1 ; Options for the C, ObjC, C++ and ObjC++ front ends.
2 ; Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
3 ; Free Software Foundation, Inc.
5 ; This file is part of GCC.
7 ; GCC is free software; you can redistribute it and/or modify it under
8 ; the terms of the GNU General Public License as published by the Free
9 ; Software Foundation; either version 3, or (at your option) any later
12 ; GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 ; WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 ; FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 ; You should have received a copy of the GNU General Public License
18 ; along with GCC; see the file COPYING3. If not see
19 ; <http://www.gnu.org/licenses/>.
21 ; See the GCC internals manual for a description of this file's format.
23 ; Please try to keep this file in ASCII collating order.
38 C ObjC C++ ObjC++ Joined Separate
41 C ObjC C++ ObjC++ Joined Separate
42 -A<question>=<answer> Assert the <answer> to <question>. Putting '-' before <question> disables the <answer> to <question>
46 Do not discard comments
50 Do not discard comments in macro expansions
53 C ObjC C++ ObjC++ Joined Separate
54 -D<macro>[=<val>] Define a <macro> with <val> as its value. If just <macro> is given, <val> is taken to be 1
57 C ObjC C++ ObjC++ Undocumented
60 C ObjC C++ ObjC++ Joined Separate
61 -F <dir> Add <dir> to the end of the main framework include path
65 Print the name of header files as they are used
68 C ObjC C++ ObjC++ Joined Separate
69 -I <dir> Add <dir> to the end of the main include path
73 Generate make dependencies
76 C ObjC C++ ObjC++ Separate
77 Generate make dependencies and compile
80 C ObjC C++ ObjC++ Joined Separate
81 -MF <file> Write dependency output to the given file
85 Treat missing header files as generated files
89 Like -M but ignore system header files
92 C ObjC C++ ObjC++ Separate
93 Like -MD but ignore system header files
97 Generate phony targets for all headers
100 C ObjC C++ ObjC++ Joined Separate
101 -MQ <target> Add a MAKE-quoted target
104 C ObjC C++ ObjC++ Joined Separate
105 -MT <target> Add an unquoted target
109 Do not generate #line directives
112 C ObjC C++ ObjC++ Joined Separate
113 -U<macro> Undefine <macro>
116 C ObjC C++ ObjC++ LTO Var(warn_abi) Warning
117 Warn about things that will change when compiling with an ABI-compliant compiler
120 C ObjC C++ ObjC++ LTO Var(warn_psabi) Init(1) Undocumented
123 C ObjC C++ ObjC++ Var(warn_address) Warning
124 Warn about suspicious uses of memory addresses
127 C ObjC C++ ObjC++ Warning
128 Enable most warning messages
131 ObjC ObjC++ Var(warn_assign_intercept) Warning
132 Warn whenever an Objective-C assignment is being intercepted by the garbage collector
135 C ObjC Var(warn_bad_function_cast) Warning
136 Warn about casting functions to incompatible types
138 Wbuiltin-macro-redefined
139 C ObjC C++ ObjC++ Warning
140 Warn when a built-in preprocessor macro is undefined or redefined
143 C ObjC Var(warn_cxx_compat) Warning
144 Warn about C constructs that are not in the common subset of C and C++
147 C++ ObjC++ Var(warn_cxx0x_compat) Warning
148 Warn about C++ constructs whose meaning differs between ISO C++ 1998 and ISO C++ 200x
151 C ObjC C++ ObjC++ Var(warn_cast_qual) Warning
152 Warn about casts which discard qualifiers
155 C ObjC C++ ObjC++ Var(warn_char_subscripts) Warning
156 Warn about subscripts whose type is \"char\"
159 C ObjC C++ ObjC++ Var(warn_clobbered) Init(-1) Warning
160 Warn about variables that might be changed by \"longjmp\" or \"vfork\"
163 C ObjC C++ ObjC++ Warning
164 Warn about possibly nested block comments, and C++ comments spanning more than one physical line
167 C ObjC C++ ObjC++ Warning
168 Synonym for -Wcomment
171 C ObjC C++ ObjC++ Var(warn_conversion) Warning
172 Warn for implicit type conversions that may change a value
175 C++ ObjC++ Var(warn_conversion_null) Init(1) Warning
176 Warn for converting NULL from/to a non-pointer type
179 C ObjC C++ ObjC++ Var(warn_sign_conversion) Init(-1)
180 Warn for implicit type conversions between signed and unsigned integers
183 C++ ObjC++ Var(warn_ctor_dtor_privacy) Warning
184 Warn when all constructors and destructors are private
186 Wdeclaration-after-statement
187 C ObjC Var(warn_declaration_after_statement) Warning
188 Warn when a declaration is found after a statement
191 C C++ ObjC ObjC++ Var(warn_deprecated) Init(1) Warning
192 Warn if a deprecated compiler feature, class, method, or field is used
195 C ObjC C++ ObjC++ Var(warn_div_by_zero) Init(1) Warning
196 Warn about compile-time integer division by zero
199 C++ ObjC++ Var(warn_ecpp) Warning
200 Warn about violations of Effective C++ style rules
203 C ObjC C++ ObjC++ Var(warn_empty_body) Init(-1) Warning
204 Warn about an empty body in an if or else statement
207 C ObjC C++ ObjC++ Warning
208 Warn about stray tokens after #elif and #endif
211 C ObjC C++ ObjC++ Var(warn_enum_compare) Init(-1) Warning
212 Warn about comparison of different enum types
216 ; Documented in common.opt
218 Werror-implicit-function-declaration
219 C ObjC RejectNegative Warning
220 This switch is deprecated; use -Werror=implicit-function-declaration instead
223 C ObjC C++ ObjC++ Var(warn_float_equal) Warning
224 Warn if testing floating point numbers for equality
227 C ObjC C++ ObjC++ Warning
228 Warn about printf/scanf/strftime/strfmon format string anomalies
231 C ObjC C++ ObjC++ Var(warn_format_extra_args) Warning
232 Warn if passing too many arguments to a function for its format string
235 C ObjC C++ ObjC++ Var(warn_format_nonliteral) Warning
236 Warn about format strings that are not literals
239 C ObjC C++ ObjC++ Var(warn_format_contains_nul) Warning
240 Warn about format strings that contain NUL bytes
243 C ObjC C++ ObjC++ Var(warn_format_security) Warning
244 Warn about possible security problems with format functions
247 C ObjC C++ ObjC++ Var(warn_format_y2k) Warning
248 Warn about strftime formats yielding 2-digit years
251 C ObjC Var(warn_format_zero_length) Warning
252 Warn about zero-length formats
255 C ObjC C++ ObjC++ Joined Warning
258 C C++ Var(warn_ignored_qualifiers) Init(-1) Warning
259 Warn whenever type qualifiers are ignored.
262 C ObjC C++ ObjC++ Var(warn_init_self) Warning
263 Warn about variables which are initialized to themselves
266 C ObjC Var(warn_implicit) Init(-1) Warning
267 Warn about implicit declarations
269 Wimplicit-function-declaration
270 C ObjC Var(warn_implicit_function_declaration) Init(-1) Warning
271 Warn about implicit function declarations
274 C ObjC Var(warn_implicit_int) Init(-1) Warning
275 Warn when a declaration does not specify a type
278 C ObjC C++ ObjC++ Undocumented
281 C ObjC C++ ObjC++ Var(warn_int_to_pointer_cast) Init(1) Warning
282 Warn when there is a cast to a pointer from an integer of a different size
285 C++ ObjC++ Var(warn_invalid_offsetof) Init(1) Warning
286 Warn about invalid uses of the \"offsetof\" macro
289 C ObjC C++ ObjC++ Warning
290 Warn about PCH files that are found but not used
293 C ObjC Var(warn_jump_misses_init) Init(-1) Warning
294 Warn when a jump misses a variable initialization
297 C ObjC C++ ObjC++ Var(warn_logical_op) Init(0) Warning
298 Warn when a logical operator is suspiciously always evaluating to true or false
301 C ObjC C++ ObjC++ Var(warn_long_long) Init(-1) Warning
302 Do not warn about using \"long long\" when -pedantic
305 C ObjC C++ ObjC++ Var(warn_main) Init(-1) Warning
306 Warn about suspicious declarations of \"main\"
309 C ObjC C++ ObjC++ Var(warn_missing_braces) Warning
310 Warn about possibly missing braces around initializers
312 Wmissing-declarations
313 C ObjC C++ ObjC++ Var(warn_missing_declarations) Warning
314 Warn about global functions without previous declarations
316 Wmissing-field-initializers
317 C ObjC C++ ObjC++ Var(warn_missing_field_initializers) Init(-1) Warning
318 Warn about missing fields in struct initializers
320 Wmissing-format-attribute
321 C ObjC C++ ObjC++ Var(warn_missing_format_attribute) Warning
322 Warn about functions which might be candidates for format attributes
324 Wmissing-include-dirs
325 C ObjC C++ ObjC++ Warning
326 Warn about user-specified include directories that do not exist
328 Wmissing-parameter-type
329 C ObjC Var(warn_missing_parameter_type) Init(-1) Warning
330 Warn about function parameters declared without a type specifier in K&R-style functions
333 C ObjC Var(warn_missing_prototypes) Warning
334 Warn about global functions without prototypes
337 C ObjC C++ ObjC++ Warning
338 Warn about use of multi-character character constants
341 C ObjC Var(warn_nested_externs) Warning
342 Warn about \"extern\" declarations not at file scope
345 C++ ObjC++ Var(warn_nontemplate_friend) Init(1) Warning
346 Warn when non-templatized friend functions are declared within a template
349 C++ ObjC++ Var(warn_nonvdtor) Warning
350 Warn about non-virtual destructors
353 C ObjC Var(warn_nonnull) Warning
354 Warn about NULL being passed to argument slots marked as requiring non-NULL
357 C ObjC C++ ObjC++ Joined Warning
358 -Wnormalized=<id|nfc|nfkc> Warn about non-normalised Unicode strings
361 C++ ObjC++ Var(warn_old_style_cast) Warning
362 Warn if a C-style cast is used in a program
364 Wold-style-declaration
365 C ObjC Var(warn_old_style_declaration) Init(-1) Warning
366 Warn for obsolescent usage in a declaration
368 Wold-style-definition
369 C ObjC Var(warn_old_style_definition) Warning
370 Warn if an old-style parameter definition is used
373 C ObjC C++ ObjC++ Var(warn_overlength_strings) Init(-1) Warning
374 Warn if a string is longer than the maximum portable length specified by the standard
377 C++ ObjC++ Var(warn_overloaded_virtual) Warning
378 Warn about overloaded virtual function names
381 C ObjC Var(warn_override_init) Init(-1) Warning
382 Warn about overriding initializers without side effects
384 Wpacked-bitfield-compat
385 C ObjC C++ ObjC++ Var(warn_packed_bitfield_compat) Init(-1) Warning
386 Warn about packed bit-fields whose offset changed in GCC 4.4
389 C ObjC C++ ObjC++ Var(warn_parentheses) Warning
390 Warn about possibly missing parentheses
393 C++ ObjC++ Var(warn_pmf2ptr) Init(1) Warning
394 Warn when converting the type of pointers to member functions
397 C ObjC C++ ObjC++ Var(warn_pointer_arith) Warning
398 Warn about function pointer arithmetic
401 C ObjC Var(warn_pointer_to_int_cast) Init(1) Warning
402 Warn when a pointer is cast to an integer of a different size
405 C ObjC C++ ObjC++ Var(warn_pragmas) Init(1) Warning
406 Warn about misuses of pragmas
409 ObjC ObjC++ Var(warn_protocol) Init(1) Warning
410 Warn if inherited methods are unimplemented
413 C ObjC C++ ObjC++ Var(warn_redundant_decls) Warning
414 Warn about multiple declarations of the same object
417 C++ ObjC++ Var(warn_reorder) Warning
418 Warn when the compiler reorders code
421 C ObjC C++ ObjC++ Var(warn_return_type) Warning
422 Warn whenever a function's return type defaults to \"int\" (C), or about inconsistent return types (C++)
425 ObjC ObjC++ Var(warn_selector) Warning
426 Warn if a selector has multiple methods
429 C ObjC C++ ObjC++ Var(warn_sequence_point) Warning
430 Warn about possible violations of sequence point rules
433 C ObjC C++ ObjC++ Var(warn_sign_compare) Init(-1) Warning
434 Warn about signed-unsigned comparisons
437 C++ ObjC++ Var(warn_sign_promo) Warning
438 Warn when overload promotes from unsigned to signed
440 Wstrict-null-sentinel
442 Warn about uncasted NULL used as sentinel
445 C ObjC Var(warn_strict_prototypes) Warning
446 Warn about unprototyped function declarations
448 Wstrict-selector-match
449 ObjC ObjC++ Var(warn_strict_selector_match) Warning
450 Warn if type signatures of candidate methods do not match exactly
453 C C++ Var(warn_sync_nand) Init(1) Warning
454 Warn when __sync_fetch_and_nand and __sync_nand_and_fetch built-in functions are used
457 C++ ObjC++ Var(warn_synth) Warning
458 Deprecated. This switch has no effect
461 C ObjC C++ ObjC++ Warning
462 ; Documented in common.opt
465 C ObjC Var(warn_traditional) Warning
466 Warn about features not present in traditional C
468 Wtraditional-conversion
469 C ObjC Var(warn_traditional_conversion) Warning
470 Warn of prototypes causing type conversions different from what would happen in the absence of prototype
473 C ObjC C++ ObjC++ Warning
474 Warn if trigraphs are encountered that might affect the meaning of the program
477 ObjC ObjC++ Var(warn_undeclared_selector) Warning
478 Warn about @selector()s without previously declared methods
481 C ObjC C++ ObjC++ Warning
482 Warn if an undefined macro is used in an #if directive
485 C ObjC C++ ObjC++ Warning
486 Warn about unrecognized pragmas
488 Wunsuffixed-float-constants
489 C ObjC Var(warn_unsuffixed_float_constants) Warning
490 Warn about unsuffixed float constants
493 C ObjC C++ ObjC++ Warning
494 Warn about macros defined in the main file that are not used
497 C ObjC C++ ObjC++ Var(warn_unused_result) Init(1) Warning
498 Warn if a caller of a function, marked with attribute warn_unused_result, does not use its return value
501 C ObjC C++ ObjC++ Warning
502 Do not warn about using variadic macros when -pedantic
505 C ObjC C++ ObjC++ Var(warn_vla) Init(-1) Warning
506 Warn if a variable length array is used
508 Wvolatile-register-var
509 C ObjC C++ ObjC++ Var(warn_volatile_register_var) Warning
510 Warn when a register variable is declared volatile
513 C ObjC C++ ObjC++ Var(warn_write_strings) Warning
514 In C++, nonzero means warn about deprecated conversion from string literals to `char *'. In C, similar warning, except that the conversion is of course not deprecated by the ISO C standard.
517 C ObjC Var(warn_pointer_sign) Init(-1) Warning
518 Warn when a pointer differs in signedness in an assignment
522 A synonym for -std=c89 (for C) or -std=c++98 (for C++)
525 C ObjC C++ ObjC++ Joined
526 ; Documented in common.opt. FIXME - what about -dI, -dD, -dN and -dD?
530 Enforce class member access control semantics
535 falt-external-templates
537 Change when template instances are emitted
541 Recognize the \"asm\" keyword
545 Recognize built-in functions
548 C ObjC C++ ObjC++ Joined
552 Check the return value of new
556 Allow the arguments of the '?' operator to have different types
560 Reduce the size of object files
562 fconstant-string-class=
564 -fconst-string-class=<name> Use class <name> for constant strings
567 C++ ObjC++ Var(flag_deduce_init_list) Init(1)
568 -fno-deduce-init-list disable deduction of std::initializer_list for a template type parameter from a brace-enclosed initializer-list
572 Inline member functions by default
576 Preprocess directives only.
578 fdollars-in-identifiers
580 Permit '$' as an identifier character
587 Generate code to check exception specifications
593 C ObjC C++ ObjC++ Joined RejectNegative
594 -fexec-charset=<cset> Convert all strings and character constants to character set <cset>
596 fextended-identifiers
598 Permit universal character names (\\u and \\U) in identifiers
601 C ObjC C++ ObjC++ Joined RejectNegative
602 -finput-charset=<cset> Specify the default character set for source files
610 Scope of for-init-statement variables is local to the loop
614 Do not assume that standard C libraries and \"main\" exist
618 Recognize GNU-defined keywords
622 Generate code for GNU runtime environment
625 C ObjC Var(flag_gnu89_inline) Init(-1)
626 Use traditional GNU semantics for inline functions
632 C++ ObjC++ Optimization
639 Assume normal C execution environment
643 Enable support for huge objects
647 Export functions even if they can be inlined
649 fimplicit-inline-templates
651 Emit implicit instantiations of inline templates
655 Emit implicit instantiations of templates
658 C++ ObjC++ Var(flag_friend_injection)
659 Inject friend functions into enclosing namespace
664 flax-vector-conversions
666 Allow implicit conversions between vectors with differing numbers of subparts and/or differing element types.
670 Don't warn about uses of Microsoft extensions
672 fname-mangling-version-
680 Generate code for NeXT (Apple Mac OS X) runtime environment
684 Assume that receivers of Objective-C messages may be nil
692 ; Generate special '- .cxx_construct' and '- .cxx_destruct' methods
693 ; to initialize any non-POD ivars in Objective-C++ classes.
694 fobjc-call-cxx-cdtors
695 ObjC++ Var(flag_objc_call_cxx_cdtors)
696 Generate special Objective-C methods to initialize/destroy non-POD C++ ivars, if needed
698 fobjc-direct-dispatch
699 ObjC ObjC++ Var(flag_objc_direct_dispatch)
700 Allow fast jumps to the message dispatcher
702 ; Nonzero means that we will allow new ObjC exception syntax (@throw,
703 ; @try, etc.) in source code.
705 ObjC ObjC++ Var(flag_objc_exceptions)
706 Enable Objective-C exception and synchronization syntax
709 ObjC ObjC++ Var(flag_objc_gc)
710 Enable garbage collection (GC) in Objective-C/Objective-C++ programs
712 ; Nonzero means that we generate NeXT setjmp based exceptions.
713 fobjc-sjlj-exceptions
714 ObjC ObjC++ Var(flag_objc_sjlj_exceptions) Init(-1)
715 Enable Objective-C setjmp exception handling runtime
718 C ObjC C++ ObjC++ Var(flag_openmp)
719 Enable OpenMP (implies -frecursive in Fortran)
723 Recognize C++ keywords like \"compl\" and \"xor\"
727 Enable optional diagnostics
734 Look for and use PCH files even when preprocessing
738 Downgrade conformance errors to warnings
742 Treat the input file as already preprocessed
746 -fno-pretty-templates Do not pretty-print template specializations as the template signature followed by the arguments
748 freplace-objc-classes
750 Used in Fix-and-Continue mode to indicate that object files may be swapped in at runtime
754 Enable automatic template instantiation
757 C++ ObjC++ Optimization
758 Generate run time type descriptor information
761 C ObjC C++ ObjC++ Optimization
762 Use the same size for double as for float
765 C ObjC C++ ObjC++ Optimization
766 Use the narrowest integer type possible for enumeration types
769 C ObjC C++ ObjC++ Optimization
770 Force the underlying type for \"wchar_t\" to be \"unsigned short\"
774 When \"signed\" or \"unsigned\" is not given make the bitfield signed
777 C ObjC C++ ObjC++ LTO
778 Make \"char\" signed by default
785 Display statistics accumulated during compilation
788 C++ ObjC++ Optimization Var(flag_strict_enums)
789 Assume that values of enumeration type are always within the minimum range of that type
795 C ObjC C++ ObjC++ Joined RejectNegative UInteger
796 -ftabstop=<number> Distance between tab stops for column reporting
799 C++ ObjC++ Joined RejectNegative UInteger Undocumented
802 C++ ObjC++ Joined RejectNegative UInteger
803 -ftemplate-depth=<number> Specify maximum template instantiation depth
809 C++ ObjC++ Optimization
810 -fno-threadsafe-statics Do not generate thread-safe code for initializing local statics
814 When \"signed\" or \"unsigned\" is not given make the bitfield unsigned
817 C ObjC C++ ObjC++ LTO
818 Make \"char\" unsigned by default
822 Use __cxa_atexit to register destructors
824 fuse-cxa-get-exception-ptr
826 Use __cxa_get_exception_ptr in exception handling
828 fvisibility-inlines-hidden
830 Marks all inlined methods as having hidden visibility
832 fvisibility-ms-compat
833 C++ ObjC++ Var(flag_visibility_ms_compat)
834 Changes visibility to match Microsoft Visual Studio by default
838 Discard unused virtual functions
842 Implement vtables using thunks
846 Emit common-like symbols as weak symbols
849 C ObjC C++ ObjC++ Joined RejectNegative
850 -fwide-exec-charset=<cset> Convert all wide strings and character constants to character set <cset>
854 Generate a #line directive pointing at the current working directory
858 Emit cross referencing information
862 Generate lazy class lookup (via objc_getClass()) for use in Zero-Link mode
866 Dump declarations to a .decl file
868 femit-struct-debug-baseonly
870 -femit-struct-debug-baseonly Aggressive reduced debug info for structs
872 femit-struct-debug-reduced
874 -femit-struct-debug-reduced Conservative reduced debug info for structs
876 femit-struct-debug-detailed=
877 C ObjC C++ ObjC++ Joined
878 -femit-struct-debug-detailed=<spec-list> Detailed reduced debug info for structs
881 C ObjC C++ ObjC++ Joined Separate
882 -idirafter <dir> Add <dir> to the end of the system include path
885 C ObjC C++ ObjC++ Joined Separate
886 -imacros <file> Accept definition of macros in <file>
889 C ObjC C++ ObjC++ Joined Separate
890 -imultilib <dir> Set <dir> to be the multilib include subdirectory
893 C ObjC C++ ObjC++ Joined Separate
894 -include <file> Include the contents of <file> before other files
897 C ObjC C++ ObjC++ Joined Separate
898 -iprefix <path> Specify <path> as a prefix for next two options
901 C ObjC C++ ObjC++ Joined Separate
902 -isysroot <dir> Set <dir> to be the system root directory
905 C ObjC C++ ObjC++ Joined Separate
906 -isystem <dir> Add <dir> to the start of the system include path
909 C ObjC C++ ObjC++ Joined Separate
910 -iquote <dir> Add <dir> to the end of the quote include path
913 C ObjC C++ ObjC++ Joined Separate
914 -iwithprefix <dir> Add <dir> to the end of the system include path
917 C ObjC C++ ObjC++ Joined Separate
918 -iwithprefixbefore <dir> Add <dir> to the end of the main include path
924 C ObjC C++ ObjC++ Undocumented
928 Do not search standard system include directories (those specified with -isystem will still be used)
932 Do not search standard system include directories for C++
935 C ObjC C++ ObjC++ Joined Separate
936 ; Documented in common.opt
940 ; Documented in common.opt
944 ; Documented in common.opt
946 print-objc-runtime-info
948 Generate C header of platform-specific features
952 Print a checksum of the executable for PCH validity checking, and stop
956 Remap file names when including files
960 Conform to the ISO 1998 C++ standard
964 Conform to the ISO 1998 C++ standard, with extensions that are likely to
965 become a part of the upcoming ISO C++ standard, dubbed C++0x. Note that the
966 extensions enabled by this mode are experimental and may be removed in
967 future releases of GCC.
971 Conform to the ISO 201X C standard draft (experimental and incomplete support)
975 Conform to the ISO 1990 C standard
979 Conform to the ISO 1990 C standard
983 Conform to the ISO 1999 C standard
987 Deprecated in favor of -std=c99
991 Conform to the ISO 1998 C++ standard with GNU extensions
995 Conform to the ISO 1998 C++ standard, with GNU extensions and
996 extensions that are likely to become a part of the upcoming ISO C++
997 standard, dubbed C++0x. Note that the extensions enabled by this mode
998 are experimental and may be removed in future releases of GCC.
1002 Conform to the ISO 201X C standard draft with GNU extensions (experimental and incomplete support)
1006 Conform to the ISO 1990 C standard with GNU extensions
1010 Conform to the ISO 1990 C standard with GNU extensions
1014 Conform to the ISO 1999 C standard with GNU extensions
1018 Deprecated in favor of -std=gnu99
1022 Conform to the ISO 1990 C standard
1026 Conform to the ISO 1990 C standard as amended in 1994
1030 Conform to the ISO 1999 C standard
1034 Deprecated in favor of -std=iso9899:1999
1038 Enable traditional preprocessing
1042 -trigraphs Support ISO C trigraphs
1046 Do not predefine system-specific and GCC-specific macros
1049 Common C ObjC C++ ObjC++
1050 Enable verbose output
1054 ; Documented in common.opt
1056 ; This comment is to ensure we retain the blank line above.