1 ; Options for the C, ObjC, C++ and ObjC++ front ends.
2 ; Copyright (C) 2003-2024 Free Software Foundation, Inc.
4 ; This file is part of GCC.
6 ; GCC is free software; you can redistribute it and/or modify it under
7 ; the terms of the GNU General Public License as published by the Free
8 ; Software Foundation; either version 3, or (at your option) any later
11 ; GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 ; WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 ; FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 ; You should have received a copy of the GNU General Public License
17 ; along with GCC; see the file COPYING3. If not see
18 ; <http://www.gnu.org/licenses/>.
20 ; See the GCC internals manual for a description of this file's format.
22 ; Please try to keep this file in ASCII collating order.
37 C ObjC C++ ObjC++ Warning Alias(Wall)
40 C ObjC C++ ObjC++ Alias(ansi)
43 C ObjC C++ ObjC++ Separate Alias(A) MissingArgError(assertion missing after %qs)
46 C ObjC C++ ObjC++ Joined Alias(A) MissingArgError(assertion missing after %qs)
49 C ObjC C++ ObjC++ Alias(C)
52 C ObjC C++ ObjC++ Alias(CC)
55 C ObjC C++ ObjC++ Separate Alias(D) MissingArgError(macro name missing after %qs)
58 C ObjC C++ ObjC++ Joined Alias(D) MissingArgError(macro name missing after %qs)
61 C ObjC C++ ObjC++ Alias(M)
64 C ObjC C++ ObjC++ Separate Alias(d)
67 C ObjC C++ ObjC++ Joined Alias(d)
70 C ObjC C++ ObjC++ Separate Alias(imacros) MissingArgError(missing filename after %qs)
73 C ObjC C++ ObjC++ Joined Alias(imacros) MissingArgError(missing filename after %qs)
76 C ObjC C++ ObjC++ Separate Alias(include) MissingArgError(missing filename after %qs)
79 C ObjC C++ ObjC++ Joined Alias(include) MissingArgError(missing filename after %qs)
82 C ObjC C++ ObjC++ Alias(I, -)
85 C ObjC C++ ObjC++ Separate Alias(I) MissingArgError(missing path after %qs)
88 C ObjC C++ ObjC++ Joined Alias(I) MissingArgError(missing path after %qs)
90 -include-directory-after
91 C ObjC C++ ObjC++ Separate Alias(idirafter) MissingArgError(missing path after %qs)
93 -include-directory-after=
94 C ObjC C++ ObjC++ Joined Alias(idirafter) MissingArgError(missing path after %qs)
97 C ObjC C++ ObjC++ Separate Alias(iprefix)
100 C ObjC C++ ObjC++ JoinedOrMissing Alias(iprefix)
103 C ObjC C++ ObjC++ Separate Alias(iwithprefix)
105 -include-with-prefix=
106 C ObjC C++ ObjC++ JoinedOrMissing Alias(iwithprefix)
108 -include-with-prefix-after
109 C ObjC C++ ObjC++ Separate Alias(iwithprefix)
111 -include-with-prefix-after=
112 C ObjC C++ ObjC++ JoinedOrMissing Alias(iwithprefix)
114 -include-with-prefix-before
115 C ObjC C++ ObjC++ Separate Alias(iwithprefixbefore)
117 -include-with-prefix-before=
118 C ObjC C++ ObjC++ JoinedOrMissing Alias(iwithprefixbefore)
121 Driver Alias(no-integrated-cpp)
124 C ObjC C++ ObjC++ Alias(P)
126 -no-standard-includes
127 C ObjC C++ ObjC++ Alias(nostdinc)
130 C ObjC C++ ObjC++ Alias(w)
133 C ObjC C++ ObjC++ Separate Alias(o)
136 C ObjC C++ ObjC++ Joined Alias(o)
139 C ObjC C++ ObjC++ Separate
142 C ObjC C++ ObjC++ Alias(pedantic)
145 C ObjC C++ ObjC++ Undocumented Alias(E)
147 -print-missing-file-dependencies
148 C ObjC C++ ObjC++ Alias(MG)
151 C ObjC C++ ObjC++ Alias(H)
154 Driver Alias(traditional)
157 C ObjC C++ ObjC++ Alias(traditional-cpp)
160 C ObjC C++ ObjC++ Alias(trigraphs)
163 C ObjC C++ ObjC++ Separate Alias(U) MissingArgError(macro name missing after %qs)
166 C ObjC C++ ObjC++ Joined Alias(U) MissingArgError(macro name missing after %qs)
169 C ObjC C++ ObjC++ Alias(MM)
172 Common C ObjC C++ ObjC++ Alias(v)
175 C ObjC C++ ObjC++ NoDriverArg Separate Alias(MD) MissingArgError(missing filename after %qs)
177 -write-user-dependencies
178 C ObjC C++ ObjC++ NoDriverArg Separate Alias(MMD) MissingArgError(missing filename after %qs)
181 C ObjC C++ ObjC++ Joined Separate MissingArgError(assertion missing after %qs)
182 -A<question>=<answer> Assert the <answer> to <question>. Putting '-' before <question> disables the <answer> to <question>.
186 Do not discard comments.
190 Do not discard comments in macro expansions.
193 C ObjC C++ ObjC++ Joined Separate MissingArgError(macro name missing after %qs)
194 -D<macro>[=<val>] Define a <macro> with <val> as its value. If just <macro> is given, <val> is taken to be 1.
197 C ObjC C++ ObjC++ Undocumented Var(flag_preprocess_only)
200 Driver C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
201 -F <dir> Add <dir> to the end of the main framework include path.
204 C Var(flag_gimple) Init(0)
205 Enable parsing GIMPLE.
209 Print the name of header files as they are used.
212 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
213 -I <dir> Add <dir> to the end of the main include path.
217 Generate make dependencies.
220 C ObjC C++ ObjC++ NoDriverArg Separate MissingArgError(missing filename after %qs)
221 Generate make dependencies and compile.
224 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing filename after %qs)
225 -MF <file> Write dependency output to the given file.
229 Treat missing header files as generated files.
233 Like -M but ignore system header files.
236 C ObjC C++ ObjC++ NoDriverArg Separate MissingArgError(missing filename after %qs)
237 Like -MD but ignore system header files.
241 Generate C++ Module dependency information.
249 Generate phony targets for all headers.
252 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing makefile target after %qs)
253 -MQ <target> Add a target that may require quoting.
256 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing makefile target after %qs)
257 -MT <target> Add a target that does not require quoting.
260 C ObjC C++ ObjC++ NoDriverArg Joined MissingArgError(missing format after %qs)
261 Structured format for output dependency information. Supported (\"p1689r5\").
264 C ObjC C++ ObjC++ NoDriverArg Joined MissingArgError(missing output path after %qs)
265 File for output dependency information.
268 C ObjC C++ ObjC++ NoDriverArg Joined MissingArgError(missing path after %qs)
269 -fdeps-target=obj.o Output file for the compile step.
273 Do not generate #line directives.
276 C ObjC C++ ObjC++ Joined Separate MissingArgError(macro name missing after %qs)
277 -U<macro> Undefine <macro>.
280 C ObjC C++ ObjC++ LTO Var(warn_nsobject_attribute) Warning Init(1)
281 Warn if the NSObject attribute is applied to a non-typedef.
284 C ObjC C++ ObjC++ LTO Var(warn_abi) Warning
285 Warn about things that will change when compiling with an ABI-compliant compiler.
288 C ObjC C++ ObjC++ LTO Joined RejectNegative UInteger Warning
289 Warn about things that change between the current -fabi-version and the specified version.
292 C++ ObjC++ Var(warn_abi_tag) Warning
293 Warn if a subobject has an abi_tag attribute that the complete object type does not have.
296 C ObjC C++ ObjC++ LTO Var(warn_psabi) Init(1) Warning Undocumented LangEnabledBy(C ObjC C++ ObjC++,Wabi)
299 C ObjC Var(warn_absolute_value) Warning EnabledBy(Wextra)
300 Warn on suspicious calls of standard functions computing absolute values.
303 C ObjC C++ ObjC++ Var(warn_address) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
304 Warn about suspicious uses of memory addresses.
306 Waddress-of-packed-member
307 C ObjC C++ ObjC++ Var(warn_address_of_packed_member) Init(1) Warning
308 Warn when the address of packed member of struct or union is taken.
311 Name(warn_aligned_new_level) Type(int) UnknownError(argument %qs to %<-Waligned-new%> not recognized)
314 Enum(warn_aligned_new_level) String(none) Value(0)
317 Enum(warn_aligned_new_level) String(global) Value(1)
320 Enum(warn_aligned_new_level) String(all) Value(2)
323 C++ ObjC++ Alias(Waligned-new=,global,none)
324 Warn about 'new' of type with extended alignment without -faligned-new.
327 C++ ObjC++ Var(warn_aligned_new) Enum(warn_aligned_new_level) Joined RejectNegative Warning LangEnabledBy(C++ ObjC++,Wall,1,0)
328 -Waligned-new=[none|global|all] Warn even if 'new' uses a class member allocation function.
331 C ObjC C++ ObjC++ Warning
332 Enable most warning messages.
335 C ObjC C++ ObjC++ Var(warn_alloca) Warning
336 Warn on any use of alloca.
339 C ObjC C++ ObjC++ Var(warn_alloc_size) Warning LangEnabledBy(C ObjC C++ ObjC++, Wextra)
340 Warn when allocating insufficient storage for the target type of the assigned pointer.
342 Walloc-size-larger-than=
343 C ObjC C++ LTO ObjC++ Var(warn_alloc_size_limit) Joined Host_Wide_Int ByteSize Warning Init(HOST_WIDE_INT_MAX)
344 -Walloc-size-larger-than=<bytes> Warn for calls to allocation functions that
345 attempt to allocate objects larger than the specified number of bytes.
347 Wno-alloc-size-larger-than
348 C ObjC C++ LTO ObjC++ Alias(Walloc-size-larger-than=,18446744073709551615EiB,none) Warning
349 Disable Walloc-size-larger-than= warning. Equivalent to Walloc-size-larger-than=<SIZE_MAX> or larger.
352 C ObjC C++ ObjC++ Var(warn_alloc_zero) Warning
353 Warn for calls to allocation functions that specify zero bytes.
356 C ObjC C++ LTO ObjC++ Var(warn_alloca_limit) Warning Joined Host_Wide_Int ByteSize Init(HOST_WIDE_INT_MAX)
357 -Walloca-larger-than=<number> Warn on unbounded uses of
358 alloca, and on bounded uses of alloca whose bound can be larger than
361 Wno-alloca-larger-than
362 C ObjC C++ LTO ObjC++ Alias(Walloca-larger-than=,18446744073709551615EiB,none) Warning
363 Disable Walloca-larger-than= warning. Equivalent to Walloca-larger-than=<SIZE_MAX> or larger.
366 C ObjC C++ ObjC++ Var(warn_arith_conv) Warning
367 Warn if conversion of the result of arithmetic might change the value even though converting the operands cannot.
370 LangEnabledBy(C ObjC C++ LTO ObjC++,Wall,1,0)
374 C ObjC C++ ObjC++ Var(warn_array_compare) Warning LangEnabledBy(C ObjC C++ ObjC++, Wall)
375 Warn about comparisons between two operands of array type.
378 C ObjC C++ ObjC++ Warning Alias(Warray-parameter=, 2, 0)
379 Warn about mismatched declarations of array parameters and unsafe accesses to them.
382 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_array_parameter) IntegerRange(0, 2) LangEnabledBy(C ObjC C++ ObjC++,Wall, 2, 0) Warning
383 Warn about mismatched declarations of array parameters and unsafe accesses to them.
386 ObjC ObjC++ Var(warn_assign_intercept) Warning
387 Warn whenever an Objective-C assignment is being intercepted by the garbage collector.
390 C ObjC Var(warn_bad_function_cast) Warning
391 Warn about casting functions to incompatible types.
394 C ObjC C++ ObjC++ Warning Alias(Wbidi-chars=,any,none)
398 C ObjC C++ ObjC++ RejectNegative Joined Warning CPP(cpp_warn_bidirectional) CppReason(CPP_W_BIDIRECTIONAL) Var(warn_bidirectional) Init(bidirectional_unpaired) Enum(cpp_bidirectional_level) EnumSet
399 -Wbidi-chars=[none|unpaired|any|ucn] Warn about UTF-8 bidirectional control characters.
401 ; Required for these enum values.
406 Name(cpp_bidirectional_level) Type(int) UnknownError(argument %qs to %<-Wbidi-chars%> not recognized)
409 Enum(cpp_bidirectional_level) String(none) Value(bidirectional_none) Set(1)
412 Enum(cpp_bidirectional_level) String(unpaired) Value(bidirectional_unpaired) Set(1)
415 Enum(cpp_bidirectional_level) String(any) Value(bidirectional_any) Set(1)
418 Enum(cpp_bidirectional_level) String(ucn) Value(bidirectional_ucn) Set(2)
421 C ObjC C++ ObjC++ Var(warn_bool_compare) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
422 Warn about boolean expression compared with an integer value different from true/false.
425 C ObjC C++ ObjC++ Var(warn_bool_op) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
426 Warn about certain operations on boolean expressions.
428 Wbuiltin-declaration-mismatch
429 C ObjC C++ ObjC++ Var(warn_builtin_declaration_mismatch) Init(1) Warning
430 Warn when a built-in function is declared with the wrong signature.
432 Wbuiltin-macro-redefined
433 C ObjC C++ ObjC++ CPP(warn_builtin_macro_redefined) CppReason(CPP_W_BUILTIN_MACRO_REDEFINED) Var(cpp_warn_builtin_macro_redefined) Init(1) Warning
434 Warn when a built-in preprocessor macro is undefined or redefined.
437 C ObjC CPP(cpp_warn_c11_c23_compat) CppReason(CPP_W_C11_C23_COMPAT) Var(warn_c11_c23_compat) Init(-1) Warning
438 Warn about features not present in ISO C11, but present in ISO C23.
441 C ObjC Alias(Wc11-c23-compat)
442 Deprecated in favor of -Wc11-c23-compat.
445 C ObjC CPP(cpp_warn_c90_c99_compat) CppReason(CPP_W_C90_C99_COMPAT) Var(warn_c90_c99_compat) Init(-1) Warning
446 Warn about features not present in ISO C90, but present in ISO C99.
449 C ObjC Var(warn_c99_c11_compat) Init(-1) Warning
450 Warn about features not present in ISO C99, but present in ISO C11.
453 C ObjC Var(warn_cxx_compat) CPP(warn_cxx_operator_names) CppReason(CPP_W_CXX_OPERATOR_NAMES) Init(0) Warning
454 Warn about C constructs that are not in the common subset of C and C++.
457 C++ ObjC++ Warning Alias(Wc++11-compat) Undocumented
460 C++ ObjC++ Var(warn_cxx11_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx11_compat) CppReason(CPP_W_CXX11_COMPAT)
461 Warn about C++ constructs whose meaning differs between ISO C++ 1998 and ISO C++ 2011.
464 C++ ObjC++ Var(warn_cxx14_compat) Warning LangEnabledBy(C++ ObjC++,Wall)
465 Warn about C++ constructs whose meaning differs between ISO C++ 2011 and ISO C++ 2014.
468 C++ ObjC++ Warning Alias(Wc++17-compat) Undocumented
471 C++ ObjC++ Var(warn_cxx17_compat) Warning LangEnabledBy(C++ ObjC++,Wall)
472 Warn about C++ constructs whose meaning differs between ISO C++ 2014 and ISO C++ 2017.
475 C++ ObjC++ Warning Alias(Wc++20-compat) Undocumented
478 C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx20_compat) CppReason(CPP_W_CXX20_COMPAT)
479 Warn about C++ constructs whose meaning differs between ISO C++ 2017 and ISO C++ 2020.
482 C++ ObjC++ Var(warn_cxx11_extensions) Warning Init(1)
483 Warn about C++11 constructs in code compiled with an older standard.
486 C++ ObjC++ Var(warn_cxx14_extensions) Warning Init(1)
487 Warn about C++14 constructs in code compiled with an older standard.
490 C++ ObjC++ Var(warn_cxx17_extensions) Warning Init(1)
491 Warn about C++17 constructs in code compiled with an older standard.
494 C++ ObjC++ Var(warn_cxx20_extensions) Warning Init(1)
495 Warn about C++20 constructs in code compiled with an older standard.
498 C++ ObjC++ Var(warn_cxx23_extensions) Warning Init(1)
499 Warn about C++23 constructs in code compiled with an older standard.
502 C++ ObjC++ Var(warn_cxx26_extensions) Warning Init(1)
503 Warn about C++26 constructs in code compiled with an older standard.
505 Wcalloc-transposed-args
506 C ObjC C++ ObjC++ Var(warn_calloc_transposed_args) Warning LangEnabledBy(C ObjC C++ ObjC++,Wextra)
507 Warn about suspicious calls to calloc-like functions where sizeof expression is the earlier size argument and not the latter.
510 C ObjC C++ ObjC++ Var(warn_cast_function_type) Warning EnabledBy(Wextra)
511 Warn about casts between incompatible function types.
514 C ObjC C++ ObjC++ Var(warn_cast_qual) Warning
515 Warn about casts which discard qualifiers.
518 C++ ObjC++ Var(warn_cast_user_defined) Warning Init(1)
519 Warn about a cast to reference type that does not use a related user-defined conversion function.
522 C++ ObjC++ Warning Alias(Wcatch-value=, 1, 0)
523 Warn about catch handlers of non-reference type.
526 C++ ObjC++ Var(warn_catch_value) Warning Joined RejectNegative UInteger LangEnabledBy(C++ ObjC++,Wall, 1, 0) IntegerRange(0, 3)
527 Warn about catch handlers of non-reference type.
530 C++ ObjC++ Var(warn_changes_meaning) Warning Init(1)
531 Complain about a name being declared as a class member after a previous use of the same name.
534 C ObjC C++ ObjC++ Var(warn_char_subscripts) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
535 Warn about subscripts whose type is \"char\".
538 C ObjC C++ ObjC++ Warning WarnRemoved
539 Removed in GCC 9. This switch has no effect.
542 C++ ObjC++ Var(warn_class_conversion) Init(1) Warning
543 Warn when a conversion function will never be called due to the type it converts to.
546 C++ ObjC++ Var(warn_class_memaccess) Warning LangEnabledBy(C++ ObjC++, Wall)
547 Warn for unsafe raw memory writes to objects of class types.
550 C ObjC C++ ObjC++ Var(warn_clobbered) Warning EnabledBy(Wextra)
551 Warn about variables that might be changed by \"longjmp\" or \"vfork\".
554 C++ ObjC++ Var(warn_comma_subscript) Warning
555 Warn about uses of a comma operator within a subscripting expression.
558 C ObjC C++ ObjC++ CPP(warn_comments) CppReason(CPP_W_COMMENTS) Var(cpp_warn_comment) Init(0) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
559 Warn about possibly nested block comments, and C++ comments spanning more than one physical line.
562 C ObjC C++ ObjC++ Warning Alias(Wcomment)
563 Synonym for -Wcomment.
565 Wconditionally-supported
566 C++ ObjC++ Var(warn_conditionally_supported) Warning
567 Warn for conditionally-supported constructs.
570 C ObjC C++ ObjC++ Var(warn_conversion) Warning
571 Warn for implicit type conversions that may change a value.
574 C++ ObjC++ Var(warn_conversion_null) Init(1) Warning
575 Warn for converting NULL from/to a non-pointer type.
578 C ObjC C++ ObjC++ CppReason(CPP_W_WARNING_DIRECTIVE)
579 ; Documented in common.opt
581 Wctad-maybe-unsupported
582 C++ ObjC++ Var(warn_ctad_maybe_unsupported) Warning
583 Warn when performing class template argument deduction on a type with no
587 C++ ObjC++ Var(warn_ctor_dtor_privacy) Warning
588 Warn when all constructors and destructors are private.
591 C ObjC C++ ObjC++ Var(warn_dangling_else) Warning LangEnabledBy(C ObjC C++ ObjC++,Wparentheses)
592 Warn about dangling else.
595 C ObjC C++ LTO ObjC++ Alias(Wdangling-pointer=, 2, 0) Warning
596 Warn for uses of pointers to auto variables whose lifetime has ended.
599 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_dangling_pointer) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall, 2, 0) IntegerRange(0, 2)
600 Warn for uses of pointers to auto variables whose lifetime has ended.
603 C++ ObjC++ Var(warn_dangling_reference) Warning LangEnabledBy(C++ ObjC++, Wall)
604 Warn when a reference is bound to a temporary whose lifetime has ended.
607 C ObjC C++ ObjC++ CPP(warn_date_time) CppReason(CPP_W_DATE_TIME) Var(cpp_warn_date_time) Init(0) Warning
608 Warn about __TIME__, __DATE__ and __TIMESTAMP__ usage.
610 Wdeclaration-after-statement
611 C ObjC Var(warn_declaration_after_statement) Init(-1) Warning
612 Warn when a declaration is found after a statement.
614 Wdeclaration-missing-parameter-type
615 C ObjC Var(warn_declaration_missing_parameter) Warning Init(1)
616 Warn for missing parameter types in function declarations.
619 C++ ObjC++ Var(warn_delete_incomplete) Init(1) Warning
620 Warn when deleting a pointer to incomplete type.
622 Wdelete-non-virtual-dtor
623 C++ ObjC++ Var(warn_delnonvdtor) Warning LangEnabledBy(C++ ObjC++,Wall || Weffc++)
624 Warn about deleting polymorphic objects with non-virtual destructors.
627 C C++ ObjC ObjC++ CPP(cpp_warn_deprecated) CppReason(CPP_W_DEPRECATED)
628 ; Documented in common.opt
631 C++ ObjC++ Var(warn_deprecated_copy) Warning LangEnabledBy(C++ ObjC++, Wextra)
632 Mark implicitly-declared copy operations as deprecated if the class has a
633 user-provided copy operation.
635 Wdeprecated-copy-dtor
636 C++ ObjC++ Var(warn_deprecated_copy, 2) Warning
637 Mark implicitly-declared copy operations as deprecated if the class has a
638 user-provided copy operation or destructor.
640 Wdeprecated-enum-enum-conversion
641 C++ ObjC++ Var(warn_deprecated_enum_enum_conv) Warning
642 Warn about deprecated arithmetic conversions on operands of enumeration types.
644 Wdeprecated-enum-float-conversion
645 C++ ObjC++ Var(warn_deprecated_enum_float_conv) Warning
646 Warn about deprecated arithmetic conversions on operands where one is of enumeration
647 type and the other is of a floating-point type.
650 C ObjC Var(warn_designated_init) Init(1) Warning
651 Warn about positional initialization of structs requiring designated initializers.
653 Wdiscarded-array-qualifiers
654 C ObjC Var(warn_discarded_array_qualifiers) Init(1) Warning
655 Warn if qualifiers on arrays which are pointer targets are discarded.
657 Wdiscarded-qualifiers
658 C ObjC Var(warn_discarded_qualifiers) Init(1) Warning
659 Warn if type qualifiers on pointers are discarded.
662 C ObjC C++ ObjC++ Var(warn_div_by_zero) Init(1) Warning
663 Warn about compile-time integer division by zero.
666 C ObjC C++ ObjC++ Var(warn_double_promotion) Warning
667 Warn about implicit conversions from \"float\" to \"double\".
669 Wduplicate-decl-specifier
670 C ObjC Var(warn_duplicate_decl_specifier) Warning LangEnabledBy(C ObjC,Wall)
671 Warn when a declaration has duplicate const, volatile, restrict or _Atomic specifier.
674 C ObjC C++ ObjC++ Var(warn_duplicated_branches) Init(0) Warning
675 Warn about duplicated branches in if-else statements.
678 C ObjC C++ ObjC++ Var(warn_duplicated_cond) Init(0) Warning
679 Warn about duplicated conditions in an if-else-if chain.
682 C++ ObjC++ Var(warn_ecpp) Warning
683 Warn about violations of Effective C++ style rules.
685 Welaborated-enum-base
686 C++ ObjC++ Var(warn_elaborated_enum_base) Warning Init(1)
687 Warn if an additional enum-base is used in an elaborated-type-specifier.
690 C ObjC C++ ObjC++ Var(warn_empty_body) Warning EnabledBy(Wextra)
691 Warn about an empty body in an if or else statement.
694 C ObjC C++ ObjC++ CPP(warn_endif_labels) CppReason(CPP_W_ENDIF_LABELS) Var(cpp_warn_endif_labels) Init(1) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic)
695 Warn about stray tokens after #else and #endif.
698 C ObjC C++ ObjC++ Var(warn_enum_compare) Init(-1) Warning LangEnabledBy(C ObjC,Wall || Wc++-compat)
699 Warn about comparison of different enum types.
702 C ObjC C++ ObjC++ Var(warn_enum_conversion) Init(0) Warning LangEnabledBy(C ObjC,Wextra)
703 Warn about implicit conversion of enum types.
706 C ObjC Var(warn_enum_int_mismatch) Warning LangEnabledBy(C ObjC,Wall || Wc++-compat)
707 Warn about enum/integer type mismatches.
711 ; Documented in common.opt
713 Werror-implicit-function-declaration
714 C ObjC RejectNegative Warning Alias(Werror=, implicit-function-declaration)
715 This switch is deprecated; use -Werror=implicit-function-declaration instead.
718 C++ ObjC++ Var(warn_exceptions) Init(1) Warning
719 Warn when an exception handler is shadowed by another handler.
721 Wexpansion-to-defined
722 C ObjC C++ ObjC++ CPP(warn_expansion_to_defined) CppReason(CPP_W_EXPANSION_TO_DEFINED) Var(cpp_warn_expansion_to_defined) Init(0) Warning EnabledBy(Wextra || Wpedantic)
723 Warn if \"defined\" is used outside #if.
726 C ObjC C++ ObjC++ Warning
730 C++ ObjC++ Var(warn_extra_semi) Warning
731 Warn about semicolon after in-class function definition.
733 Wflex-array-member-not-at-end
734 C C++ Var(warn_flex_array_member_not_at_end) Warning
735 Warn when a structure containing a C99 flexible array member as the last
736 field is not at the end of another structure.
739 C ObjC C++ ObjC++ Var(warn_float_conversion) Warning LangEnabledBy(C ObjC C++ ObjC++,Wconversion)
740 Warn for implicit type conversions that cause loss of floating point precision.
743 C ObjC C++ ObjC++ Var(warn_float_equal) Warning
744 Warn if testing floating point numbers for equality.
747 C ObjC C++ ObjC++ Warning Alias(Wformat=, 1, 0)
748 Warn about printf/scanf/strftime/strfmon format string anomalies.
751 C ObjC C++ ObjC++ Var(warn_format_contains_nul) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 1, 0)
752 Warn about format strings that contain NUL bytes.
755 C ObjC C++ ObjC++ Var(warn_format_diag) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 1, 0)
756 Warn about GCC format strings with strings unsuitable for diagnostics.
759 C ObjC C++ ObjC++ Var(warn_format_extra_args) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 1, 0)
760 Warn if passing too many arguments to a function for its format string.
763 C ObjC C++ ObjC++ Var(warn_format_nonliteral) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 2, 0)
764 Warn about format strings that are not literals.
767 C ObjC C++ LTO ObjC++ Warning Alias(Wformat-overflow=, 1, 0) IntegerRange(0, 2)
768 Warn about function calls with format strings that write past the end
769 of the destination region. Same as -Wformat-overflow=1.
772 C ObjC C++ LTO ObjC++ Joined RejectNegative UInteger Var(warn_format_overflow) Warning LangEnabledBy(C ObjC C++ LTO ObjC++,Wformat=, warn_format >= 1, 0) IntegerRange(0, 2)
773 Warn about function calls with format strings that write past the end
774 of the destination region.
777 C ObjC C++ ObjC++ Var(warn_format_security) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 2, 0)
778 Warn about possible security problems with format functions.
781 C ObjC C++ ObjC++ Var(warn_format_signedness) Warning
782 Warn about sign differences with format functions.
785 C ObjC C++ LTO ObjC++ Warning Alias(Wformat-truncation=, 1, 0)
786 Warn about calls to snprintf and similar functions that truncate output.
787 Same as -Wformat-truncation=1.
790 C ObjC C++ LTO ObjC++ Joined RejectNegative UInteger Var(warn_format_trunc) Warning LangEnabledBy(C ObjC C++ LTO ObjC++,Wformat=, warn_format >= 1, 0) IntegerRange(0, 2)
791 Warn about calls to snprintf and similar functions that truncate output.
794 C ObjC C++ ObjC++ Var(warn_format_y2k) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=,warn_format >= 2, 0)
795 Warn about strftime formats yielding 2-digit years.
798 C ObjC C++ ObjC++ Var(warn_format_zero_length) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=,warn_format >= 1, 0)
799 Warn about zero-length formats.
802 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_format) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0) IntegerRange(0, 2)
803 Warn about printf/scanf/strftime/strfmon format string anomalies.
806 C ObjC C++ ObjC++ Var(warn_frame_address) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
807 Warn when __builtin_frame_address or __builtin_return_address is used unsafely.
810 C++ ObjC++ Var(warn_global_module) Warning Init(1)
811 Warn about the global module fragment not containing only preprocessing directives.
814 C ObjC C++ ObjC++ Var(warn_if_not_aligned) Init(1) Warning
815 Warn when the field in a struct is not aligned.
818 C C++ Var(warn_ignored_qualifiers) Warning EnabledBy(Wextra)
819 Warn whenever type qualifiers are ignored.
822 C C++ Var(warn_ignored_attributes) Init(1) Warning
823 Warn whenever attributes are ignored.
826 C ObjC Var(warn_implicit) Warning LangEnabledBy(C ObjC,Wall)
827 Warn about implicit declarations.
829 Wimplicit-fallthrough=
830 LangEnabledBy(C ObjC C++ ObjC++,Wextra,3,0)
833 Wimplicit-function-declaration
834 C ObjC Var(warn_implicit_function_declaration) Init(-1) Warning LangEnabledBy(C ObjC,Wimplicit)
835 Warn about implicit function declarations.
838 C ObjC Var(warn_implicit_int) Init(-1) Warning LangEnabledBy(C ObjC,Wimplicit)
839 Warn when a declaration does not specify a type.
842 C ObjC C++ ObjC++ Undocumented Ignore
845 C++ ObjC++ Var(warn_inaccessible_base) Init(1) Warning
846 Warn when a base is inaccessible in derived due to ambiguity.
848 Wincompatible-pointer-types
849 C ObjC Var(warn_incompatible_pointer_types) Init(1) Warning
850 Warn when there is a conversion between pointers that have incompatible types.
853 C ObjC C++ LTO ObjC++ Var(warn_infinite_recursion) Warning LangEnabledBy(C ObjC C++ LTO ObjC++, Wall)
854 Warn for infinitely recursive calls.
857 C ObjC C++ ObjC++ Var(warn_init_self) Warning LangEnabledBy(C++ ObjC++,Wall)
858 Warn about variables which are initialized to themselves.
861 C++ ObjC++ Var(warn_init_list) Warning Init(1)
862 Warn about uses of std::initializer_list that can result in dangling pointers.
865 C++ ObjC++ Var(warn_interference_size) Warning Init(1)
866 Warn about nonsensical values of --param destructive-interference-size or
867 constructive-interference-size.
869 Winherited-variadic-ctor
870 C++ ObjC++ Var(warn_inh_var_ctor) Init(1) Warning
871 Warn about C++11 inheriting constructors when the base has a variadic constructor.
874 C ObjC Var(warn_int_conversion) Init(1) Warning
875 Warn about incompatible integer to pointer and pointer to integer conversions.
878 C ObjC C++ ObjC++ Var(warn_int_in_bool_context) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
879 Warn for suspicious integer expressions in boolean context.
882 C ObjC C++ ObjC++ Var(warn_int_to_pointer_cast) Init(1) Warning
883 Warn when there is a cast to a pointer from an integer of a different size.
886 C++ ObjC++ Var(warn_invalid_constexpr) Init(-1) Warning
887 Warn when a function never produces a constant expression.
890 C++ ObjC++ Var(warn_invalid_offsetof) Init(1) Warning
891 Warn about invalid uses of the \"offsetof\" macro.
894 C ObjC C++ ObjC++ CPP(warn_invalid_pch) CppReason(CPP_W_INVALID_PCH) Var(cpp_warn_invalid_pch) Init(0) Warning
895 Warn about PCH files that are found but not used.
898 C ObjC C++ ObjC++ CPP(cpp_warn_invalid_utf8) CppReason(CPP_W_INVALID_UTF8) Var(warn_invalid_utf8) Init(0) Warning
899 Warn about invalid UTF-8 characters.
902 C ObjC Var(warn_jump_misses_init) Warning LangEnabledby(C ObjC,Wc++-compat)
903 Warn when a jump misses a variable initialization.
906 C++ ObjC++ CPP(warn_literal_suffix) CppReason(CPP_W_LITERAL_SUFFIX) Var(cpp_warn_literal_suffix) Init(1) Warning
907 Warn when a string or character literal is followed by a ud-suffix which does not begin with an underscore.
909 Wlogical-not-parentheses
910 C ObjC C++ ObjC++ Var(warn_logical_not_paren) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
911 Warn when logical not is used on the left hand side operand of a comparison.
914 C ObjC C++ ObjC++ Var(warn_logical_op) Init(0) Warning
915 Warn when a logical operator is suspiciously always evaluating to true or false.
918 C ObjC C++ ObjC++ CPP(cpp_warn_long_long) CppReason(CPP_W_LONG_LONG) Var(warn_long_long) Init(-1) Warning LangEnabledBy(C ObjC,Wc90-c99-compat)
919 Do not warn about using \"long long\" when -pedantic.
922 C ObjC C++ ObjC++ Var(warn_main) Init(-1) Warning LangEnabledBy(C ObjC,Wall, 2, 0)
923 Warn about suspicious declarations of \"main\".
926 LangEnabledBy(C ObjC C++ ObjC++,Wpedantic, 2, 0)
930 C ObjC C++ ObjC++ LTO LangEnabledBy(C ObjC C++ ObjC++ LTO,Wall)
934 C ObjC C++ ObjC++ Var(warn_memset_elt_size) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
935 Warn about suspicious calls to memset where the third argument contains the number of elements not multiplied by the element size.
937 Wmemset-transposed-args
938 C ObjC C++ ObjC++ Var(warn_memset_transposed_args) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
939 Warn about suspicious calls to memset where the third argument is constant literal zero and the second is not.
941 Wmisleading-indentation
942 C C++ Common Var(warn_misleading_indentation) Warning LangEnabledBy(C C++,Wall)
943 Warn when the indentation of the code does not reflect the block structure.
946 C ObjC C++ ObjC++ Var(warn_mismatched_alloc) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
947 Warn for deallocation calls with arguments returned from mismatched allocation
950 Wmismatched-new-delete
951 C++ ObjC++ Var(warn_mismatched_new_delete) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
952 Warn for mismatches between calls to operator new or delete and the corresponding
953 call to the allocation or deallocation function.
956 C++ ObjC++ Var(warn_mismatched_tags) Warning
957 Warn when a class is redeclared or referenced using a mismatched class-key.
960 C ObjC C++ ObjC++ Var(warn_missing_attributes) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
961 Warn about declarations of entities that may be missing attributes
962 that related entities have been declared with.
965 C ObjC C++ ObjC++ Var(warn_missing_braces) Warning LangEnabledBy(C ObjC,Wall)
966 Warn about possibly missing braces around initializers.
968 Wmissing-declarations
969 C ObjC C++ ObjC++ Var(warn_missing_declarations) Warning
970 Warn about global functions without previous declarations.
972 Wmissing-field-initializers
973 C ObjC C++ ObjC++ Var(warn_missing_field_initializers) Warning EnabledBy(Wextra)
974 Warn about missing fields in struct initializers.
976 Wmissing-format-attribute
977 C ObjC C++ ObjC++ Warning Alias(Wsuggest-attribute=format)
980 Wmissing-include-dirs
981 C ObjC C++ ObjC++ CPP(warn_missing_include_dirs) CppReason(CPP_W_MISSING_INCLUDE_DIRS) Var(cpp_warn_missing_include_dirs) Init(0) Warning
982 Warn about user-specified include directories that do not exist.
984 Wmissing-parameter-type
985 C ObjC Var(warn_missing_parameter_type) Warning EnabledBy(Wextra)
986 Warn about function parameters declared without a type specifier in K&R-style functions.
989 C ObjC Var(warn_missing_prototypes) Warning
990 Warn about global functions without prototypes.
993 C++ ObjC++ Var(warn_missing_requires) Init(1) Warning
994 Warn about likely missing requires keyword.
996 Wmissing-template-keyword
997 C++ ObjC++ Var(warn_missing_template_keyword) Init(1) Warning
998 Warn when the template keyword is missing after a member access token in a dependent member access expression if that member is a template.
1000 Wmissing-variable-declarations
1001 C ObjC Var(warn_missing_variable_declarations) Warning
1002 Warn about global variables without previous declarations.
1005 C ObjC C++ ObjC++ WarnRemoved
1008 C ObjC C++ ObjC++ CPP(warn_multichar) CppReason(CPP_W_MULTICHAR) Var(cpp_warn_multichar) Init(0) Warning
1009 Warn about use of multi-character character constants.
1011 Wmultiple-inheritance
1012 C++ ObjC++ Var(warn_multiple_inheritance) Warning
1013 Warn on direct multiple inheritance.
1015 Wmultistatement-macros
1016 C ObjC C++ ObjC++ Var(warn_multistatement_macros) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1017 Warn about unsafe macros expanding to multiple statements used as a body of a clause such as if, else, while, switch, or for.
1020 C++ ObjC++ Var(warn_namespaces) Warning
1021 Warn on namespace definition.
1024 C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(-1) LangEnabledBy(C++ ObjC++,Wall || Wc++11-compat)
1025 Warn about narrowing conversions within { } that are ill-formed in C++11.
1028 C ObjC Var(warn_nested_externs) Warning
1029 Warn about \"extern\" declarations not at file scope.
1032 C++ ObjC++ Var(warn_noexcept) Warning
1033 Warn when a noexcept expression evaluates to false even though the expression can't actually throw.
1036 C++ ObjC++ Warning Var(warn_noexcept_type) LangEnabledBy(C++ ObjC++,Wabi || Wc++17-compat)
1037 Warn if C++17 noexcept function type will change the mangled name of a symbol.
1039 Wnon-template-friend
1040 C++ ObjC++ Var(warn_nontemplate_friend) Init(1) Warning
1041 Warn when non-templatized friend functions are declared within a template.
1044 C++ ObjC++ Var(warn_nonvdtor) Warning LangEnabledBy(C++ ObjC++,Weffc++)
1045 Warn about non-virtual destructors.
1048 C ObjC C++ LTO ObjC++ Var(warn_nonnull) Warning LangEnabledBy(C ObjC C++ LTO ObjC++,Wformat=,warn_format >= 1,0)
1049 Warn about NULL being passed to argument slots marked as requiring non-NULL.
1052 C ObjC C++ LTO ObjC++ LangEnabledBy(C ObjC C++ LTO ObjC++,Wall)
1056 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall)
1060 C ObjC C++ ObjC++ Warning Alias(Wnormalized=,nfc,none)
1064 C ObjC C++ ObjC++ RejectNegative Joined Warning CPP(warn_normalize) CppReason(CPP_W_NORMALIZE) Init(normalized_C) Var(cpp_warn_normalize) Enum(cpp_normalize_level)
1065 -Wnormalized=[none|id|nfc|nfkc] Warn about non-normalized Unicode strings.
1067 ; Required for these enum values.
1072 Name(cpp_normalize_level) Type(int) UnknownError(argument %qs to %<-Wnormalized%> not recognized)
1075 Enum(cpp_normalize_level) String(none) Value(normalized_none)
1078 Enum(cpp_normalize_level) String(nfkc) Value(normalized_KC)
1081 Enum(cpp_normalize_level) String(id) Value(normalized_identifier_C)
1084 Enum(cpp_normalize_level) String(nfc) Value(normalized_C)
1087 ObjC ObjC++ Var(warn_objc_root_class) Warning Init(1)
1088 Warn if a class interface has no superclass. Root classes may use an attribute
1089 to suppress this warning.
1092 C++ ObjC++ Var(warn_old_style_cast) Warning
1093 Warn if a C-style cast is used in a program.
1095 Wold-style-declaration
1096 C ObjC Var(warn_old_style_declaration) Warning EnabledBy(Wextra)
1097 Warn for obsolescent usage in a declaration.
1099 Wold-style-definition
1100 C ObjC Var(warn_old_style_definition) Init(-1) Warning
1101 Warn if an old-style parameter definition is used.
1103 Wopenacc-parallelism
1104 C C++ Var(warn_openacc_parallelism) Warning
1105 Warn about potentially suboptimal choices related to OpenACC parallelism.
1108 C ObjC C++ ObjC++ Warning Var(warn_openmp) Init(1)
1109 Warn about suspicious OpenMP code.
1112 C C++ Var(warn_openmp_simd) Warning LangEnabledBy(C C++,Wall)
1113 Warn if a simd directive is overridden by the vectorizer cost model.
1116 C ObjC C++ ObjC++ Var(warn_overlength_strings) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic)
1117 Warn if a string is longer than the maximum portable length specified by the standard.
1120 C++ ObjC++ Warning Alias(Woverloaded-virtual=,2,0)
1121 Warn about overloaded virtual function names.
1123 Woverloaded-virtual=
1124 C++ ObjC++ Joined UInteger IntegerRange(0,2) Var(warn_overloaded_virtual) Warning LangEnabledBy(C++ ObjC++,Wall,1,0)
1125 Warn about overloaded virtual function names.
1128 C ObjC Var(warn_override_init) Warning EnabledBy(Wextra)
1129 Warn about overriding initializers without side effects.
1131 Woverride-init-side-effects
1132 C ObjC Var(warn_override_init_side_effects) Init(1) Warning
1133 Warn about overriding initializers with side effects.
1136 C++ ObjC++ Var(warn_nrvo)
1137 Warn if the named return value optimization is not performed although it is allowed.
1139 Wpacked-bitfield-compat
1140 C ObjC C++ ObjC++ Var(warn_packed_bitfield_compat) Init(-1) Warning
1141 Warn about packed bit-fields whose offset changed in GCC 4.4.
1144 C ObjC C++ ObjC++ Var(warn_packed_not_aligned) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1145 Warn when fields in a struct with the packed attribute are misaligned.
1148 C ObjC C++ ObjC++ Var(warn_parentheses) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1149 Warn about possibly missing parentheses.
1152 C ObjC C++ ObjC++ CPP(cpp_pedantic) CppReason(CPP_W_PEDANTIC) Warning
1153 ; Documented in common.opt
1156 C++ ObjC++ Var(warn_pessimizing_move) Warning LangEnabledBy(C++ ObjC++, Wall)
1157 Warn about calling std::move on a local object in a return statement preventing copy elision.
1160 C++ Warning Alias(Wplacement-new=, 1, 0)
1161 Warn for placement new expressions with undefined behavior.
1164 C++ Joined RejectNegative UInteger Var(warn_placement_new) Init(-1) Warning IntegerRange(0, 2)
1165 Warn for placement new expressions with undefined behavior.
1168 C++ ObjC++ Var(warn_pmf2ptr) Init(1) Warning
1169 Warn when converting the type of pointers to member functions.
1172 C ObjC C++ ObjC++ Var(warn_pointer_arith) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic)
1173 Warn about function pointer arithmetic.
1176 C ObjC Var(warn_pointer_sign) Warning LangEnabledBy(C ObjC,Wall || Wpedantic)
1177 Warn when a pointer differs in signedness in an assignment.
1180 C ObjC C++ ObjC++ Var(warn_pointer_compare) Init(1) Warning
1181 Warn when a pointer is compared with a zero character constant.
1183 Wpointer-to-int-cast
1184 C ObjC Var(warn_pointer_to_int_cast) Init(1) Warning
1185 Warn when a pointer is cast to an integer of a different size.
1188 C ObjC C++ ObjC++ Var(warn_pragmas) Init(1) Warning
1189 Warn about misuses of pragmas.
1192 C ObjC C++ ObjC++ Var(warn_prio_ctor_dtor) Init(1) Warning
1193 Warn if constructor or destructors with priorities from 0 to 100 are used.
1195 Wproperty-assign-default
1196 ObjC ObjC++ Var(warn_property_assign_default) Init(1) Warning
1197 Warn if a property for an Objective-C object has no assign semantics specified.
1200 ObjC ObjC++ Var(warn_protocol) Init(1) Warning
1201 Warn if inherited methods are unimplemented.
1203 Wrange-loop-construct
1204 C++ ObjC++ Var(warn_range_loop_construct) Warning LangEnabledBy(C++ ObjC++,Wall)
1205 Warn when a range-based for-loop is creating unnecessary copies.
1208 C ObjC C++ ObjC++ Var(warn_redundant_decls) Warning
1209 Warn about multiple declarations of the same object.
1212 C++ ObjC++ Var(warn_redundant_move) Warning LangEnabledBy(C++ ObjC++,Wextra)
1213 Warn about redundant calls to std::move.
1216 C++ ObjC++ Var(warn_redundant_tags) Warning
1217 Warn when a class or enumerated type is referenced using a redundant class-key.
1220 C++ ObjC++ Var(warn_register) Warning
1221 Warn about uses of register storage specifier.
1224 C++ ObjC++ Var(warn_reorder) Warning LangEnabledBy(C++ ObjC++,Wall)
1225 Warn when the compiler reorders code.
1228 C ObjC C++ ObjC++ Var(warn_restrict) Warning LangEnabledBy(C ObjC C++ ObjC++, Wall)
1229 Warn when an argument passed to a restrict-qualified parameter aliases with
1233 C ObjC Var(warn_return_mismatch) Warning Init(1)
1234 Warn whenever void-returning functions return a non-void expressions, or a return expression is missing in a function not returning void.
1237 C ObjC C++ ObjC++ Var(warn_return_type) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall) Init(-1)
1238 Warn whenever a function's return type defaults to \"int\" (C), or about inconsistent return types (C++).
1240 Wscalar-storage-order
1241 C ObjC C++ ObjC++ Var(warn_scalar_storage_order) Init(1) Warning
1242 Warn on suspicious constructs involving reverse scalar storage order.
1245 ObjC ObjC++ Var(warn_selector) Warning
1246 Warn if a selector has multiple methods.
1249 C++ ObjC++ Var(warn_self_move) Warning LangEnabledBy(C++ ObjC++, Wall)
1250 Warn when a value is moved to itself with std::move.
1253 C ObjC C++ ObjC++ Var(warn_sequence_point) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1254 Warn about possible violations of sequence point rules.
1257 ObjC ObjC++ Var(warn_shadow_ivar) EnabledBy(Wshadow) Init(1) Warning
1258 Warn if a local declaration hides an instance variable.
1261 C ObjC C++ ObjC++ Warning Alias(Wshift-overflow=, 1, 0)
1262 Warn if left shift of a signed value overflows.
1265 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_shift_overflow) Init(-1) Warning IntegerRange(0, 2)
1266 Warn if left shift of a signed value overflows.
1268 Wshift-count-negative
1269 C ObjC C++ ObjC++ Var(warn_shift_count_negative) Init(1) Warning
1270 Warn if shift count is negative.
1272 Wshift-count-overflow
1273 C ObjC C++ ObjC++ Var(warn_shift_count_overflow) Init(1) Warning
1274 Warn if shift count >= width of type.
1276 Wshift-negative-value
1277 C ObjC C++ ObjC++ Var(warn_shift_negative_value) Init(-1) Warning
1278 Warn if left shifting a negative value.
1281 C ObjC C++ ObjC++ Var(warn_sign_compare) Warning LangEnabledBy(C++ ObjC++,Wall)
1282 Warn about signed-unsigned comparisons.
1285 C ObjC C++ ObjC++ EnabledBy(Wextra)
1289 C ObjC C++ ObjC++ Var(warn_sign_conversion) Warning LangEnabledBy(C ObjC,Wconversion)
1290 Warn for implicit type conversions between signed and unsigned integers.
1293 C++ ObjC++ Var(warn_sign_promo) Warning
1294 Warn when overload promotes from unsigned to signed.
1297 C++ ObjC++ Var(warn_sized_deallocation) Warning EnabledBy(Wextra)
1298 Warn about missing sized deallocation functions.
1301 C ObjC C++ ObjC++ Var(warn_sizeof_array_div) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1302 Warn about divisions of two sizeof operators when the first one is applied
1303 to an array and the divisor does not equal the size of the array element.
1305 Wsizeof-array-argument
1306 C ObjC C++ ObjC++ Var(warn_sizeof_array_argument) Warning Init(1)
1307 Warn when sizeof is applied on a parameter declared as an array.
1310 C ObjC C++ ObjC++ Var(warn_sizeof_pointer_div) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1311 Warn about suspicious divisions of two sizeof expressions that don't work correctly with pointers.
1313 Wsizeof-pointer-memaccess
1314 C ObjC C++ ObjC++ Var(warn_sizeof_pointer_memaccess) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1315 Warn about suspicious length parameters to certain string functions if the argument uses sizeof.
1318 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall, 3, 0) IntegerRange(0, 3)
1322 C C++ Var(warn_strict_flex_arrays) Warning
1323 Warn about improper usages of flexible array members
1324 according to the level of -fstrict-flex-arrays.
1326 Wstrict-null-sentinel
1327 C++ ObjC++ Warning Var(warn_strict_null_sentinel)
1328 Warn about uncasted NULL used as sentinel.
1331 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0) IntegerRange(0, 5)
1335 C ObjC Var(warn_strict_prototypes) Warning
1336 Warn about unprototyped function declarations.
1338 Wstrict-selector-match
1339 ObjC ObjC++ Var(warn_strict_selector_match) Warning
1340 Warn if type signatures of candidate methods do not match exactly.
1343 C ObjC C++ LTO ObjC++ Warning Var(warn_string_compare) Warning LangEnabledBy(C ObjC C++ ObjC++, Wextra)
1344 Warn about calls to strcmp and strncmp used in equality expressions that
1345 are necessarily true or false due to the length of one and size of the other
1349 C ObjC C++ LTO ObjC++ Warning Alias(Wstringop-overflow=, 2, 0)
1350 Warn about buffer overflow in string manipulation functions like memcpy
1354 C ObjC C++ LTO ObjC++ Joined RejectNegative UInteger Var(warn_stringop_overflow) Init(2) Warning LangEnabledBy(C ObjC C++ LTO ObjC++, Wall, 2, 0) IntegerRange(0, 4)
1355 Under the control of Object Size type, warn about buffer overflow in string
1356 manipulation functions like memcpy and strcpy.
1359 C ObjC C++ LTO ObjC++ Var(warn_stringop_overread) Init(1) Warning LangEnabledBy(C ObjC C++ LTO ObjC++, Wall)
1360 Warn about reading past the end of a source array in string manipulation functions like memchr and memcpy.
1362 Wstringop-truncation
1363 C ObjC C++ LTO ObjC++ Var(warn_stringop_truncation) Warning Init (1) LangEnabledBy(C ObjC C++ LTO ObjC++, Wall)
1364 Warn about truncation in string manipulation functions like strncat and strncpy.
1367 C++ ObjC++ Var(warn_subobject_linkage) Warning Init(1)
1368 Warn if a class type has a base or a field whose type uses the anonymous namespace or depends on a type with no linkage.
1370 Wsuggest-attribute=format
1371 C ObjC C++ ObjC++ Var(warn_suggest_attribute_format) Warning
1372 Warn about functions which might be candidates for format attributes.
1375 C++ ObjC++ Var(warn_override) Warning
1376 Suggest that the override keyword be used when the declaration of a virtual
1377 function overrides another.
1380 C ObjC C++ ObjC++ Var(warn_switch) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1381 Warn about enumerated switches, with no default, missing a case.
1384 C ObjC C++ ObjC++ Var(warn_switch_default) Warning
1385 Warn about enumerated switches missing a \"default:\" statement.
1388 C ObjC C++ ObjC++ Var(warn_switch_enum) Warning
1389 Warn about all enumerated switches missing a specific case.
1392 C ObjC C++ ObjC++ Var(warn_switch_bool) Warning Init(1)
1393 Warn about switches with boolean controlling expression.
1395 Wswitch-outside-range
1396 C ObjC C++ ObjC++ Var(warn_switch_outside_range) Warning Init(1)
1397 Warn about switch values that are outside of the switch's type range.
1400 C C++ Var(warn_sync_nand) Init(1) Warning
1401 Warn when __sync_fetch_and_nand and __sync_nand_and_fetch built-in functions are used.
1404 C++ ObjC++ Var(warn_synth) Warning
1405 Deprecated. This switch has no effect.
1408 C ObjC C++ ObjC++ Warning
1409 ; Documented in common.opt
1412 C++ ObjC++ Var(warn_templates) Warning
1413 Warn on primary template declaration.
1415 Wtautological-compare
1416 C ObjC C++ ObjC++ Var(warn_tautological_compare) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1417 Warn if a comparison always evaluates to true or false.
1420 C++ ObjC++ Var(warn_template_id_cdtor) Warning
1421 Warn about simple-template-id in a constructor or destructor.
1424 C++ ObjC++ Warning Var(warn_terminate) Init(1)
1425 Warn if a throw expression will always result in a call to terminate().
1428 C ObjC CPP(cpp_warn_traditional) CppReason(CPP_W_TRADITIONAL) Var(warn_traditional) Init(0) Warning
1429 Warn about features not present in traditional C.
1431 Wtraditional-conversion
1432 C ObjC Var(warn_traditional_conversion) Warning
1433 Warn of prototypes causing type conversions different from what would happen in the absence of prototype.
1436 C ObjC C++ ObjC++ CPP(warn_trigraphs) CppReason(CPP_W_TRIGRAPHS) Var(cpp_warn_trigraphs) Init(2) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1437 Warn if trigraphs are encountered that might affect the meaning of the program.
1439 Wundeclared-selector
1440 ObjC ObjC++ Var(warn_undeclared_selector) Warning
1441 Warn about @selector()s without previously declared methods.
1444 C ObjC C++ ObjC++ CPP(warn_undef) CppReason(CPP_W_UNDEF) Var(cpp_warn_undef) Init(0) Warning
1445 Warn if an undefined macro is used in an #if directive.
1448 C ObjC C++ ObjC++ CPP(cpp_warn_unicode) CppReason(CPP_W_UNICODE) Var(warn_unicode) Init(1) Warning
1449 Warn about invalid forms of delimited or named escape sequences.
1452 C ObjC C++ ObjC++ LTO LangEnabledBy(C ObjC C++ ObjC++ LTO,Wall)
1456 C ObjC C++ ObjC++ Warning Var(warn_unknown_pragmas) LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0)
1457 Warn about unrecognized pragmas.
1459 Wunsuffixed-float-constants
1460 C ObjC Var(warn_unsuffixed_float_constants) Warning
1461 Warn about unsuffixed float constants.
1464 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall)
1465 ; documented in common.opt
1467 Wunused-const-variable
1468 C ObjC C++ ObjC++ Warning Alias(Wunused-const-variable=, 2, 0)
1469 Warn when a const variable is unused.
1471 Wunused-const-variable=
1472 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_unused_const_variable) Warning LangEnabledBy(C ObjC,Wunused-variable, 1, 0) IntegerRange(0, 2)
1473 Warn when a const variable is unused.
1475 Wunused-local-typedefs
1476 C ObjC C++ ObjC++ Var(warn_unused_local_typedefs) Warning EnabledBy(Wunused)
1477 Warn when typedefs locally defined in a function are not used.
1480 C ObjC C++ ObjC++ CppReason(CPP_W_UNUSED_MACROS) Var(cpp_warn_unused_macros) Warning
1481 Warn about macros defined in the main file that are not used.
1484 C ObjC C++ ObjC++ Var(warn_unused_result) Init(1) Warning
1485 Warn if a caller of a function, marked with attribute warn_unused_result, does not use its return value.
1488 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wunused)
1489 ; documented in common.opt
1491 ; Defining this option here in addition to common.opt is necessary
1492 ; in order for the default -Wall setting of -Wuse-after-free=2 to take
1496 LangEnabledBy(C ObjC C++ LTO ObjC++, Wall,2,0)
1500 C ObjC C++ ObjC++ Var(warn_useless_cast) Warning
1501 Warn about useless casts.
1504 C ObjC C++ ObjC++ CPP(warn_variadic_macros) CppReason(CPP_W_VARIADIC_MACROS) Var(cpp_warn_variadic_macros) Init(0) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic || Wtraditional)
1505 Warn about using variadic macros.
1508 C ObjC C++ ObjC++ Warning Var(warn_varargs) Init(1)
1509 Warn about questionable usage of the macros used to retrieve variable arguments.
1512 C++ ObjC++ Warning Var(warn_vexing_parse) Init(1)
1513 Warn about the most vexing parse syntactic ambiguity.
1515 Wvirtual-move-assign
1516 C++ ObjC++ Var(warn_virtual_move_assign) Warning Init(1)
1517 Warn if a virtual base has a non-trivial move assignment operator.
1520 C ObjC C++ ObjC++ Var(warn_vla) Init(-1) Warning
1521 Warn if a variable length array is used.
1524 C ObjC C++ LTO ObjC++ Var(warn_vla_limit) Warning Joined Host_Wide_Int ByteSize Init(HOST_WIDE_INT_MAX)
1525 -Wvla-larger-than=<number> Warn on unbounded uses of variable-length
1526 arrays, and on bounded uses of variable-length arrays whose bound can be
1527 larger than <number> bytes.
1530 C ObjC C++ LTO ObjC++ Alias(Wvla-larger-than=,18446744073709551615EiB,none) Warning
1531 Disable Wvla-larger-than= warning. Equivalent to Wvla-larger-than=<SIZE_MAX> or larger.
1534 C ObjC C++ ObjC++ Var(warn_vla_parameter) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1535 Warn about mismatched declarations of VLA parameters.
1538 C++ ObjC++ Var(warn_volatile) Warning
1539 Warn about deprecated uses of volatile qualifier.
1541 Wvolatile-register-var
1542 C ObjC C++ ObjC++ Var(warn_volatile_register_var) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1543 Warn when a register variable is declared volatile.
1545 Wvirtual-inheritance
1546 C++ ObjC++ Var(warn_virtual_inheritance) Warning
1547 Warn on direct virtual inheritance.
1550 C ObjC C++ ObjC++ Var(warn_write_strings) Warning
1551 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.
1554 C ObjC C++ ObjC++ Var(warn_xor_used_as_pow) Warning Init(1)
1555 Warn about xor operators where it appears the user meant exponentiation.
1557 Wzero-as-null-pointer-constant
1558 C++ ObjC++ Var(warn_zero_as_null_pointer_constant) Warning
1559 Warn when a literal '0' is used as null pointer.
1562 C ObjC C++ ObjC++ Var(warn_zero_length_bounds) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1563 Warn about accesses to interior zero-length array members.
1567 A synonym for -std=c89 (for C) or -std=c++98 (for C++).
1570 C ObjC C++ ObjC++ Joined
1571 ; Documented in common.opt. FIXME - what about -dI, -dD, -dN and -dD?
1573 fabi-compat-version=
1574 C++ ObjC++ Joined RejectNegative UInteger Var(flag_abi_compat_version) Init(-1)
1575 The version of the C++ ABI used for -Wabi warnings and link compatibility aliases.
1578 C++ ObjC++ Var(flag_access_control) Init(1)
1579 Enforce class member access control semantics.
1582 C ObjC C++ ObjC++ RejectNegative Joined Var(ada_specs_parent)
1583 -fada-spec-parent=unit Dump Ada specs as child units of given parent.
1586 C++ ObjC++ Alias(faligned-new=,1,0)
1587 Support C++17 allocation of over-aligned types.
1590 C++ ObjC++ Joined RejectNegative Var(aligned_new_threshold) UInteger Init(-1)
1591 -faligned-new=<N> Use C++17 over-aligned type allocation for alignments greater than N.
1594 C++ ObjC++ WarnRemoved
1596 fallow-parameterless-variadic-functions
1598 Does nothing. Preserved for backward compatibility.
1600 falt-external-templates
1601 C++ ObjC++ WarnRemoved
1602 No longer supported.
1605 C ObjC C++ ObjC++ Var(flag_no_asm, 0)
1606 Recognize the \"asm\" keyword.
1608 ; Define extra predefined macros for use in libgcc.
1610 C ObjC C++ ObjC++ Undocumented Var(flag_building_libgcc)
1613 C ObjC C++ ObjC++ Var(flag_no_builtin, 0)
1614 Recognize built-in functions.
1617 C ObjC C++ ObjC++ Joined
1619 fcanonical-system-headers
1621 Where shorter, use canonicalized paths to systems headers.
1624 C++ ObjC++ Var(flag_char8_t) Init(-1)
1625 Enable the char8_t fundamental type and use it as the type for UTF-8 string
1626 and character literals.
1628 fcheck-pointer-bounds
1629 C ObjC C++ ObjC++ LTO WarnRemoved
1630 Removed in GCC 9. This switch has no effect.
1632 fchkp-check-incomplete-type
1633 C ObjC C++ ObjC++ LTO WarnRemoved
1634 Removed in GCC 9. This switch has no effect.
1636 fchkp-zero-input-bounds-for-main
1637 C ObjC C++ ObjC++ LTO WarnRemoved
1638 Removed in GCC 9. This switch has no effect.
1640 fchkp-first-field-has-own-bounds
1641 C ObjC C++ ObjC++ LTO WarnRemoved RejectNegative
1642 Removed in GCC 9. This switch has no effect.
1645 C ObjC C++ ObjC++ LTO WarnRemoved
1646 Removed in GCC 9. This switch has no effect.
1648 fchkp-narrow-to-innermost-array
1649 C ObjC C++ ObjC++ LTO WarnRemoved RejectNegative
1650 Removed in GCC 9. This switch has no effect.
1652 fchkp-flexible-struct-trailing-arrays
1653 C ObjC C++ ObjC++ LTO WarnRemoved
1654 Removed in GCC 9. This switch has no effect.
1657 C ObjC C++ ObjC++ LTO WarnRemoved
1659 fchkp-use-fast-string-functions
1660 C ObjC C++ ObjC++ LTO WarnRemoved
1661 Removed in GCC 9. This switch has no effect.
1663 fchkp-use-nochk-string-functions
1664 C ObjC C++ ObjC++ LTO WarnRemoved
1665 Removed in GCC 9. This switch has no effect.
1667 fchkp-use-static-bounds
1668 C ObjC C++ ObjC++ LTO WarnRemoved
1669 Removed in GCC 9. This switch has no effect.
1671 fchkp-use-static-const-bounds
1672 C ObjC C++ ObjC++ LTO WarnRemoved
1673 Removed in GCC 9. This switch has no effect.
1675 fchkp-treat-zero-dynamic-size-as-infinite
1676 C ObjC C++ ObjC++ LTO WarnRemoved
1677 Removed in GCC 9. This switch has no effect.
1680 C ObjC C++ ObjC++ LTO WarnRemoved
1681 Removed in GCC 9. This switch has no effect.
1684 C ObjC C++ ObjC++ LTO WarnRemoved
1685 Removed in GCC 9. This switch has no effect.
1688 C ObjC C++ ObjC++ LTO WarnRemoved
1689 Removed in GCC 9. This switch has no effect.
1691 fchkp-instrument-calls
1692 C ObjC C++ ObjC++ LTO WarnRemoved
1693 Removed in GCC 9. This switch has no effect.
1695 fchkp-instrument-marked-only
1696 C ObjC C++ ObjC++ LTO WarnRemoved
1697 Removed in GCC 9. This switch has no effect.
1700 C ObjC C++ ObjC++ LTO WarnRemoved
1701 Removed in GCC 9. This switch has no effect.
1705 Removed in GCC 9. This switch has no effect.
1707 static-libmpxwrappers
1709 Removed in GCC 9. This switch has no effect.
1712 C ObjC C++ ObjC++ LTO Undocumented Ignore
1713 Removed in GCC 8. This switch has no effect.
1716 C++ ObjC++ Var(flag_concepts)
1717 Enable support for C++ concepts.
1720 C++ ObjC++ Var(flag_concepts_ts) Init(0)
1721 Enable certain features present in the Concepts TS.
1723 fconcepts-diagnostics-depth=
1724 C++ ObjC++ Joined RejectNegative UInteger Var(concepts_diagnostics_max_depth) Init(1)
1725 Specify maximum error replay depth during recursive diagnosis of a constraint satisfaction failure.
1729 Allow the arguments of the '?' operator to have different types.
1733 Does nothing. Preserved for backward compatibility.
1735 fconstant-string-class=
1736 ObjC ObjC++ Joined MissingArgError(no class name specified with %qs)
1737 -fconst-string-class=<name> Use class <name> for constant strings.
1740 C++ ObjC++ Joined RejectNegative UInteger Var(max_constexpr_depth) Init(512)
1741 -fconstexpr-depth=<number> Specify maximum constexpr recursion depth.
1743 fconstexpr-cache-depth=
1744 C++ ObjC++ Joined RejectNegative UInteger Var(constexpr_cache_depth) Init(8)
1745 -fconstexpr-cache-depth=<number> Specify maximum constexpr recursion cache depth.
1747 fconstexpr-fp-except
1748 C++ ObjC++ Var(flag_constexpr_fp_except) Init(0)
1749 Allow IEC559 floating point exceptions in constant expressions.
1751 fconstexpr-loop-limit=
1752 C++ ObjC++ Joined RejectNegative UInteger Var(constexpr_loop_limit) Init(262144)
1753 -fconstexpr-loop-limit=<number> Specify maximum constexpr loop iteration count.
1755 fconstexpr-ops-limit=
1756 C++ ObjC++ Joined RejectNegative Host_Wide_Int Var(constexpr_ops_limit) Init(33554432)
1757 -fconstexpr-ops-limit=<number> Specify maximum number of constexpr operations during a single constexpr evaluation.
1760 C++ ObjC++ Var(flag_contracts) Init(0)
1761 Enable certain features present in drafts of C++ Contracts.
1764 Name(on_off) Type(int) UnknownError(argument %qs must be either %<on%> or %<off%>)
1767 Enum(on_off) String(off) Value(0)
1770 Enum(on_off) String(on) Value(1)
1772 fcontract-assumption-mode=
1773 C++ Joined RejectNegative
1774 -fcontract-assumption-mode=[on|off] Enable or disable treating axiom level contracts as assumptions (default on).
1776 fcontract-build-level=
1777 C++ Joined RejectNegative
1778 -fcontract-build-level=[off|default|audit] Specify max contract level to generate runtime checks for.
1780 fcontract-strict-declarations=
1781 C++ Var(flag_contract_strict_declarations) Enum(on_off) Joined Init(0) RejectNegative
1782 -fcontract-strict-declarations=[on|off] Enable or disable warnings on generalized redeclaration of functions with contracts (default off).
1785 C++ Var(flag_contract_mode) Enum(on_off) Joined Init(1) RejectNegative
1786 -fcontract-mode=[on|off] Enable or disable all contract facilities (default on).
1788 fcontract-continuation-mode=
1789 C++ Joined RejectNegative
1790 -fcontract-continuation-mode=[on|off] Enable or disable contract continuation mode (default off).
1793 C++ Joined RejectNegative
1794 -fcontract-role=<name>:<semantics> Specify the semantics for all levels in a role (default, review), or a custom contract role with given semantics (ex: opt:assume,assume,assume).
1797 C++ Joined RejectNegative
1798 -fcontract-semantic=<level>:<semantic> Specify the concrete semantics for level.
1801 C++ LTO Var(flag_coroutines)
1802 Enable C++ coroutines (experimental).
1806 Emit debug annotations during preprocessing.
1810 Does nothing. Preserved for backward compatibility.
1813 C++ ObjC++ Var(flag_declone_ctor_dtor) Init(-1)
1814 Factor complex constructors and destructors to favor space over speed.
1818 Does nothing. Preserved for backward compatibility.
1820 fdiagnostics-show-template-tree
1821 C++ ObjC++ Var(flag_diagnostics_show_template_tree) Init(0)
1822 Print hierarchical comparisons when template types are mismatched.
1824 fdiagnostics-all-candidates
1825 C++ ObjC++ Var(flag_diagnostics_all_candidates)
1826 Note all candidates during overload resolution failure.
1830 Preprocess directives only.
1832 fdollars-in-identifiers
1834 Permit '$' as an identifier character.
1837 C ObjC C++ ObjC++ Joined RejectNegative
1838 -fmacro-prefix-map=<old>=<new> Map one directory name to another in __FILE__, __BASE_FILE__, and __builtin_FILE().
1841 C ObjC C++ ObjC++ RejectNegative Var(flag_dump_ada_spec)
1842 Write all declarations as Ada code transitively.
1845 C ObjC C++ ObjC++ RejectNegative Var(flag_dump_ada_spec_slim)
1846 Write all declarations as Ada code for the given file only.
1849 C++ ObjC++ Var(flag_elide_constructors) Init(1)
1852 C++ ObjC++ Var(flag_elide_type) Init(1)
1853 Do not elide common elements in template comparisons.
1856 C++ ObjC++ Var(flag_enforce_eh_specs) Init(1)
1857 Generate code to check exception specifications.
1860 C++ ObjC++ WarnRemoved
1863 C ObjC C++ ObjC++ Joined RejectNegative
1864 -fexec-charset=<cset> Convert all strings and character constants to character set <cset>.
1866 fextended-identifiers
1868 Permit universal character names (\\u and \\U) in identifiers.
1871 C ObjC C++ ObjC++ Joined RejectNegative
1872 -finput-charset=<cset> Specify the default character set for source files.
1875 C++ ObjC++ Var(flag_extern_tls_init) Init(-1)
1876 Support dynamic initialization of thread-local variables in a different translation unit.
1879 C++ ObjC++ WarnRemoved
1881 ffold-simple-inlines
1882 C++ ObjC++ Optimization Var(flag_fold_simple_inlines)
1883 Fold calls to simple inline functions.
1886 C++ ObjC++ WarnRemoved
1890 Do not assume that standard C libraries and \"main\" exist.
1893 C++ ObjC++ Var(flag_no_gnu_keywords, 0)
1894 Recognize GNU-defined keywords.
1897 ObjC ObjC++ LTO RejectNegative Var(flag_next_runtime,0) Init(NEXT_OBJC_RUNTIME)
1898 Generate code for GNU runtime environment.
1901 C ObjC Var(flag_gnu89_inline) Init(-1)
1902 Use traditional GNU semantics for inline functions.
1905 C++ ObjC++ WarnRemoved
1908 C++ ObjC++ Optimization Alias(fexceptions) Warn({%<-fhandle-exceptions%> has been renamed %<-fexceptions%> (and is now on by default)})
1911 C++ ObjC++ WarnRemoved
1915 Assume normal C execution environment.
1918 C++ ObjC++ WarnRemoved
1919 No longer supported.
1921 fimmediate-escalation
1922 C++ ObjC++ Var(flag_immediate_escalation) Init(1)
1923 Implement P2564 for consteval propagation.
1926 C++ ObjC++ Var(flag_implement_inlines) Init(1)
1927 Export functions even if they can be inlined.
1930 C++ ObjC++ Var(flag_implicit_constexpr)
1931 Make inline functions constexpr by default.
1933 fimplicit-inline-templates
1934 C++ ObjC++ Var(flag_implicit_inline_templates) Init(1)
1935 Emit implicit instantiations of inline templates.
1938 C++ ObjC++ Var(flag_implicit_templates) Init(1)
1939 Emit implicit instantiations of templates.
1941 fnew-inheriting-ctors
1942 C++ ObjC++ Var(flag_new_inheriting_ctors) Init(1)
1943 Implement C++17 inheriting constructor semantics.
1946 C++ ObjC++ WarnRemoved
1948 fkeep-inline-dllexport
1949 C C++ ObjC ObjC++ Var(flag_keep_inline_dllexport) Init(1) Condition(TARGET_DLLIMPORT_DECL_ATTRIBUTES)
1950 Don't emit dllexported inline functions unless needed.
1953 C++ ObjC++ WarnRemoved
1955 flax-vector-conversions
1956 C ObjC C++ ObjC++ Var(flag_lax_vector_conversions)
1957 Allow implicit conversions between vectors with differing numbers of subparts and/or differing element types.
1960 C++ ObjC++ Var(flag_modules) Integer Init(0)
1961 Enable C++ modules-ts (experimental).
1964 C++ ObjC++ Undocumented RejectNegative Var(flag_modules,0) Integer
1968 C++ ObjC RejectNegative Var(flag_header_unit,0) Integer
1969 Enable C++ header module (experimental).
1972 C++ ObjC++ Joined RejectNegative Undocumented
1974 fmodule-implicit-inline
1975 C++ ObjC++ Var(flag_module_implicit_inline,0) Integer
1976 Member functions defined within their class are inline in module purview.
1979 C++ ObjC RejectNegative Var(flag_module_only) Integer
1980 Only emit Compiled Module Interface.
1983 C++ ObjC++ Joined RejectNegative MissingArgError(missing mapper)
1984 Mapper for module to CMI files.
1987 C++ ObjC++ Var(flag_module_lazy) Init(1)
1988 Enable lazy module importing.
1990 fmodule-version-ignore
1991 C++ ObjC Var(flag_module_version_ignore) Integer
1992 ; undocumented, Very dangerous, but occasionally useful
1994 Winvalid-imported-macros
1995 C++ ObjC++ Var(warn_imported_macros) Warning
1996 Warn about macros that have conflicting header units definitions.
1998 Wcompare-distinct-pointer-types
1999 C ObjC Var(warn_compare_distinct_pointer_types) Warning Init(1)
2000 Warn if pointers of distinct types are compared without a cast.
2002 flang-info-include-translate
2003 C++ Var(note_include_translate_yes)
2004 Note #include directives translated to import declarations.
2006 flang-info-include-translate-not
2007 C++ Var(note_include_translate_no)
2008 Note #include directives not translated to import declarations, and not known to be textual.
2010 flang-info-include-translate=
2011 C++ Joined RejectNegative MissingArgError(missing header name)
2012 Note a #include translation of a specific header.
2014 flang-info-module-cmi
2015 C++ Var(note_module_cmi_yes)
2016 Note Compiled Module Interface pathnames.
2018 flang-info-module-cmi=
2019 C++ Joined RejectNegative MissingArgError(missing module name)
2020 Note Compiled Module Interface pathname of a specific module or header-unit.
2023 C ObjC C++ ObjC++ Joined RejectNegative UInteger
2024 fmax-include-depth=<number> Set the maximum depth of the nested #include.
2027 C ObjC C++ ObjC++ Var(flag_ms_extensions)
2028 Don't warn about uses of Microsoft extensions.
2031 C ObjC C++ ObjC++ WarnRemoved
2034 C ObjC C++ ObjC++ WarnRemoved
2037 C ObjC C++ ObjC++ WarnRemoved
2039 fname-mangling-version-
2040 C++ ObjC++ Joined WarnRemoved
2043 C++ ObjC++ WarnRemoved
2046 C++ ObjC++ Var(flag_new_ttp)
2047 Implement resolution of DR 150 for matching of template template arguments.
2050 ObjC ObjC++ LTO RejectNegative Var(flag_next_runtime)
2051 Generate code for NeXT (Apple macOS) runtime environment.
2054 ObjC ObjC++ Var(flag_nil_receivers) Init(1)
2055 Assume that receivers of Objective-C messages may be nil.
2058 ObjC ObjC++ Var(flag_local_ivars) Init(1)
2059 Allow access to instance variables as if they were local declarations within instance method implementations.
2062 ObjC ObjC++ Joined RejectNegative Enum(ivar_visibility) Var(default_ivar_visibility) Init(IVAR_VISIBILITY_PROTECTED)
2063 -fvisibility=[private|protected|public|package] Set the default symbol visibility.
2066 Name(ivar_visibility) Type(enum ivar_visibility) UnknownError(unrecognized ivar visibility value %qs)
2069 Enum(ivar_visibility) String(private) Value(IVAR_VISIBILITY_PRIVATE)
2072 Enum(ivar_visibility) String(protected) Value(IVAR_VISIBILITY_PROTECTED)
2075 Enum(ivar_visibility) String(public) Value(IVAR_VISIBILITY_PUBLIC)
2078 Enum(ivar_visibility) String(package) Value(IVAR_VISIBILITY_PACKAGE)
2081 C++ ObjC++ Var(flag_no_nonansi_builtin, 0)
2084 C++ ObjC++ WarnRemoved
2087 C++ ObjC++ Optimization Var(flag_nothrow_opt)
2088 Treat a throw() exception specification as noexcept to improve code size.
2091 ObjC ObjC++ LTO Joined RejectNegative UInteger Var(flag_objc_abi)
2092 Specify which ABI to use for Objective-C family code and meta-data generation.
2094 ; Generate special '- .cxx_construct' and '- .cxx_destruct' methods
2095 ; to initialize any non-POD ivars in Objective-C++ classes.
2096 fobjc-call-cxx-cdtors
2097 ObjC++ Var(flag_objc_call_cxx_cdtors)
2098 Generate special Objective-C methods to initialize/destroy non-POD C++ ivars, if needed.
2100 fobjc-direct-dispatch
2101 ObjC ObjC++ Var(flag_objc_direct_dispatch)
2102 Allow fast jumps to the message dispatcher.
2104 ; Nonzero means that we will allow new ObjC exception syntax (@throw,
2105 ; @try, etc.) in source code.
2107 ObjC ObjC++ Var(flag_objc_exceptions)
2108 Enable Objective-C exception and synchronization syntax.
2111 ObjC ObjC++ LTO Var(flag_objc_gc)
2112 Enable garbage collection (GC) in Objective-C/Objective-C++ programs.
2115 ObjC ObjC++ Var(flag_objc_nilcheck,1)
2116 Enable inline checks for nil receivers with the NeXT runtime and ABI version 2.
2118 ; Nonzero means that we generate NeXT setjmp based exceptions.
2119 fobjc-sjlj-exceptions
2120 ObjC ObjC++ Var(flag_objc_sjlj_exceptions) Init(-1)
2121 Enable Objective-C setjmp exception handling runtime.
2124 ObjC ObjC++ Var(flag_objc1_only)
2125 Conform to the Objective-C 1.0 language as implemented in GCC 4.0.
2128 C ObjC C++ ObjC++ LTO Var(flag_openacc)
2132 C ObjC C++ ObjC++ LTO Joined Var(flag_openacc_dims)
2133 Specify default OpenACC compute dimensions.
2136 C ObjC C++ ObjC++ LTO Var(flag_openmp)
2137 Enable OpenMP (implies -frecursive in Fortran).
2140 C ObjC C++ ObjC++ Var(flag_openmp_simd)
2141 Enable OpenMP's SIMD directives.
2145 Recognize C++ keywords like \"compl\" and \"xor\".
2149 Does nothing. Preserved for backward compatibility.
2156 Look for and use PCH files even when preprocessing.
2159 C ObjC C++ ObjC++ Var(flag_permissive)
2160 Downgrade conformance errors to warnings.
2163 C ObjC Var(flag_plan9_extensions)
2164 Enable Plan 9 language extensions.
2168 Treat the input file as already preprocessed.
2170 ftrack-macro-expansion
2171 C ObjC C++ ObjC++ JoinedOrMissing RejectNegative UInteger
2172 ; converted into ftrack-macro-expansion=
2174 ftrack-macro-expansion=
2175 C ObjC C++ ObjC++ JoinedOrMissing RejectNegative UInteger
2176 -ftrack-macro-expansion=<0|1|2> Track locations of tokens coming from macro expansion and display them in error messages.
2179 C++ ObjC++ Var(flag_pretty_templates) Init(1)
2180 Do not pretty-print template specializations as the template signature followed by the arguments.
2182 fprintf-return-value
2183 C ObjC C++ ObjC++ LTO Optimization Var(flag_printf_return_value) Init(1)
2184 Treat known sprintf return values as constants.
2186 freplace-objc-classes
2187 ObjC ObjC++ LTO Var(flag_replace_objc_classes)
2188 Used in Fix-and-Continue mode to indicate that object files may be swapped in at runtime.
2191 C++ ObjC++ WarnRemoved
2192 Removed in GCC 10. This switch has no effect.
2195 C++ ObjC++ Optimization Var(flag_rtti) Init(1)
2196 Generate run time type descriptor information.
2199 C ObjC C++ ObjC++ LTO Optimization Var(flag_short_enums)
2200 Use the narrowest integer type possible for enumeration types.
2203 C ObjC C++ ObjC++ LTO Optimization Var(flag_short_wchar)
2204 Force the underlying type for \"wchar_t\" to be \"unsigned short\".
2207 C ObjC C++ ObjC++ Var(flag_signed_bitfields) Init(1)
2208 When \"signed\" or \"unsigned\" is not given make the bitfield signed.
2211 C ObjC C++ ObjC++ LTO Var(flag_signed_char)
2212 Make \"char\" signed by default.
2215 C++ ObjC++ Var(flag_sized_deallocation) Init(-1)
2216 Enable C++14 sized deallocation support.
2219 C C++ Common Alias(fstrict-flex-arrays=,3,0)
2221 fstrict-flex-arrays=
2222 C C++ Common Joined RejectNegative UInteger Var(flag_strict_flex_arrays) Init(0) IntegerRange(0,3)
2223 -fstrict-flex-arrays=<level> Control when to treat the trailing array of a structure as a flexible array member for the purposes of accessing the elements of such an array. The default is treating all trailing arrays of structures as flexible array members.
2226 C++ ObjC++ WarnRemoved
2229 C ObjC Joined RejectNegative Enum(sso_struct) Var(default_sso) Init(SSO_NATIVE)
2230 -fsso-struct=[big-endian|little-endian|native] Set the default scalar storage order.
2233 Name(sso_struct) Type(enum scalar_storage_order_kind) UnknownError(unrecognized scalar storage order value %qs)
2236 Enum(sso_struct) String(big-endian) Value(SSO_BIG_ENDIAN)
2239 Enum(sso_struct) String(little-endian) Value(SSO_LITTLE_ENDIAN)
2242 Enum(sso_struct) String(native) Value(SSO_NATIVE)
2245 C++ ObjC++ Var(flag_detailed_statistics)
2246 Display statistics accumulated during compilation.
2249 C++ ObjC++ Optimization Var(flag_strict_enums)
2250 Assume that values of enumeration type are always within the minimum range of that type.
2253 C++ ObjC++ WarnRemoved
2256 C++ ObjC++ Common Alias(fstrong-eval-order=, all, none)
2257 Follow the C++17 evaluation order requirements for assignment expressions,
2258 shift, member function calls, etc.
2261 C++ ObjC++ Common Var(flag_strong_eval_order) Joined Enum(strong_eval_order) RejectNegative Init(-1)
2262 Follow the C++17 evaluation order requirements for assignment expressions,
2263 shift, member function calls, etc.
2266 Name(strong_eval_order) Type(int)
2269 Enum(strong_eval_order) String(none) Value(0)
2272 Enum(strong_eval_order) String(some) Value(1)
2275 Enum(strong_eval_order) String(all) Value(2)
2277 ftemplate-backtrace-limit=
2278 C++ ObjC++ Joined RejectNegative UInteger Var(template_backtrace_limit) Init(10)
2279 Set the maximum number of template instantiation notes for a single warning or error.
2282 C++ ObjC++ Joined RejectNegative Undocumented Alias(ftemplate-depth=)
2285 C++ ObjC++ Joined RejectNegative UInteger
2286 -ftemplate-depth=<number> Specify maximum template instantiation depth.
2289 C++ ObjC++ WarnRemoved
2292 C++ ObjC++ Optimization Var(flag_threadsafe_statics) Init(1)
2293 -fno-threadsafe-statics Do not generate thread-safe code for initializing local statics.
2296 C ObjC C++ ObjC++ Var(flag_signed_bitfields, 0)
2297 When \"signed\" or \"unsigned\" is not given make the bitfield unsigned.
2300 C ObjC C++ ObjC++ LTO Var(flag_signed_char, 0)
2301 Make \"char\" unsigned by default.
2304 C++ ObjC++ Var(flag_use_cxa_atexit) Init(DEFAULT_USE_CXA_ATEXIT)
2305 Use __cxa_atexit to register destructors.
2307 fuse-cxa-get-exception-ptr
2308 C++ ObjC++ Var(flag_use_cxa_get_exception_ptr) Init(2)
2309 Use __cxa_get_exception_ptr in exception handling.
2311 fvisibility-inlines-hidden
2313 Marks all inlined functions and methods as having hidden visibility.
2315 fvisibility-ms-compat
2316 C++ ObjC++ Var(flag_visibility_ms_compat)
2317 Changes visibility to match Microsoft Visual Studio by default.
2320 C++ ObjC++ WarnRemoved
2321 No longer supported.
2324 C++ ObjC++ WarnRemoved
2325 No longer supported.
2328 C++ ObjC++ Var(flag_weak) Init(1)
2329 Emit common-like symbols as weak symbols.
2332 C ObjC C++ ObjC++ Joined RejectNegative
2333 -fwide-exec-charset=<cset> Convert all wide strings and character constants to character set <cset>.
2336 C ObjC C++ ObjC++ Var(flag_working_directory) Init(-1)
2337 Generate a #line directive pointing at the current working directory.
2340 C++ ObjC++ WarnRemoved
2341 No longer supported.
2344 ObjC ObjC++ Var(flag_zero_link)
2345 Generate lazy class lookup (via objc_getClass()) for use in Zero-Link mode.
2348 ObjC ObjC++ Driver Var(flag_gen_declaration) RejectNegative
2349 Dump declarations to a .decl file.
2351 femit-struct-debug-baseonly
2353 -femit-struct-debug-baseonly Aggressive reduced debug info for structs.
2355 femit-struct-debug-reduced
2357 -femit-struct-debug-reduced Conservative reduced debug info for structs.
2359 femit-struct-debug-detailed=
2360 C ObjC C++ ObjC++ Joined
2361 -femit-struct-debug-detailed=<spec-list> Detailed reduced debug info for structs.
2363 fext-numeric-literals
2364 C++ ObjC++ Var(flag_ext_numeric_literals) Init(1)
2365 Interpret imaginary, fixed-point, or other gnu number suffix as the corresponding
2366 number literal rather than a user-defined number literal.
2369 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2370 -idirafter <dir> Add <dir> to the end of the system include path.
2373 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing filename after %qs)
2374 -imacros <file> Accept definition of macros in <file>.
2377 C ObjC C++ ObjC++ Joined Separate
2378 -imultilib <dir> Set <dir> to be the multilib include subdirectory.
2381 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing filename after %qs)
2382 -include <file> Include the contents of <file> before other files.
2385 C ObjC C++ ObjC++ Joined Separate
2386 -iprefix <path> Specify <path> as a prefix for next two options.
2389 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2390 -isysroot <dir> Set <dir> to be the system root directory.
2393 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2394 -isystem <dir> Add <dir> to the start of the system include path.
2397 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2398 -iquote <dir> Add <dir> to the end of the quote include path.
2401 C ObjC C++ ObjC++ Joined Separate
2402 -iwithprefix <dir> Add <dir> to the end of the system include path.
2405 C ObjC C++ ObjC++ Joined Separate
2406 -iwithprefixbefore <dir> Add <dir> to the end of the main include path.
2409 C Undocumented RejectDriver
2416 Do not search standard system include directories (those specified with -isystem will still be used).
2420 Do not search standard system include directories for C++.
2423 C ObjC C++ ObjC++ Joined Separate
2424 ; Documented in common.opt
2427 C ObjC C++ ObjC++ Alias(Wpedantic)
2428 ; Documented in common.opt
2430 print-objc-runtime-info
2432 Generate C header of platform-specific features.
2436 Remap file names when including files.
2440 Conform to the ISO 1998 C++ standard revised by the 2003 technical corrigendum.
2443 C++ ObjC++ Alias(std=c++98)
2444 Conform to the ISO 1998 C++ standard revised by the 2003 technical corrigendum.
2448 Conform to the ISO 2011 C++ standard.
2451 C++ ObjC++ Alias(std=c++11) Undocumented
2452 Deprecated in favor of -std=c++11.
2455 C++ ObjC++ Alias(std=c++14) Undocumented
2456 Deprecated in favor of -std=c++14.
2460 Conform to the ISO 2014 C++ standard.
2463 C++ ObjC++ Alias(std=c++17) Undocumented
2464 Deprecated in favor of -std=c++17.
2468 Conform to the ISO 2017 C++ standard.
2471 C++ ObjC++ Alias(std=c++20) Undocumented
2472 Conform to the ISO 2020 C++ standard (experimental and incomplete support).
2476 Conform to the ISO 2020 C++ standard (experimental and incomplete support).
2479 C++ ObjC++ Alias(std=c++23) Undocumented
2480 Conform to the ISO 2023 C++ draft standard (experimental and incomplete support).
2484 Conform to the ISO 2023 C++ draft standard (experimental and incomplete support).
2487 C++ ObjC++ Alias(std=c++26)
2488 Conform to the ISO 2026 C++ draft standard (experimental and incomplete support).
2491 C++ ObjC++ Undocumented
2492 Conform to the ISO 2026 C++ draft standard (experimental and incomplete support).
2496 Conform to the ISO 2011 C standard.
2499 C ObjC Alias(std=c11)
2500 Deprecated in favor of -std=c11.
2504 Conform to the ISO 2017 C standard (published in 2018).
2507 C ObjC Alias(std=c17)
2508 Conform to the ISO 2017 C standard (published in 2018).
2512 Conform to the ISO 2023 C standard draft (expected to be published in 2024) (experimental and incomplete support).
2515 C ObjC Alias(std=c23)
2516 Deprecated in favor of -std=c23.
2519 C ObjC Alias(std=c90)
2520 Conform to the ISO 1990 C standard.
2524 Conform to the ISO 1990 C standard.
2528 Conform to the ISO 1999 C standard.
2531 C ObjC Alias(std=c99)
2532 Deprecated in favor of -std=c99.
2536 Conform to the ISO 1998 C++ standard revised by the 2003 technical
2537 corrigendum with GNU extensions.
2540 C++ ObjC++ Alias(std=gnu++98)
2541 Conform to the ISO 1998 C++ standard revised by the 2003 technical
2542 corrigendum with GNU extensions.
2546 Conform to the ISO 2011 C++ standard with GNU extensions.
2549 C++ ObjC++ Alias(std=gnu++11) Undocumented
2550 Deprecated in favor of -std=gnu++11.
2553 C++ ObjC++ Alias(std=gnu++14) Undocumented
2554 Deprecated in favor of -std=gnu++14.
2558 Conform to the ISO 2014 C++ standard with GNU extensions.
2561 C++ ObjC++ Alias(std=gnu++17) Undocumented
2562 Deprecated in favor of -std=gnu++17.
2566 Conform to the ISO 2017 C++ standard with GNU extensions.
2569 C++ ObjC++ Alias(std=gnu++20) Undocumented
2570 Conform to the ISO 2020 C++ standard with GNU extensions (experimental and incomplete support).
2574 Conform to the ISO 2020 C++ standard with GNU extensions (experimental and incomplete support).
2577 C++ ObjC++ Alias(std=gnu++23) Undocumented
2578 Conform to the ISO 2023 C++ draft standard with GNU extensions (experimental and incomplete support).
2582 Conform to the ISO 2023 C++ draft standard with GNU extensions (experimental and incomplete support).
2585 C++ ObjC++ Alias(std=gnu++26)
2586 Conform to the ISO 2026 C++ draft standard with GNU extensions (experimental and incomplete support).
2589 C++ ObjC++ Undocumented
2590 Conform to the ISO 2026 C++ draft standard with GNU extensions (experimental and incomplete support).
2594 Conform to the ISO 2011 C standard with GNU extensions.
2597 C ObjC Alias(std=gnu11)
2598 Deprecated in favor of -std=gnu11.
2602 Conform to the ISO 2017 C standard (published in 2018) with GNU extensions.
2605 C ObjC Alias(std=gnu17)
2606 Conform to the ISO 2017 C standard (published in 2018) with GNU extensions.
2610 Conform to the ISO 2023 C standard draft (expected to be published in 2024) with GNU extensions (experimental and incomplete support).
2613 C ObjC Alias(std=gnu23)
2614 Deprecated in favor of -std=gnu23.
2617 C ObjC Alias(std=gnu90)
2618 Conform to the ISO 1990 C standard with GNU extensions.
2622 Conform to the ISO 1990 C standard with GNU extensions.
2626 Conform to the ISO 1999 C standard with GNU extensions.
2629 C ObjC Alias(std=gnu99)
2630 Deprecated in favor of -std=gnu99.
2633 C ObjC Alias(std=c90)
2634 Conform to the ISO 1990 C standard.
2638 Conform to the ISO 1990 C standard as amended in 1994.
2641 C ObjC Alias(std=c99)
2642 Conform to the ISO 1999 C standard.
2645 C ObjC Alias(std=c99)
2646 Deprecated in favor of -std=iso9899:1999.
2649 C ObjC Alias(std=c11)
2650 Conform to the ISO 2011 C standard.
2653 C ObjC Alias(std=c17)
2654 Conform to the ISO 2017 C standard (published in 2018).
2657 C ObjC Alias(std=c17)
2658 Conform to the ISO 2017 C standard (published in 2018).
2661 C ObjC Alias(std=c23)
2662 Conform to the ISO 2023 C standard draft (expected to be published in 2024) (experimental and incomplete support).
2665 Driver C++ ObjC++ Common Condition(ENABLE_STDLIB_OPTION) Var(flag_stdlib_kind) Joined Enum(stdlib_kind) RejectNegative Init(1)
2666 -stdlib=[libstdc++|libc++] The standard library to be used for C++ headers
2670 Name(stdlib_kind) Type(int)
2673 Enum(stdlib_kind) String(libstdc++) Value(1)
2676 Enum(stdlib_kind) String(libc++) Value(2)
2683 Enable traditional preprocessing.
2687 -trigraphs Support ISO C trigraphs.
2690 C ObjC C++ ObjC++ Var(flag_undef)
2691 Do not predefine system-specific and GCC-specific macros.
2695 ; Documented in common.opt
2699 ; Documented in common.opt
2701 ; This comment is to ensure we retain the blank line above.