 contextually dependent, are handled normally. This enables compilation of | |
| 542 files previously preprocessed with @code{-E -fdirectives-only}. | |
| 543 | |
| 544 With both @option{-E} and @option{-fpreprocessed}, the rules for | |
| 545 @option{-fpreprocessed} take precedence. This enables full preprocessing of | |
| 546 files previously preprocessed with @code{-E -fdirectives-only}. | |
| 547 | |
| 548 @item -fdollars-in-identifiers | |
| 549 @opindex fdollars-in-identifiers | |
| 550 @anchor{fdollars-in-identifiers} | |
| 551 Accept @samp{$} in identifiers. | |
| 552 @ifset cppmanual | |
| 553 @xref{Identifier characters}. | |
| 554 @end ifset | |
| 555 | |
| 556 @item -fextended-identifiers | |
| 557 @opindex fextended-identifiers | |
| 558 Accept universal character names in identifiers. This option is | |
| 559 experimental; in a future version of GCC, it will be enabled by | |
| 560 default for C99 and C++. | |
| 561 | |
| 562 @item -fpreprocessed | |
| 563 @opindex fpreprocessed | |
| 564 Indicate to the preprocessor that the input file has already been | |
| 565 preprocessed. This suppresses things like macro expansion, trigraph | |
| 566 conversion, escaped newline splicing, and processing of most directives. | |
| 567 The preprocessor still recognizes and removes comments, so that you can | |
| 568 pass a file preprocessed with @option{-C} to the compiler without | |
| 569 problems. In this mode the integrated preprocessor is little more than | |
| 570 a tokenizer for the front ends. | |
| 571 | |
| 572 @option{-fpreprocessed} is implicit if the input file has one of the | |
| 573 extensions @samp{.i}, @samp{.ii} or @samp{.mi}. These are the | |
| 574 extensions that GCC uses for preprocessed files created by | |
| 575 @option{-save-temps}. | |
| 576 | |
| 577 @item -ftabstop=@var{width} | |
| 578 @opindex ftabstop | |
| 579 Set the distance between tab stops. This helps the preprocessor report | |
| 580 correct column numbers in warnings or errors, even if tabs appear on the | |
| 581 line. If the value is less than 1 or greater than 100, the option is | |
| 582 ignored. The default is 8. | |
| 583 | |
| 584 @item -fexec-charset=@var{charset} | |
| 585 @opindex fexec-charset | |
| 586 @cindex character set, execution | |
| 587 Set the execution character set, used for string and character | |
| 588 constants. The default is UTF-8. @var{charset} can be any encoding | |
| 589 supported by the system's @code{iconv} library routine. | |
| 590 | |
| 591 @item -fwide-exec-charset=@var{charset} | |
| 592 @opindex fwide-exec-charset | |
| 593 @cindex character set, wide execution | |
| 594 Set the wide execution character set, used for wide string and | |
| 595 character constants. The default is UTF-32 or UTF-16, whichever | |
| 596 corresponds to the width of @code{wchar_t}. As with | |
| 597 @option{-fexec-charset}, @var{charset} can be any encoding supported | |
| 598 by the system's @code{iconv} library routine; however, you will have | |
| 599 problems with encodings that do not fit exactly in @code{wchar_t}. | |
| 600 | |
| 601 @item -finput-charset=@var{charset} | |
| 602 @opindex finput-charset | |
| 603 @cindex character set, input | |
| 604 Set the input character set, used for translation from the character | |
| 605 set of the input file to the source character set used by GCC@. If the | |
| 606 locale does not specify, or GCC cannot get this information from the | |
| 607 locale, the default is UTF-8. This can be overridden by either the locale | |
| 608 or this command line option. Currently the command line option takes | |
| 609 precedence if there's a conflict. @var{charset} can be any encoding | |
| 610 supported by the system's @code{iconv} library routine. | |
| 611 | |
| 612 @item -fworking-directory | |
| 613 @opindex fworking-directory | |
| 614 @opindex fno-working-directory | |
| 615 Enable generation of linemarkers in the preprocessor output that will | |
| 616 let the compiler know the current working directory at the time of | |
| 617 preprocessing. When this option is enabled, the preprocessor will | |
| 618 emit, after the initial linemarker, a second linemarker with the | |
| 619 current working directory followed by two slashes. GCC will use this | |
| 620 directory, when it's present in the preprocessed input, as the | |
| 621 directory emitted as the current working directory in some debugging | |
| 622 information formats. This option is implicitly enabled if debugging | |
| 623 information is enabled, but this can be inhibited with the negated | |
| 624 form @option{-fno-working-directory}. If the @option{-P} flag is | |
| 625 present in the command line, this option has no effect, since no | |
| 626 @code{#line} directives are emitted whatsoever. | |
| 627 | |
| 628 @item -fno-show-column | |
| 629 @opindex fno-show-column | |
| 630 Do not print column numbers in diagnostics. This may be necessary if | |
| 631 diagnostics are being scanned by a program that does not understand the | |
| 632 column numbers, such as @command{dejagnu}. | |
| 633 | |
| 634 @item -A @var{predicate}=@var{answer} | |
| 635 @opindex A | |
| 636 Make an assertion with the predicate @var{predicate} and answer | |
| 637 @var{answer}. This form is preferred to the older form @option{-A | |
| 638 @var{predicate}(@var{answer})}, which is still supported, because | |
| 639 it does not use shell special characters. | |
| 640 @ifset cppmanual | |
| 641 @xref{Obsolete Features}. | |
| 642 @end ifset | |
| 643 | |
| 644 @item -A -@var{predicate}=@var{answer} | |
| 645 Cancel an assertion with the predicate @var{predicate} and answer | |
| 646 @var{answer}. | |
| 647 | |
| 648 @item -dCHARS | |
| 649 @var{CHARS} is a sequence of one or more of the following characters, | |
| 650 and must not be preceded by a space. Other characters are interpreted | |
| 651 by the compiler proper, or reserved for future versions of GCC, and so | |
| 652 are silently ignored. If you specify characters whose behavior | |
| 653 conflicts, the result is undefined. | |
| 654 | |
| 655 @table @samp | |
| 656 @item M | |
| 657 @opindex dM | |
| 658 Instead of the normal output, generate a list of @samp{#define} | |
| 659 directives for all the macros defined during the execution of the | |
| 660 preprocessor, including predefined macros. This gives you a way of | |
| 661 finding out what is predefined in your version of the preprocessor. | |
| 662 Assuming you have no file @file{foo.h}, the command | |
| 663 | |
| 664 @smallexample | |
| 665 touch foo.h; cpp -dM foo.h | |
| 666 @end smallexample | |
| 667 | |
| 668 @noindent | |
| 669 will show all the predefined macros. | |
| 670 | |
| 671 If you use @option{-dM} without the @option{-E} option, @option{-dM} is | |
| 672 interpreted as a synonym for @option{-fdump-rtl-mach}. | |
| 673 @xref{Debugging Options, , ,gcc}. | |
| 674 | |
| 675 @item D | |
| 676 @opindex dD | |
| 677 Like @samp{M} except in two respects: it does @emph{not} include the | |
| 678 predefined macros, and it outputs @emph{both} the @samp{#define} | |
| 679 directives and the result of preprocessing. Both kinds of output go to | |
| 680 the standard output file. | |
| 681 | |
| 682 @item N | |
| 683 @opindex dN | |
| 684 Like @samp{D}, but emit only the macro names, not their expansions. | |
| 685 | |
| 686 @item I | |
| 687 @opindex dI | |
| 688 Output @samp{#include} directives in addition to the result of | |
| 689 preprocessing. | |
| 690 | |
| 691 @item U | |
| 692 @opindex dU | |
| 693 Like @samp{D} except that only macros that are expanded, or whose | |
| 694 definedness is tested in preprocessor directives, are output; the | |
| 695 output is delayed until the use or test of the macro; and | |
| 696 @samp{#undef} directives are also output for macros tested but | |
| 697 undefined at the time. | |
| 698 @end table | |
| 699 | |
| 700 @item -P | |
| 701 @opindex P | |
| 702 Inhibit generation of linemarkers in the output from the preprocessor. | |
| 703 This might be useful when running the preprocessor on something that is | |
| 704 not C code, and will be sent to a program which might be confused by the | |
| 705 linemarkers. | |
| 706 @ifset cppmanual | |
| 707 @xref{Preprocessor Output}. | |
| 708 @end ifset | |
| 709 | |
| 710 @item -C | |
| 711 @opindex C | |
| 712 Do not discard comments. All comments are passed through to the output | |
| 713 file, except for comments in processed directives, which are deleted | |
| 714 along with the directive. | |
| 715 | |
| 716 You should be prepared for side effects when using @option{-C}; it | |
| 717 causes the preprocessor to treat comments as tokens in their own right. | |
| 718 For example, comments appearing at the start of what would be a | |
| 719 directive line have the effect of turning that line into an ordinary | |
| 720 source line, since the first token on the line is no longer a @samp{#}. | |
| 721 | |
| 722 @item -CC | |
| 723 Do not discard comments, including during macro expansion. This is | |
| 724 like @option{-C}, except that comments contained within macros are | |
| 725 also passed through to the output file where the macro is expanded. | |
| 726 | |
| 727 In addition to the side-effects of the @option{-C} option, the | |
| 728 @option{-CC} option causes all C++-style comments inside a macro | |
| 729 to be converted to C-style comments. This is to prevent later use | |
| 730 of that macro from inadvertently commenting out the remainder of | |
| 731 the source line. | |
| 732 | |
| 733 The @option{-CC} option is generally used to support lint comments. | |
| 734 | |
| 735 @item -traditional-cpp | |
| 736 @opindex traditional-cpp | |
| 737 Try to imitate the behavior of old-fashioned C preprocessors, as | |
| 738 opposed to ISO C preprocessors. | |
| 739 @ifset cppmanual | |
| 740 @xref{Traditional Mode}. | |
| 741 @end ifset | |
| 742 | |
| 743 @item -trigraphs | |
| 744 @opindex trigraphs | |
| 745 Process trigraph sequences. | |
| 746 @ifset cppmanual | |
| 747 @xref{Initial processing}. | |
| 748 @end ifset | |
| 749 @ifclear cppmanual | |
| 750 These are three-character sequences, all starting with @samp{??}, that | |
| 751 are defined by ISO C to stand for single characters. For example, | |
| 752 @samp{??/} stands for @samp{\}, so @samp{'??/n'} is a character | |
| 753 constant for a newline. By default, GCC ignores trigraphs, but in | |
| 754 standard-conforming modes it converts them. See the @option{-std} and | |
| 755 @option{-ansi} options. | |
| 756 | |
| 757 The nine trigraphs and their replacements are | |
| 758 | |
| 759 @smallexample | |
| 760 Trigraph: ??( ??) ??< ??> ??= ??/ ??' ??! ??- | |
| 761 Replacement: [ ] @{ @} # \ ^ | ~ | |
| 762 @end smallexample | |
| 763 @end ifclear | |
| 764 | |
| 765 @item -remap | |
| 766 @opindex remap | |
| 767 Enable special code to work around file systems which only permit very | |
| 768 short file names, such as MS-DOS@. | |
| 769 | |
| 770 @itemx --help | |
| 771 @itemx --target-help | |
| 772 @opindex help | |
| 773 @opindex target-help | |
| 774 Print text describing all the command line options instead of | |
| 775 preprocessing anything. | |
| 776 | |
| 777 @item -v | |
| 778 @opindex v | |
| 779 Verbose mode. Print out GNU CPP's version number at the beginning of | |
| 780 execution, and report the final form of the include path. | |
| 781 | |
| 782 @item -H | |
| 783 @opindex H | |
| 784 Print the name of each header file used, in addition to other normal | |
| 785 activities. Each name is indented to show how deep in the | |
| 786 @samp{#include} stack it is. Precompiled header files are also | |
| 787 printed, even if they are found to be invalid; an invalid precompiled | |
| 788 header file is printed with @samp{...x} and a valid one with @samp{...!} . | |
| 789 | |
| 790 @item -version | |
| 791 @itemx --version | |
| 792 @opindex version | |
| 793 Print out GNU CPP's version number. With one dash, proceed to | |
| 794 preprocess as normal. With two dashes, exit immediately. | |
| 795 @end table |