1 ; Options for the C, ObjC, C++ and ObjC++ front ends.
2 ; Copyright (C) 2003-2023 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.
261 Do not generate #line directives.
264 C ObjC C++ ObjC++ Joined Separate MissingArgError(macro name missing after %qs)
265 -U<macro> Undefine <macro>.
268 C ObjC C++ ObjC++ LTO Var(warn_nsobject_attribute) Warning Init(1)
269 Warn if the NSObject attribute is applied to a non-typedef.
272 C ObjC C++ ObjC++ LTO Var(warn_abi) Warning
273 Warn about things that will change when compiling with an ABI-compliant compiler.
276 C ObjC C++ ObjC++ LTO Joined RejectNegative UInteger Warning
277 Warn about things that change between the current -fabi-version and the specified version.
280 C++ ObjC++ Var(warn_abi_tag) Warning
281 Warn if a subobject has an abi_tag attribute that the complete object type does not have.
284 C ObjC C++ ObjC++ LTO Var(warn_psabi) Init(1) Warning Undocumented LangEnabledBy(C ObjC C++ ObjC++,Wabi)
287 C ObjC Var(warn_absolute_value) Warning EnabledBy(Wextra)
288 Warn on suspicious calls of standard functions computing absolute values.
291 C ObjC C++ ObjC++ Var(warn_address) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
292 Warn about suspicious uses of memory addresses.
295 Name(warn_aligned_new_level) Type(int) UnknownError(argument %qs to %<-Waligned-new%> not recognized)
298 Enum(warn_aligned_new_level) String(none) Value(0)
301 Enum(warn_aligned_new_level) String(global) Value(1)
304 Enum(warn_aligned_new_level) String(all) Value(2)
307 C++ ObjC++ Alias(Waligned-new=,global,none)
308 Warn about 'new' of type with extended alignment without -faligned-new.
311 C++ ObjC++ Var(warn_aligned_new) Enum(warn_aligned_new_level) Joined RejectNegative Warning LangEnabledBy(C++ ObjC++,Wall,1,0)
312 -Waligned-new=[none|global|all] Warn even if 'new' uses a class member allocation function.
315 C ObjC C++ ObjC++ Warning
316 Enable most warning messages.
319 C ObjC C++ ObjC++ Var(warn_alloca) Warning
320 Warn on any use of alloca.
322 Walloc-size-larger-than=
323 C ObjC C++ LTO ObjC++ Var(warn_alloc_size_limit) Joined Host_Wide_Int ByteSize Warning Init(HOST_WIDE_INT_MAX)
324 -Walloc-size-larger-than=<bytes> Warn for calls to allocation functions that
325 attempt to allocate objects larger than the specified number of bytes.
327 Wno-alloc-size-larger-than
328 C ObjC C++ LTO ObjC++ Alias(Walloc-size-larger-than=,18446744073709551615EiB,none) Warning
329 Disable Walloc-size-larger-than= warning. Equivalent to Walloc-size-larger-than=<SIZE_MAX> or larger.
332 C ObjC C++ ObjC++ Var(warn_alloc_zero) Warning
333 Warn for calls to allocation functions that specify zero bytes.
336 C ObjC C++ LTO ObjC++ Var(warn_alloca_limit) Warning Joined Host_Wide_Int ByteSize Init(HOST_WIDE_INT_MAX)
337 -Walloca-larger-than=<number> Warn on unbounded uses of
338 alloca, and on bounded uses of alloca whose bound can be larger than
341 Wno-alloca-larger-than
342 C ObjC C++ LTO ObjC++ Alias(Walloca-larger-than=,18446744073709551615EiB,none) Warning
343 Disable Walloca-larger-than= warning. Equivalent to Walloca-larger-than=<SIZE_MAX> or larger.
346 LangEnabledBy(C ObjC C++ LTO ObjC++,Wall,1,0)
350 C ObjC C++ ObjC++ Var(warn_array_compare) Warning LangEnabledBy(C ObjC C++ ObjC++, Wall)
351 Warn about comparisons between two operands of array type.
354 C ObjC C++ ObjC++ Warning Alias(Warray-parameter=, 2, 0)
355 Warn about mismatched declarations of array parameters and unsafe accesses to them.
358 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_array_parameter) IntegerRange(0, 2) LangEnabledBy(C ObjC C++ ObjC++,Wall, 2, 0) Warning
359 Warn about mismatched declarations of array parameters and unsafe accesses to them.
362 C ObjC C++ ObjC++ Var(warn_zero_length_bounds) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
363 Warn about accesses to interior zero-length array members.
366 ObjC ObjC++ Var(warn_assign_intercept) Warning
367 Warn whenever an Objective-C assignment is being intercepted by the garbage collector.
370 C ObjC Var(warn_bad_function_cast) Warning
371 Warn about casting functions to incompatible types.
374 C ObjC C++ ObjC++ Warning Alias(Wbidi-chars=,any,none)
378 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
379 -Wbidi-chars=[none|unpaired|any|ucn] Warn about UTF-8 bidirectional control characters.
381 ; Required for these enum values.
386 Name(cpp_bidirectional_level) Type(int) UnknownError(argument %qs to %<-Wbidi-chars%> not recognized)
389 Enum(cpp_bidirectional_level) String(none) Value(bidirectional_none) Set(1)
392 Enum(cpp_bidirectional_level) String(unpaired) Value(bidirectional_unpaired) Set(1)
395 Enum(cpp_bidirectional_level) String(any) Value(bidirectional_any) Set(1)
398 Enum(cpp_bidirectional_level) String(ucn) Value(bidirectional_ucn) Set(2)
401 C ObjC C++ ObjC++ Var(warn_bool_compare) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
402 Warn about boolean expression compared with an integer value different from true/false.
405 C ObjC C++ ObjC++ Var(warn_bool_op) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
406 Warn about certain operations on boolean expressions.
409 C ObjC C++ ObjC++ Var(warn_frame_address) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
410 Warn when __builtin_frame_address or __builtin_return_address is used unsafely.
412 Wbuiltin-declaration-mismatch
413 C ObjC C++ ObjC++ Var(warn_builtin_declaration_mismatch) Init(1) Warning
414 Warn when a built-in function is declared with the wrong signature.
416 Wbuiltin-macro-redefined
417 C ObjC C++ ObjC++ CPP(warn_builtin_macro_redefined) CppReason(CPP_W_BUILTIN_MACRO_REDEFINED) Var(cpp_warn_builtin_macro_redefined) Init(1) Warning
418 Warn when a built-in preprocessor macro is undefined or redefined.
421 C ObjC CPP(cpp_warn_c11_c2x_compat) CppReason(CPP_W_C11_C2X_COMPAT) Var(warn_c11_c2x_compat) Init(-1) Warning
422 Warn about features not present in ISO C11, but present in ISO C2X.
425 C ObjC CPP(cpp_warn_c90_c99_compat) CppReason(CPP_W_C90_C99_COMPAT) Var(warn_c90_c99_compat) Init(-1) Warning
426 Warn about features not present in ISO C90, but present in ISO C99.
429 C ObjC Var(warn_c99_c11_compat) Init(-1) Warning
430 Warn about features not present in ISO C99, but present in ISO C11.
433 C ObjC Var(warn_cxx_compat) CPP(warn_cxx_operator_names) CppReason(CPP_W_CXX_OPERATOR_NAMES) Init(0) Warning
434 Warn about C constructs that are not in the common subset of C and C++.
437 C++ ObjC++ Warning Alias(Wc++11-compat) Undocumented
440 C++ ObjC++ Var(warn_cxx11_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx11_compat) CppReason(CPP_W_CXX11_COMPAT)
441 Warn about C++ constructs whose meaning differs between ISO C++ 1998 and ISO C++ 2011.
444 C++ ObjC++ Var(warn_cxx14_compat) Warning LangEnabledBy(C++ ObjC++,Wall)
445 Warn about C++ constructs whose meaning differs between ISO C++ 2011 and ISO C++ 2014.
448 C++ ObjC++ Warning Alias(Wc++17-compat) Undocumented
451 C++ ObjC++ Var(warn_cxx17_compat) Warning LangEnabledBy(C++ ObjC++,Wall)
452 Warn about C++ constructs whose meaning differs between ISO C++ 2014 and ISO C++ 2017.
455 C++ ObjC++ Warning Alias(Wc++20-compat) Undocumented
458 C++ ObjC++ Var(warn_cxx20_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx20_compat) CppReason(CPP_W_CXX20_COMPAT)
459 Warn about C++ constructs whose meaning differs between ISO C++ 2017 and ISO C++ 2020.
462 C++ ObjC++ Var(warn_cxx11_extensions) Warning Init(1)
463 Warn about C++11 constructs in code compiled with an older standard.
466 C++ ObjC++ Var(warn_cxx14_extensions) Warning Init(1)
467 Warn about C++14 constructs in code compiled with an older standard.
470 C++ ObjC++ Var(warn_cxx17_extensions) Warning Init(1)
471 Warn about C++17 constructs in code compiled with an older standard.
474 C++ ObjC++ Var(warn_cxx20_extensions) Warning Init(1)
475 Warn about C++20 constructs in code compiled with an older standard.
478 C++ ObjC++ Var(warn_cxx23_extensions) Warning Init(1)
479 Warn about C++23 constructs in code compiled with an older standard.
482 C ObjC C++ ObjC++ Var(warn_cast_function_type) Warning EnabledBy(Wextra)
483 Warn about casts between incompatible function types.
486 C ObjC C++ ObjC++ Var(warn_cast_qual) Warning
487 Warn about casts which discard qualifiers.
490 C++ ObjC++ Warning Alias(Wcatch-value=, 1, 0)
491 Warn about catch handlers of non-reference type.
494 C++ ObjC++ Var(warn_catch_value) Warning Joined RejectNegative UInteger LangEnabledBy(C++ ObjC++,Wall, 1, 0) IntegerRange(0, 3)
495 Warn about catch handlers of non-reference type.
498 C++ ObjC++ Var(warn_changes_meaning) Warning Init(1)
499 Complain about a name being declared as a class member after a previous use of the same name.
502 C ObjC C++ ObjC++ Var(warn_char_subscripts) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
503 Warn about subscripts whose type is \"char\".
506 C ObjC C++ ObjC++ Warning WarnRemoved
507 Removed in GCC 9. This switch has no effect.
510 C ObjC C++ ObjC++ Var(warn_clobbered) Warning EnabledBy(Wextra)
511 Warn about variables that might be changed by \"longjmp\" or \"vfork\".
514 C++ ObjC++ Var(warn_comma_subscript) Warning
515 Warn about uses of a comma operator within a subscripting expression.
518 C ObjC C++ ObjC++ CPP(warn_comments) CppReason(CPP_W_COMMENTS) Var(cpp_warn_comment) Init(0) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
519 Warn about possibly nested block comments, and C++ comments spanning more than one physical line.
522 C ObjC C++ ObjC++ Warning Alias(Wcomment)
523 Synonym for -Wcomment.
525 Wconditionally-supported
526 C++ ObjC++ Var(warn_conditionally_supported) Warning
527 Warn for conditionally-supported constructs.
530 C ObjC C++ ObjC++ Var(warn_conversion) Warning
531 Warn for implicit type conversions that may change a value.
534 C++ ObjC++ Var(warn_conversion_null) Init(1) Warning
535 Warn for converting NULL from/to a non-pointer type.
538 C ObjC C++ ObjC++ CppReason(CPP_W_WARNING_DIRECTIVE)
539 ; Documented in common.opt
541 Wctad-maybe-unsupported
542 C++ ObjC++ Var(warn_ctad_maybe_unsupported) Warning
543 Warn when performing class template argument deduction on a type with no
547 C++ ObjC++ Var(warn_ctor_dtor_privacy) Warning
548 Warn when all constructors and destructors are private.
551 C ObjC C++ ObjC++ Var(warn_dangling_else) Warning LangEnabledBy(C ObjC C++ ObjC++,Wparentheses)
552 Warn about dangling else.
555 C ObjC C++ LTO ObjC++ Alias(Wdangling-pointer=, 2, 0) Warning
556 Warn for uses of pointers to auto variables whose lifetime has ended.
559 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_dangling_pointer) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall, 2, 0) IntegerRange(0, 2)
560 Warn for uses of pointers to auto variables whose lifetime has ended.
563 C++ ObjC++ Var(warn_dangling_reference) Warning LangEnabledBy(C++ ObjC++, Wall)
564 Warn when a reference is bound to a temporary whose lifetime has ended.
567 C ObjC C++ ObjC++ CPP(warn_date_time) CppReason(CPP_W_DATE_TIME) Var(cpp_warn_date_time) Init(0) Warning
568 Warn about __TIME__, __DATE__ and __TIMESTAMP__ usage.
570 Wdeclaration-after-statement
571 C ObjC Var(warn_declaration_after_statement) Init(-1) Warning
572 Warn when a declaration is found after a statement.
575 C++ ObjC++ Var(warn_delete_incomplete) Init(1) Warning
576 Warn when deleting a pointer to incomplete type.
578 Wdelete-non-virtual-dtor
579 C++ ObjC++ Var(warn_delnonvdtor) Warning LangEnabledBy(C++ ObjC++,Wall || Weffc++)
580 Warn about deleting polymorphic objects with non-virtual destructors.
583 C C++ ObjC ObjC++ CPP(cpp_warn_deprecated) CppReason(CPP_W_DEPRECATED)
584 ; Documented in common.opt
587 C++ ObjC++ Var(warn_deprecated_copy) Warning LangEnabledBy(C++ ObjC++, Wextra)
588 Mark implicitly-declared copy operations as deprecated if the class has a
589 user-provided copy operation.
591 Wdeprecated-copy-dtor
592 C++ ObjC++ Var(warn_deprecated_copy, 2) Warning
593 Mark implicitly-declared copy operations as deprecated if the class has a
594 user-provided copy operation or destructor.
596 Wdeprecated-enum-enum-conversion
597 C++ ObjC++ Var(warn_deprecated_enum_enum_conv) Warning
598 Warn about deprecated arithmetic conversions on operands of enumeration types.
600 Wdeprecated-enum-float-conversion
601 C++ ObjC++ Var(warn_deprecated_enum_float_conv) Warning
602 Warn about deprecated arithmetic conversions on operands where one is of enumeration
603 type and the other is of a floating-point type.
606 C ObjC Var(warn_designated_init) Init(1) Warning
607 Warn about positional initialization of structs requiring designated initializers.
609 Wdiscarded-array-qualifiers
610 C ObjC Var(warn_discarded_array_qualifiers) Init(1) Warning
611 Warn if qualifiers on arrays which are pointer targets are discarded.
613 Wdiscarded-qualifiers
614 C ObjC Var(warn_discarded_qualifiers) Init(1) Warning
615 Warn if type qualifiers on pointers are discarded.
618 C ObjC C++ ObjC++ Var(warn_div_by_zero) Init(1) Warning
619 Warn about compile-time integer division by zero.
622 C ObjC C++ ObjC++ Var(warn_duplicated_branches) Init(0) Warning
623 Warn about duplicated branches in if-else statements.
626 C ObjC C++ ObjC++ Var(warn_duplicated_cond) Init(0) Warning
627 Warn about duplicated conditions in an if-else-if chain.
630 C++ ObjC++ Var(warn_ecpp) Warning
631 Warn about violations of Effective C++ style rules.
634 C ObjC C++ ObjC++ Var(warn_empty_body) Warning EnabledBy(Wextra)
635 Warn about an empty body in an if or else statement.
638 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)
639 Warn about stray tokens after #else and #endif.
642 C ObjC C++ ObjC++ Var(warn_enum_compare) Init(-1) Warning LangEnabledBy(C ObjC,Wall || Wc++-compat)
643 Warn about comparison of different enum types.
646 C ObjC C++ ObjC++ Var(warn_enum_conversion) Init(0) Warning LangEnabledBy(C ObjC,Wextra)
647 Warn about implicit conversion of enum types.
650 C ObjC Var(warn_enum_int_mismatch) Warning LangEnabledBy(C ObjC,Wall || Wc++-compat)
651 Warn about enum/integer type mismatches.
655 ; Documented in common.opt
657 Werror-implicit-function-declaration
658 C ObjC RejectNegative Warning Alias(Werror=, implicit-function-declaration)
659 This switch is deprecated; use -Werror=implicit-function-declaration instead.
662 C++ ObjC++ Var(warn_exceptions) Init(1) Warning
663 Warn when an exception handler is shadowed by another handler.
666 C ObjC C++ ObjC++ Warning
670 C++ ObjC++ Var(warn_extra_semi) Warning
671 Warn about semicolon after in-class function definition.
674 C ObjC C++ ObjC++ Var(warn_float_conversion) Warning LangEnabledBy(C ObjC C++ ObjC++,Wconversion)
675 Warn for implicit type conversions that cause loss of floating point precision.
678 C ObjC C++ ObjC++ Var(warn_float_equal) Warning
679 Warn if testing floating point numbers for equality.
682 C ObjC C++ ObjC++ Warning Alias(Wformat=, 1, 0)
683 Warn about printf/scanf/strftime/strfmon format string anomalies.
686 C ObjC C++ ObjC++ Var(warn_format_contains_nul) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 1, 0)
687 Warn about format strings that contain NUL bytes.
690 C ObjC C++ ObjC++ Var(warn_format_diag) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 1, 0)
691 Warn about GCC format strings with strings unsuitable for diagnostics.
694 C ObjC C++ ObjC++ Var(warn_format_extra_args) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 1, 0)
695 Warn if passing too many arguments to a function for its format string.
698 C ObjC C++ ObjC++ Var(warn_format_nonliteral) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 2, 0)
699 Warn about format strings that are not literals.
702 C ObjC C++ LTO ObjC++ Warning Alias(Wformat-overflow=, 1, 0) IntegerRange(0, 2)
703 Warn about function calls with format strings that write past the end
704 of the destination region. Same as -Wformat-overflow=1.
707 C ObjC C++ ObjC++ Var(warn_format_security) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=, warn_format >= 2, 0)
708 Warn about possible security problems with format functions.
711 C ObjC C++ ObjC++ Var(warn_format_signedness) Warning
712 Warn about sign differences with format functions.
715 C ObjC C++ LTO ObjC++ Warning Alias(Wformat-truncation=, 1, 0)
716 Warn about calls to snprintf and similar functions that truncate output.
717 Same as -Wformat-truncation=1.
720 C ObjC C++ ObjC++ Var(warn_format_y2k) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=,warn_format >= 2, 0)
721 Warn about strftime formats yielding 2-digit years.
724 C ObjC C++ ObjC++ Var(warn_format_zero_length) Warning LangEnabledBy(C ObjC C++ ObjC++,Wformat=,warn_format >= 1, 0)
725 Warn about zero-length formats.
728 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_format) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0) IntegerRange(0, 2)
729 Warn about printf/scanf/strftime/strfmon format string anomalies.
732 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)
733 Warn about function calls with format strings that write past the end
734 of the destination region.
737 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)
738 Warn about calls to snprintf and similar functions that truncate output.
741 C ObjC C++ ObjC++ Var(warn_if_not_aligned) Init(1) Warning
742 Warn when the field in a struct is not aligned.
745 C C++ Var(warn_ignored_qualifiers) Warning EnabledBy(Wextra)
746 Warn whenever type qualifiers are ignored.
749 C C++ Var(warn_ignored_attributes) Init(1) Warning
750 Warn whenever attributes are ignored.
753 C++ ObjC++ Var(warn_inaccessible_base) Init(1) Warning
754 Warn when a base is inaccessible in derived due to ambiguity.
756 Wincompatible-pointer-types
757 C ObjC Var(warn_incompatible_pointer_types) Init(1) Warning
758 Warn when there is a conversion between pointers that have incompatible types.
761 C ObjC C++ LTO ObjC++ Var(warn_infinite_recursion) Warning LangEnabledBy(C ObjC C++ LTO ObjC++, Wall)
762 Warn for infinitely recursive calls.
764 Waddress-of-packed-member
765 C ObjC C++ ObjC++ Var(warn_address_of_packed_member) Init(1) Warning
766 Warn when the address of packed member of struct or union is taken.
769 C ObjC C++ ObjC++ Var(warn_init_self) Warning LangEnabledBy(C++ ObjC++,Wall)
770 Warn about variables which are initialized to themselves.
773 C++ ObjC++ Var(warn_init_list) Warning Init(1)
774 Warn about uses of std::initializer_list that can result in dangling pointers.
777 C++ ObjC++ Var(warn_interference_size) Warning Init(1)
778 Warn about nonsensical values of --param destructive-interference-size or
779 constructive-interference-size.
782 C ObjC Var(warn_implicit) Warning LangEnabledBy(C ObjC,Wall)
783 Warn about implicit declarations.
785 Wimplicit-fallthrough=
786 LangEnabledBy(C ObjC C++ ObjC++,Wextra,3,0)
790 C ObjC C++ ObjC++ Var(warn_double_promotion) Warning
791 Warn about implicit conversions from \"float\" to \"double\".
793 Wexpansion-to-defined
794 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)
795 Warn if \"defined\" is used outside #if.
797 Wimplicit-function-declaration
798 C ObjC Var(warn_implicit_function_declaration) Init(-1) Warning LangEnabledBy(C ObjC,Wimplicit)
799 Warn about implicit function declarations.
802 C ObjC Var(warn_implicit_int) Init(-1) Warning LangEnabledBy(C ObjC,Wimplicit)
803 Warn when a declaration does not specify a type.
806 C ObjC C++ ObjC++ Undocumented Ignore
808 Winherited-variadic-ctor
809 C++ ObjC++ Var(warn_inh_var_ctor) Init(1) Warning
810 Warn about C++11 inheriting constructors when the base has a variadic constructor.
813 C ObjC Var(warn_int_conversion) Init(1) Warning
814 Warn about incompatible integer to pointer and pointer to integer conversions.
817 C ObjC C++ ObjC++ Var(warn_int_in_bool_context) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
818 Warn for suspicious integer expressions in boolean context.
821 C ObjC C++ ObjC++ Var(warn_int_to_pointer_cast) Init(1) Warning
822 Warn when there is a cast to a pointer from an integer of a different size.
825 C++ ObjC++ Var(warn_invalid_constexpr) Init(-1) Warning
826 Warn when a function never produces a constant expression.
829 C++ ObjC++ Var(warn_invalid_offsetof) Init(1) Warning
830 Warn about invalid uses of the \"offsetof\" macro.
833 C ObjC C++ ObjC++ CPP(warn_invalid_pch) CppReason(CPP_W_INVALID_PCH) Var(cpp_warn_invalid_pch) Init(0) Warning
834 Warn about PCH files that are found but not used.
837 C ObjC C++ ObjC++ CPP(cpp_warn_invalid_utf8) CppReason(CPP_W_INVALID_UTF8) Var(warn_invalid_utf8) Init(0) Warning
838 Warn about invalid UTF-8 characters.
841 C ObjC Var(warn_jump_misses_init) Warning LangEnabledby(C ObjC,Wc++-compat)
842 Warn when a jump misses a variable initialization.
845 C++ ObjC++ CPP(warn_literal_suffix) CppReason(CPP_W_LITERAL_SUFFIX) Var(cpp_warn_literal_suffix) Init(1) Warning
846 Warn when a string or character literal is followed by a ud-suffix which does not begin with an underscore.
849 C ObjC C++ ObjC++ Var(warn_logical_op) Init(0) Warning
850 Warn when a logical operator is suspiciously always evaluating to true or false.
852 Wlogical-not-parentheses
853 C ObjC C++ ObjC++ Var(warn_logical_not_paren) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
854 Warn when logical not is used on the left hand side operand of a comparison.
857 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)
858 Do not warn about using \"long long\" when -pedantic.
861 C ObjC C++ ObjC++ Var(warn_main) Init(-1) Warning LangEnabledBy(C ObjC,Wall, 2, 0)
862 Warn about suspicious declarations of \"main\".
865 LangEnabledBy(C ObjC C++ ObjC++,Wpedantic, 2, 0)
868 Wmemset-transposed-args
869 C ObjC C++ ObjC++ Var(warn_memset_transposed_args) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
870 Warn about suspicious calls to memset where the third argument is constant literal zero and the second is not.
873 C ObjC C++ ObjC++ Var(warn_memset_elt_size) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
874 Warn about suspicious calls to memset where the third argument contains the number of elements not multiplied by the element size.
876 Wmisleading-indentation
877 C C++ Common Var(warn_misleading_indentation) Warning LangEnabledBy(C C++,Wall)
878 Warn when the indentation of the code does not reflect the block structure.
881 C ObjC C++ ObjC++ Var(warn_mismatched_alloc) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
882 Warn for deallocation calls with arguments returned from mismatched allocation
885 Wmismatched-new-delete
886 C++ ObjC++ Var(warn_mismatched_new_delete) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
887 Warn for mismatches between calls to operator new or delete and the corresponding
888 call to the allocation or deallocation function.
891 C++ ObjC++ Var(warn_mismatched_tags) Warning
892 Warn when a class is redeclared or referenced using a mismatched class-key.
895 C ObjC C++ ObjC++ Var(warn_missing_braces) Warning LangEnabledBy(C ObjC,Wall)
896 Warn about possibly missing braces around initializers.
898 Wmissing-declarations
899 C ObjC C++ ObjC++ Var(warn_missing_declarations) Warning
900 Warn about global functions without previous declarations.
902 Wmissing-field-initializers
903 C ObjC C++ ObjC++ Var(warn_missing_field_initializers) Warning EnabledBy(Wextra)
904 Warn about missing fields in struct initializers.
907 C++ ObjC++ Var(warn_missing_requires) Init(1) Warning
908 Warn about likely missing requires keyword.
910 Wmissing-template-keyword
911 C++ ObjC++ Var(warn_missing_template_keyword) Init(1) Warning
912 Warn when the template keyword is missing after a member access token in a dependent member access expression if that member is a template.
914 Wmultistatement-macros
915 C ObjC C++ ObjC++ Var(warn_multistatement_macros) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
916 Warn about unsafe macros expanding to multiple statements used as a body of a clause such as if, else, while, switch, or for.
918 Wmultiple-inheritance
919 C++ ObjC++ Var(warn_multiple_inheritance) Warning
920 Warn on direct multiple inheritance.
923 C++ ObjC++ Var(warn_namespaces) Warning
924 Warn on namespace definition.
927 C ObjC C++ ObjC++ Var(warn_packed_not_aligned) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
928 Warn when fields in a struct with the packed attribute are misaligned.
930 Wrange-loop-construct
931 C++ ObjC++ Var(warn_range_loop_construct) Warning LangEnabledBy(C++ ObjC++,Wall)
932 Warn when a range-based for-loop is creating unnecessary copies.
935 C++ ObjC++ Var(warn_redundant_tags) Warning
936 Warn when a class or enumerated type is referenced using a redundant class-key.
939 C++ ObjC++ Var(warn_sized_deallocation) Warning EnabledBy(Wextra)
940 Warn about missing sized deallocation functions.
943 C ObjC C++ ObjC++ Var(warn_sizeof_pointer_div) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
944 Warn about suspicious divisions of two sizeof expressions that don't work correctly with pointers.
947 C ObjC C++ ObjC++ Var(warn_sizeof_array_div) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
948 Warn about divisions of two sizeof operators when the first one is applied
949 to an array and the divisor does not equal the size of the array element.
951 Wsizeof-pointer-memaccess
952 C ObjC C++ ObjC++ Var(warn_sizeof_pointer_memaccess) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
953 Warn about suspicious length parameters to certain string functions if the argument uses sizeof.
955 Wsizeof-array-argument
956 C ObjC C++ ObjC++ Var(warn_sizeof_array_argument) Warning Init(1)
957 Warn when sizeof is applied on a parameter declared as an array.
960 C ObjC C++ LTO ObjC++ Warning Var(warn_string_compare) Warning LangEnabledBy(C ObjC C++ ObjC++, Wextra)
961 Warn about calls to strcmp and strncmp used in equality expressions that
962 are necessarily true or false due to the length of one and size of the other
966 C ObjC C++ LTO ObjC++ Warning Alias(Wstringop-overflow=, 2, 0)
967 Warn about buffer overflow in string manipulation functions like memcpy
971 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)
972 Under the control of Object Size type, warn about buffer overflow in string
973 manipulation functions like memcpy and strcpy.
976 C ObjC C++ LTO ObjC++ Var(warn_stringop_overread) Init(1) Warning LangEnabledBy(C ObjC C++ LTO ObjC++, Wall)
977 Warn about reading past the end of a source array in string manipulation functions like memchr and memcpy.
980 C ObjC C++ LTO ObjC++ Var(warn_stringop_truncation) Warning Init (1) LangEnabledBy(C ObjC C++ LTO ObjC++, Wall)
981 Warn about truncation in string manipulation functions like strncat and strncpy.
984 C C++ Var(warn_strict_flex_arrays) Warning
985 Warn about inproper usages of flexible array members
986 according to the level of -fstrict-flex-arrays.
988 Wsuggest-attribute=format
989 C ObjC C++ ObjC++ Var(warn_suggest_attribute_format) Warning
990 Warn about functions which might be candidates for format attributes.
993 C++ ObjC++ Var(warn_override) Warning
994 Suggest that the override keyword be used when the declaration of a virtual
995 function overrides another.
998 C ObjC C++ ObjC++ Var(warn_switch) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
999 Warn about enumerated switches, with no default, missing a case.
1002 C ObjC C++ ObjC++ Var(warn_switch_default) Warning
1003 Warn about enumerated switches missing a \"default:\" statement.
1006 C ObjC C++ ObjC++ Var(warn_switch_enum) Warning
1007 Warn about all enumerated switches missing a specific case.
1010 C ObjC C++ ObjC++ Var(warn_switch_bool) Warning Init(1)
1011 Warn about switches with boolean controlling expression.
1013 Wswitch-outside-range
1014 C ObjC C++ ObjC++ Var(warn_switch_outside_range) Warning Init(1)
1015 Warn about switch values that are outside of the switch's type range.
1018 C++ ObjC++ Var(warn_templates) Warning
1019 Warn on primary template declaration.
1022 C ObjC C++ ObjC++ Var(warn_missing_attributes) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1023 Warn about declarations of entities that may be missing attributes
1024 that related entities have been declared with.
1026 Wmissing-format-attribute
1027 C ObjC C++ ObjC++ Warning Alias(Wsuggest-attribute=format)
1030 Wmissing-include-dirs
1031 C ObjC C++ ObjC++ CPP(warn_missing_include_dirs) CppReason(CPP_W_MISSING_INCLUDE_DIRS) Var(cpp_warn_missing_include_dirs) Init(0) Warning
1032 Warn about user-specified include directories that do not exist.
1034 Wmissing-parameter-type
1035 C ObjC Var(warn_missing_parameter_type) Warning EnabledBy(Wextra)
1036 Warn about function parameters declared without a type specifier in K&R-style functions.
1039 C ObjC Var(warn_missing_prototypes) Warning
1040 Warn about global functions without prototypes.
1043 C ObjC C++ ObjC++ WarnRemoved
1046 C ObjC C++ ObjC++ CPP(warn_multichar) CppReason(CPP_W_MULTICHAR) Var(cpp_warn_multichar) Init(0) Warning
1047 Warn about use of multi-character character constants.
1050 C ObjC C++ ObjC++ Warning Var(warn_narrowing) Init(-1) LangEnabledBy(C++ ObjC++,Wall || Wc++11-compat)
1051 Warn about narrowing conversions within { } that are ill-formed in C++11.
1054 C ObjC Var(warn_nested_externs) Warning
1055 Warn about \"extern\" declarations not at file scope.
1058 C++ ObjC++ Var(warn_noexcept) Warning
1059 Warn when a noexcept expression evaluates to false even though the expression can't actually throw.
1062 C++ ObjC++ Warning Var(warn_noexcept_type) LangEnabledBy(C++ ObjC++,Wabi || Wc++17-compat)
1063 Warn if C++17 noexcept function type will change the mangled name of a symbol.
1065 Wnon-template-friend
1066 C++ ObjC++ Var(warn_nontemplate_friend) Init(1) Warning
1067 Warn when non-templatized friend functions are declared within a template.
1070 C++ ObjC++ Var(warn_class_conversion) Init(1) Warning
1071 Warn when a conversion function will never be called due to the type it converts to.
1074 C++ ObjC++ Var(warn_class_memaccess) Warning LangEnabledBy(C++ ObjC++, Wall)
1075 Warn for unsafe raw memory writes to objects of class types.
1078 C++ ObjC++ Var(warn_nonvdtor) Warning LangEnabledBy(C++ ObjC++,Weffc++)
1079 Warn about non-virtual destructors.
1082 C ObjC C++ LTO ObjC++ Var(warn_nonnull) Warning LangEnabledBy(C ObjC C++ LTO ObjC++,Wformat=,warn_format >= 1,0)
1083 Warn about NULL being passed to argument slots marked as requiring non-NULL.
1086 C ObjC C++ LTO ObjC++ LangEnabledBy(C ObjC C++ LTO ObjC++,Wall)
1090 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall)
1094 C ObjC C++ ObjC++ Warning Alias(Wnormalized=,nfc,none)
1098 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)
1099 -Wnormalized=[none|id|nfc|nfkc] Warn about non-normalized Unicode strings.
1101 ; Required for these enum values.
1106 Name(cpp_normalize_level) Type(int) UnknownError(argument %qs to %<-Wnormalized%> not recognized)
1109 Enum(cpp_normalize_level) String(none) Value(normalized_none)
1112 Enum(cpp_normalize_level) String(nfkc) Value(normalized_KC)
1115 Enum(cpp_normalize_level) String(id) Value(normalized_identifier_C)
1118 Enum(cpp_normalize_level) String(nfc) Value(normalized_C)
1121 ObjC ObjC++ Var(warn_objc_root_class) Warning Init(1)
1122 Warn if a class interface has no superclass. Root classes may use an attribute
1123 to suppress this warning.
1126 C++ ObjC++ Var(warn_old_style_cast) Warning
1127 Warn if a C-style cast is used in a program.
1129 Wold-style-declaration
1130 C ObjC Var(warn_old_style_declaration) Warning EnabledBy(Wextra)
1131 Warn for obsolescent usage in a declaration.
1133 Wold-style-definition
1134 C ObjC Var(warn_old_style_definition) Init(-1) Warning
1135 Warn if an old-style parameter definition is used.
1137 Wopenacc-parallelism
1138 C C++ Var(warn_openacc_parallelism) Warning
1139 Warn about potentially suboptimal choices related to OpenACC parallelism.
1142 C C++ Var(warn_openmp_simd) Warning LangEnabledBy(C C++,Wall)
1143 Warn if a simd directive is overridden by the vectorizer cost model.
1146 C ObjC C++ ObjC++ Var(warn_overlength_strings) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic)
1147 Warn if a string is longer than the maximum portable length specified by the standard.
1150 C++ ObjC++ Warning Alias(Woverloaded-virtual=,2,0)
1151 Warn about overloaded virtual function names.
1153 Woverloaded-virtual=
1154 C++ ObjC++ Joined UInteger IntegerRange(0,2) Var(warn_overloaded_virtual) Warning LangEnabledBy(C++ ObjC++,Wall,1,0)
1155 Warn about overloaded virtual function names.
1158 C ObjC Var(warn_override_init) Warning EnabledBy(Wextra)
1159 Warn about overriding initializers without side effects.
1161 Woverride-init-side-effects
1162 C ObjC Var(warn_override_init_side_effects) Init(1) Warning
1163 Warn about overriding initializers with side effects.
1165 Wpacked-bitfield-compat
1166 C ObjC C++ ObjC++ Var(warn_packed_bitfield_compat) Init(-1) Warning
1167 Warn about packed bit-fields whose offset changed in GCC 4.4.
1170 C ObjC C++ ObjC++ Var(warn_parentheses) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1171 Warn about possibly missing parentheses.
1174 C ObjC C++ ObjC++ CPP(cpp_pedantic) CppReason(CPP_W_PEDANTIC) Warning
1175 ; Documented in common.opt
1178 C++ ObjC++ Var(warn_pessimizing_move) Warning LangEnabledBy(C++ ObjC++, Wall)
1179 Warn about calling std::move on a local object in a return statement preventing copy elision.
1182 C++ ObjC++ Var(warn_pmf2ptr) Init(1) Warning
1183 Warn when converting the type of pointers to member functions.
1186 C ObjC C++ ObjC++ Var(warn_pointer_arith) Warning LangEnabledBy(C ObjC C++ ObjC++,Wpedantic)
1187 Warn about function pointer arithmetic.
1190 C ObjC Var(warn_pointer_sign) Warning LangEnabledBy(C ObjC,Wall || Wpedantic)
1191 Warn when a pointer differs in signedness in an assignment.
1194 C ObjC C++ ObjC++ Var(warn_pointer_compare) Init(1) Warning
1195 Warn when a pointer is compared with a zero character constant.
1197 Wpointer-to-int-cast
1198 C ObjC Var(warn_pointer_to_int_cast) Init(1) Warning
1199 Warn when a pointer is cast to an integer of a different size.
1202 C ObjC C++ ObjC++ Var(warn_pragmas) Init(1) Warning
1203 Warn about misuses of pragmas.
1206 C ObjC C++ ObjC++ Var(warn_prio_ctor_dtor) Init(1) Warning
1207 Warn if constructor or destructors with priorities from 0 to 100 are used.
1209 Wproperty-assign-default
1210 ObjC ObjC++ Var(warn_property_assign_default) Init(1) Warning
1211 Warn if a property for an Objective-C object has no assign semantics specified.
1214 ObjC ObjC++ Var(warn_protocol) Init(1) Warning
1215 Warn if inherited methods are unimplemented.
1218 C++ Warning Alias(Wplacement-new=, 1, 0)
1219 Warn for placement new expressions with undefined behavior.
1222 C++ Joined RejectNegative UInteger Var(warn_placement_new) Init(-1) Warning IntegerRange(0, 2)
1223 Warn for placement new expressions with undefined behavior.
1226 C ObjC C++ ObjC++ Var(warn_redundant_decls) Warning
1227 Warn about multiple declarations of the same object.
1230 C++ ObjC++ Var(warn_redundant_move) Warning LangEnabledBy(C++ ObjC++,Wextra)
1231 Warn about redundant calls to std::move.
1234 C++ ObjC++ Var(warn_register) Warning
1235 Warn about uses of register storage specifier.
1238 C++ ObjC++ Var(warn_reorder) Warning LangEnabledBy(C++ ObjC++,Wall)
1239 Warn when the compiler reorders code.
1242 C ObjC C++ ObjC++ Var(warn_return_type) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall) Init(-1)
1243 Warn whenever a function's return type defaults to \"int\" (C), or about inconsistent return types (C++).
1245 Wscalar-storage-order
1246 C ObjC C++ ObjC++ Var(warn_scalar_storage_order) Init(1) Warning
1247 Warn on suspicious constructs involving reverse scalar storage order.
1250 ObjC ObjC++ Var(warn_selector) Warning
1251 Warn if a selector has multiple methods.
1254 C++ ObjC++ Var(warn_self_move) Warning LangEnabledBy(C++ ObjC++, Wall)
1255 Warn when a value is moved to itself with std::move.
1258 C ObjC C++ ObjC++ Var(warn_sequence_point) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1259 Warn about possible violations of sequence point rules.
1262 ObjC ObjC++ Var(warn_shadow_ivar) EnabledBy(Wshadow) Init(1) Warning
1263 Warn if a local declaration hides an instance variable.
1266 C ObjC C++ ObjC++ Warning Alias(Wshift-overflow=, 1, 0)
1267 Warn if left shift of a signed value overflows.
1270 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_shift_overflow) Init(-1) Warning IntegerRange(0, 2)
1271 Warn if left shift of a signed value overflows.
1273 Wshift-count-negative
1274 C ObjC C++ ObjC++ Var(warn_shift_count_negative) Init(1) Warning
1275 Warn if shift count is negative.
1277 Wshift-count-overflow
1278 C ObjC C++ ObjC++ Var(warn_shift_count_overflow) Init(1) Warning
1279 Warn if shift count >= width of type.
1281 Wshift-negative-value
1282 C ObjC C++ ObjC++ Var(warn_shift_negative_value) Init(-1) Warning
1283 Warn if left shifting a negative value.
1286 C ObjC C++ ObjC++ Var(warn_arith_conv) Warning
1287 Warn if conversion of the result of arithmetic might change the value even though converting the operands cannot.
1290 C ObjC C++ ObjC++ Var(warn_sign_compare) Warning LangEnabledBy(C++ ObjC++,Wall)
1291 Warn about signed-unsigned comparisons.
1294 C ObjC C++ ObjC++ EnabledBy(Wextra)
1298 C ObjC C++ ObjC++ Var(warn_sign_conversion) Warning LangEnabledBy(C ObjC,Wconversion)
1299 Warn for implicit type conversions between signed and unsigned integers.
1302 C++ ObjC++ Var(warn_sign_promo) Warning
1303 Warn when overload promotes from unsigned to signed.
1305 Wstrict-null-sentinel
1306 C++ ObjC++ Warning Var(warn_strict_null_sentinel)
1307 Warn about uncasted NULL used as sentinel.
1310 C ObjC Var(warn_strict_prototypes) Warning
1311 Warn about unprototyped function declarations.
1314 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall, 3, 0) IntegerRange(0, 3)
1318 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0) IntegerRange(0, 5)
1321 Wstrict-selector-match
1322 ObjC ObjC++ Var(warn_strict_selector_match) Warning
1323 Warn if type signatures of candidate methods do not match exactly.
1326 C C++ Var(warn_sync_nand) Init(1) Warning
1327 Warn when __sync_fetch_and_nand and __sync_nand_and_fetch built-in functions are used.
1330 C++ ObjC++ Var(warn_synth) Warning
1331 Deprecated. This switch has no effect.
1334 C ObjC C++ ObjC++ Warning
1335 ; Documented in common.opt
1337 Wtautological-compare
1338 C ObjC C++ ObjC++ Var(warn_tautological_compare) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1339 Warn if a comparison always evaluates to true or false.
1342 C++ ObjC++ Warning Var(warn_terminate) Init(1)
1343 Warn if a throw expression will always result in a call to terminate().
1346 C ObjC CPP(cpp_warn_traditional) CppReason(CPP_W_TRADITIONAL) Var(warn_traditional) Init(0) Warning
1347 Warn about features not present in traditional C.
1349 Wtraditional-conversion
1350 C ObjC Var(warn_traditional_conversion) Warning
1351 Warn of prototypes causing type conversions different from what would happen in the absence of prototype.
1354 C ObjC C++ ObjC++ CPP(warn_trigraphs) CppReason(CPP_W_TRIGRAPHS) Var(cpp_warn_trigraphs) Init(2) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1355 Warn if trigraphs are encountered that might affect the meaning of the program.
1357 Wundeclared-selector
1358 ObjC ObjC++ Var(warn_undeclared_selector) Warning
1359 Warn about @selector()s without previously declared methods.
1362 C ObjC C++ ObjC++ CPP(warn_undef) CppReason(CPP_W_UNDEF) Var(cpp_warn_undef) Init(0) Warning
1363 Warn if an undefined macro is used in an #if directive.
1366 C ObjC C++ ObjC++ CPP(cpp_warn_unicode) CppReason(CPP_W_UNICODE) Var(warn_unicode) Init(1) Warning
1367 Warn about invalid forms of delimited or named escape sequences.
1370 C ObjC C++ ObjC++ LTO LangEnabledBy(C ObjC C++ ObjC++ LTO,Wall)
1373 Wmaybe-uninitialized
1374 C ObjC C++ ObjC++ LTO LangEnabledBy(C ObjC C++ ObjC++ LTO,Wall)
1378 C ObjC C++ ObjC++ Warning Var(warn_unknown_pragmas) LangEnabledBy(C ObjC C++ ObjC++,Wall, 1, 0)
1379 Warn about unrecognized pragmas.
1381 Wunsuffixed-float-constants
1382 C ObjC Var(warn_unsuffixed_float_constants) Warning
1383 Warn about unsuffixed float constants.
1386 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wall)
1387 ; documented in common.opt
1389 Wunused-local-typedefs
1390 C ObjC C++ ObjC++ Var(warn_unused_local_typedefs) Warning EnabledBy(Wunused)
1391 Warn when typedefs locally defined in a function are not used.
1394 C ObjC C++ ObjC++ CppReason(CPP_W_UNUSED_MACROS) Var(cpp_warn_unused_macros) Warning
1395 Warn about macros defined in the main file that are not used.
1398 C ObjC C++ ObjC++ Var(warn_unused_result) Init(1) Warning
1399 Warn if a caller of a function, marked with attribute warn_unused_result, does not use its return value.
1402 C ObjC C++ ObjC++ LangEnabledBy(C ObjC C++ ObjC++,Wunused)
1403 ; documented in common.opt
1405 Wunused-const-variable
1406 C ObjC C++ ObjC++ Warning Alias(Wunused-const-variable=, 2, 0)
1407 Warn when a const variable is unused.
1409 Wunused-const-variable=
1410 C ObjC C++ ObjC++ Joined RejectNegative UInteger Var(warn_unused_const_variable) Warning LangEnabledBy(C ObjC,Wunused-variable, 1, 0) IntegerRange(0, 2)
1411 Warn when a const variable is unused.
1413 ; Defining this option here in addition to common.opt is necessary
1414 ; in order for the default -Wall setting of -Wuse-after-free=2 to take
1418 LangEnabledBy(C ObjC C++ LTO ObjC++, Wall,2,0)
1422 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)
1423 Warn about using variadic macros.
1426 C ObjC C++ ObjC++ Warning Var(warn_varargs) Init(1)
1427 Warn about questionable usage of the macros used to retrieve variable arguments.
1430 C++ ObjC++ Warning Var(warn_vexing_parse) Init(1)
1431 Warn about the most vexing parse syntactic ambiguity.
1434 C ObjC C++ ObjC++ Var(warn_vla) Init(-1) Warning
1435 Warn if a variable length array is used.
1438 C ObjC C++ LTO ObjC++ Var(warn_vla_limit) Warning Joined Host_Wide_Int ByteSize Init(HOST_WIDE_INT_MAX)
1439 -Wvla-larger-than=<number> Warn on unbounded uses of variable-length
1440 arrays, and on bounded uses of variable-length arrays whose bound can be
1441 larger than <number> bytes.
1444 C ObjC C++ LTO ObjC++ Alias(Wvla-larger-than=,18446744073709551615EiB,none) Warning
1445 Disable Wvla-larger-than= warning. Equivalent to Wvla-larger-than=<SIZE_MAX> or larger.
1448 C ObjC C++ ObjC++ Var(warn_vla_parameter) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1449 Warn about mismatched declarations of VLA parameters.
1452 C++ ObjC++ Var(warn_volatile) Warning
1453 Warn about deprecated uses of volatile qualifier.
1455 Wvolatile-register-var
1456 C ObjC C++ ObjC++ Var(warn_volatile_register_var) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall)
1457 Warn when a register variable is declared volatile.
1459 Wvirtual-inheritance
1460 C++ ObjC++ Var(warn_virtual_inheritance) Warning
1461 Warn on direct virtual inheritance.
1463 Wvirtual-move-assign
1464 C++ ObjC++ Var(warn_virtual_move_assign) Warning Init(1)
1465 Warn if a virtual base has a non-trivial move assignment operator.
1468 C ObjC C++ ObjC++ Var(warn_write_strings) Warning
1469 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.
1472 C ObjC C++ ObjC++ Var(warn_xor_used_as_pow) Warning Init(1)
1473 Warn about xor operators where it appears the user meant exponentiation.
1475 Wzero-as-null-pointer-constant
1476 C++ ObjC++ Var(warn_zero_as_null_pointer_constant) Warning
1477 Warn when a literal '0' is used as null pointer.
1480 C++ ObjC++ Var(warn_useless_cast) Warning
1481 Warn about useless casts.
1484 C++ ObjC++ Var(warn_subobject_linkage) Warning Init(1)
1485 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.
1487 Wduplicate-decl-specifier
1488 C ObjC Var(warn_duplicate_decl_specifier) Warning LangEnabledBy(C ObjC,Wall)
1489 Warn when a declaration has duplicate const, volatile, restrict or _Atomic specifier.
1492 C ObjC C++ ObjC++ Var(warn_restrict) Warning LangEnabledBy(C ObjC C++ ObjC++, Wall)
1493 Warn when an argument passed to a restrict-qualified parameter aliases with
1498 A synonym for -std=c89 (for C) or -std=c++98 (for C++).
1501 C ObjC C++ ObjC++ Joined
1502 ; Documented in common.opt. FIXME - what about -dI, -dD, -dN and -dD?
1504 fabi-compat-version=
1505 C++ ObjC++ Joined RejectNegative UInteger Var(flag_abi_compat_version) Init(-1)
1506 The version of the C++ ABI used for -Wabi warnings and link compatibility aliases.
1509 C++ ObjC++ Var(flag_access_control) Init(1)
1510 Enforce class member access control semantics.
1513 C ObjC C++ ObjC++ RejectNegative Joined Var(ada_specs_parent)
1514 -fada-spec-parent=unit Dump Ada specs as child units of given parent.
1517 C++ ObjC++ Alias(faligned-new=,1,0)
1518 Support C++17 allocation of over-aligned types.
1521 C++ ObjC++ Joined RejectNegative Var(aligned_new_threshold) UInteger Init(-1)
1522 -faligned-new=<N> Use C++17 over-aligned type allocation for alignments greater than N.
1525 C++ ObjC++ WarnRemoved
1527 fallow-parameterless-variadic-functions
1529 Does nothing. Preserved for backward compatibility.
1531 falt-external-templates
1532 C++ ObjC++ WarnRemoved
1533 No longer supported.
1536 C ObjC C++ ObjC++ Var(flag_no_asm, 0)
1537 Recognize the \"asm\" keyword.
1539 ; Define extra predefined macros for use in libgcc.
1541 C ObjC C++ ObjC++ Undocumented Var(flag_building_libgcc)
1544 C ObjC C++ ObjC++ Var(flag_no_builtin, 0)
1545 Recognize built-in functions.
1548 C ObjC C++ ObjC++ Joined
1550 fcanonical-system-headers
1552 Where shorter, use canonicalized paths to systems headers.
1555 C++ ObjC++ Var(flag_char8_t) Init(-1)
1556 Enable the char8_t fundamental type and use it as the type for UTF-8 string
1557 and character literals.
1559 fcheck-pointer-bounds
1560 C ObjC C++ ObjC++ LTO WarnRemoved
1561 Removed in GCC 9. This switch has no effect.
1563 fchkp-check-incomplete-type
1564 C ObjC C++ ObjC++ LTO WarnRemoved
1565 Removed in GCC 9. This switch has no effect.
1567 fchkp-zero-input-bounds-for-main
1568 C ObjC C++ ObjC++ LTO WarnRemoved
1569 Removed in GCC 9. This switch has no effect.
1571 fchkp-first-field-has-own-bounds
1572 C ObjC C++ ObjC++ LTO WarnRemoved RejectNegative
1573 Removed in GCC 9. This switch has no effect.
1576 C ObjC C++ ObjC++ LTO WarnRemoved
1577 Removed in GCC 9. This switch has no effect.
1579 fchkp-narrow-to-innermost-array
1580 C ObjC C++ ObjC++ LTO WarnRemoved RejectNegative
1581 Removed in GCC 9. This switch has no effect.
1583 fchkp-flexible-struct-trailing-arrays
1584 C ObjC C++ ObjC++ LTO WarnRemoved
1585 Removed in GCC 9. This switch has no effect.
1588 C ObjC C++ ObjC++ LTO WarnRemoved
1590 fchkp-use-fast-string-functions
1591 C ObjC C++ ObjC++ LTO WarnRemoved
1592 Removed in GCC 9. This switch has no effect.
1594 fchkp-use-nochk-string-functions
1595 C ObjC C++ ObjC++ LTO WarnRemoved
1596 Removed in GCC 9. This switch has no effect.
1598 fchkp-use-static-bounds
1599 C ObjC C++ ObjC++ LTO WarnRemoved
1600 Removed in GCC 9. This switch has no effect.
1602 fchkp-use-static-const-bounds
1603 C ObjC C++ ObjC++ LTO WarnRemoved
1604 Removed in GCC 9. This switch has no effect.
1606 fchkp-treat-zero-dynamic-size-as-infinite
1607 C ObjC C++ ObjC++ LTO WarnRemoved
1608 Removed in GCC 9. This switch has no effect.
1611 C ObjC C++ ObjC++ LTO WarnRemoved
1612 Removed in GCC 9. This switch has no effect.
1615 C ObjC C++ ObjC++ LTO WarnRemoved
1616 Removed in GCC 9. This switch has no effect.
1619 C ObjC C++ ObjC++ LTO WarnRemoved
1620 Removed in GCC 9. This switch has no effect.
1622 fchkp-instrument-calls
1623 C ObjC C++ ObjC++ LTO WarnRemoved
1624 Removed in GCC 9. This switch has no effect.
1626 fchkp-instrument-marked-only
1627 C ObjC C++ ObjC++ LTO WarnRemoved
1628 Removed in GCC 9. This switch has no effect.
1631 C ObjC C++ ObjC++ LTO WarnRemoved
1632 Removed in GCC 9. This switch has no effect.
1636 Removed in GCC 9. This switch has no effect.
1638 static-libmpxwrappers
1640 Removed in GCC 9. This switch has no effect.
1643 C ObjC C++ ObjC++ LTO Undocumented Ignore
1644 Removed in GCC 8. This switch has no effect.
1647 C++ ObjC++ Var(flag_concepts)
1648 Enable support for C++ concepts.
1651 C++ ObjC++ Var(flag_concepts_ts) Init(0)
1652 Enable certain features present in the Concepts TS.
1654 fconcepts-diagnostics-depth=
1655 C++ ObjC++ Joined RejectNegative UInteger Var(concepts_diagnostics_max_depth) Init(1)
1656 Specify maximum error replay depth during recursive diagnosis of a constraint satisfaction failure.
1660 Allow the arguments of the '?' operator to have different types.
1664 Does nothing. Preserved for backward compatibility.
1666 fconstant-string-class=
1667 ObjC ObjC++ Joined MissingArgError(no class name specified with %qs)
1668 -fconst-string-class=<name> Use class <name> for constant strings.
1671 C++ ObjC++ Joined RejectNegative UInteger Var(max_constexpr_depth) Init(512)
1672 -fconstexpr-depth=<number> Specify maximum constexpr recursion depth.
1674 fconstexpr-cache-depth=
1675 C++ ObjC++ Joined RejectNegative UInteger Var(constexpr_cache_depth) Init(8)
1676 -fconstexpr-cache-depth=<number> Specify maximum constexpr recursion cache depth.
1678 fconstexpr-fp-except
1679 C++ ObjC++ Var(flag_constexpr_fp_except) Init(0)
1680 Allow IEC559 floating point exceptions in constant expressions.
1682 fconstexpr-loop-limit=
1683 C++ ObjC++ Joined RejectNegative UInteger Var(constexpr_loop_limit) Init(262144)
1684 -fconstexpr-loop-limit=<number> Specify maximum constexpr loop iteration count.
1686 fconstexpr-ops-limit=
1687 C++ ObjC++ Joined RejectNegative Host_Wide_Int Var(constexpr_ops_limit) Init(33554432)
1688 -fconstexpr-ops-limit=<number> Specify maximum number of constexpr operations during a single constexpr evaluation.
1691 C++ ObjC++ Var(flag_contracts) Init(0)
1692 Enable certain features present in drafts of C++ Contracts.
1695 Name(on_off) Type(int) UnknownError(argument %qs must be either %<on%> or %<off%>)
1698 Enum(on_off) String(off) Value(0)
1701 Enum(on_off) String(on) Value(1)
1703 fcontract-assumption-mode=
1704 C++ Joined RejectNegative
1705 -fcontract-assumption-mode=[on|off] Enable or disable treating axiom level contracts as assumptions (default on).
1707 fcontract-build-level=
1708 C++ Joined RejectNegative
1709 -fcontract-build-level=[off|default|audit] Specify max contract level to generate runtime checks for.
1711 fcontract-strict-declarations=
1712 C++ Var(flag_contract_strict_declarations) Enum(on_off) Joined Init(0) RejectNegative
1713 -fcontract-strict-declarations=[on|off] Enable or disable warnings on generalized redeclaration of functions with contracts (default off).
1716 C++ Var(flag_contract_mode) Enum(on_off) Joined Init(1) RejectNegative
1717 -fcontract-mode=[on|off] Enable or disable all contract facilities (default on).
1719 fcontract-continuation-mode=
1720 C++ Joined RejectNegative
1721 -fcontract-continuation-mode=[on|off] Enable or disable contract continuation mode (default off).
1724 C++ Joined RejectNegative
1725 -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).
1728 C++ Joined RejectNegative
1729 -fcontract-semantic=<level>:<semantic> Specify the concrete semantics for level.
1732 C++ LTO Var(flag_coroutines)
1733 Enable C++ coroutines (experimental).
1737 Emit debug annotations during preprocessing.
1741 Does nothing. Preserved for backward compatibility.
1744 C++ ObjC++ Var(flag_declone_ctor_dtor) Init(-1)
1745 Factor complex constructors and destructors to favor space over speed.
1749 Does nothing. Preserved for backward compatibility.
1751 fdiagnostics-show-template-tree
1752 C++ ObjC++ Var(flag_diagnostics_show_template_tree) Init(0)
1753 Print hierarchical comparisons when template types are mismatched.
1757 Preprocess directives only.
1759 fdollars-in-identifiers
1761 Permit '$' as an identifier character.
1764 C ObjC C++ ObjC++ Joined RejectNegative
1765 -fmacro-prefix-map=<old>=<new> Map one directory name to another in __FILE__, __BASE_FILE__, and __builtin_FILE().
1768 C ObjC C++ ObjC++ RejectNegative Var(flag_dump_ada_spec)
1769 Write all declarations as Ada code transitively.
1772 C ObjC C++ ObjC++ RejectNegative Var(flag_dump_ada_spec_slim)
1773 Write all declarations as Ada code for the given file only.
1776 C++ ObjC++ Var(flag_elide_constructors) Init(1)
1779 C++ ObjC++ Var(flag_elide_type) Init(1)
1780 Do not elide common elements in template comparisons.
1783 C++ ObjC++ Var(flag_enforce_eh_specs) Init(1)
1784 Generate code to check exception specifications.
1787 C++ ObjC++ WarnRemoved
1790 C ObjC C++ ObjC++ Joined RejectNegative
1791 -fexec-charset=<cset> Convert all strings and character constants to character set <cset>.
1793 fextended-identifiers
1795 Permit universal character names (\\u and \\U) in identifiers.
1798 C ObjC C++ ObjC++ Joined RejectNegative
1799 -finput-charset=<cset> Specify the default character set for source files.
1802 C++ ObjC++ Var(flag_extern_tls_init) Init(-1)
1803 Support dynamic initialization of thread-local variables in a different translation unit.
1806 C++ ObjC++ WarnRemoved
1808 ffold-simple-inlines
1809 C++ ObjC++ Optimization Var(flag_fold_simple_inlines)
1810 Fold calls to simple inline functions.
1813 C++ ObjC++ WarnRemoved
1817 Do not assume that standard C libraries and \"main\" exist.
1820 C++ ObjC++ Var(flag_no_gnu_keywords, 0)
1821 Recognize GNU-defined keywords.
1824 ObjC ObjC++ LTO RejectNegative Var(flag_next_runtime,0) Init(NEXT_OBJC_RUNTIME)
1825 Generate code for GNU runtime environment.
1828 C ObjC Var(flag_gnu89_inline) Init(-1)
1829 Use traditional GNU semantics for inline functions.
1832 C++ ObjC++ WarnRemoved
1835 C++ ObjC++ Optimization Alias(fexceptions) Warn({%<-fhandle-exceptions%> has been renamed %<-fexceptions%> (and is now on by default)})
1838 C++ ObjC++ WarnRemoved
1842 Assume normal C execution environment.
1845 C++ ObjC++ WarnRemoved
1846 No longer supported.
1849 C++ ObjC++ Var(flag_implement_inlines) Init(1)
1850 Export functions even if they can be inlined.
1853 C++ ObjC++ Var(flag_implicit_constexpr)
1854 Make inline functions constexpr by default.
1856 fimplicit-inline-templates
1857 C++ ObjC++ Var(flag_implicit_inline_templates) Init(1)
1858 Emit implicit instantiations of inline templates.
1861 C++ ObjC++ Var(flag_implicit_templates) Init(1)
1862 Emit implicit instantiations of templates.
1864 fnew-inheriting-ctors
1865 C++ ObjC++ Var(flag_new_inheriting_ctors) Init(1)
1866 Implement C++17 inheriting constructor semantics.
1869 C++ ObjC++ WarnRemoved
1871 fkeep-inline-dllexport
1872 C C++ ObjC ObjC++ Var(flag_keep_inline_dllexport) Init(1) Condition(TARGET_DLLIMPORT_DECL_ATTRIBUTES)
1873 Don't emit dllexported inline functions unless needed.
1876 C++ ObjC++ WarnRemoved
1878 flax-vector-conversions
1879 C ObjC C++ ObjC++ Var(flag_lax_vector_conversions)
1880 Allow implicit conversions between vectors with differing numbers of subparts and/or differing element types.
1883 C++ ObjC++ Var(flag_modules) Integer Init(0)
1884 Enable C++ modules-ts (experimental).
1887 C++ ObjC++ Undocumented RejectNegative Var(flag_modules,0) Integer
1891 C++ ObjC RejectNegative Var(flag_header_unit,0) Integer
1892 Enable C++ header module (experimental).
1895 C++ ObjC++ Joined RejectNegative Undocumented
1897 fmodule-implicit-inline
1898 C++ ObjC++ Var(flag_module_implicit_inline,0) Integer
1899 Member functions defined within their class are inline in module purview.
1902 C++ ObjC RejectNegative Var(flag_module_only) Integer
1903 Only emit Compiled Module Interface.
1906 C++ ObjC++ Joined RejectNegative MissingArgError(missing mapper)
1907 Mapper for module to CMI files.
1910 C++ ObjC++ Var(flag_module_lazy) Init(1)
1911 Enable lazy module importing.
1913 fmodule-version-ignore
1914 C++ ObjC Var(flag_module_version_ignore) Integer
1915 ; undocumented, Very dangerous, but occasionally useful
1917 Winvalid-imported-macros
1918 C++ ObjC++ Var(warn_imported_macros) Warning
1919 Warn about macros that have conflicting header units definitions.
1921 flang-info-include-translate
1922 C++ Var(note_include_translate_yes)
1923 Note #include directives translated to import declarations.
1925 flang-info-include-translate-not
1926 C++ Var(note_include_translate_no)
1927 Note #include directives not translated to import declarations, and not known to be textual.
1929 flang-info-include-translate=
1930 C++ Joined RejectNegative MissingArgError(missing header name)
1931 Note a #include translation of a specific header.
1933 flang-info-module-cmi
1934 C++ Var(note_module_cmi_yes)
1935 Note Compiled Module Interface pathnames.
1937 flang-info-module-cmi=
1938 C++ Joined RejectNegative MissingArgError(missing module name)
1939 Note Compiled Module Interface pathname of a specific module or header-unit.
1942 C ObjC C++ ObjC++ Joined RejectNegative UInteger
1943 fmax-include-depth=<number> Set the maximum depth of the nested #include.
1946 C ObjC C++ ObjC++ Var(flag_ms_extensions)
1947 Don't warn about uses of Microsoft extensions.
1950 C ObjC C++ ObjC++ WarnRemoved
1953 C ObjC C++ ObjC++ WarnRemoved
1956 C ObjC C++ ObjC++ WarnRemoved
1958 fname-mangling-version-
1959 C++ ObjC++ Joined WarnRemoved
1962 C++ ObjC++ WarnRemoved
1965 C++ ObjC++ Var(flag_new_ttp)
1966 Implement resolution of DR 150 for matching of template template arguments.
1969 ObjC ObjC++ LTO RejectNegative Var(flag_next_runtime)
1970 Generate code for NeXT (Apple Mac OS X) runtime environment.
1973 ObjC ObjC++ Var(flag_nil_receivers) Init(1)
1974 Assume that receivers of Objective-C messages may be nil.
1977 ObjC ObjC++ Var(flag_local_ivars) Init(1)
1978 Allow access to instance variables as if they were local declarations within instance method implementations.
1981 ObjC ObjC++ Joined RejectNegative Enum(ivar_visibility) Var(default_ivar_visibility) Init(IVAR_VISIBILITY_PROTECTED)
1982 -fvisibility=[private|protected|public|package] Set the default symbol visibility.
1985 Name(ivar_visibility) Type(enum ivar_visibility) UnknownError(unrecognized ivar visibility value %qs)
1988 Enum(ivar_visibility) String(private) Value(IVAR_VISIBILITY_PRIVATE)
1991 Enum(ivar_visibility) String(protected) Value(IVAR_VISIBILITY_PROTECTED)
1994 Enum(ivar_visibility) String(public) Value(IVAR_VISIBILITY_PUBLIC)
1997 Enum(ivar_visibility) String(package) Value(IVAR_VISIBILITY_PACKAGE)
2000 C++ ObjC++ Var(flag_no_nonansi_builtin, 0)
2003 C++ ObjC++ WarnRemoved
2006 C++ ObjC++ Optimization Var(flag_nothrow_opt)
2007 Treat a throw() exception specification as noexcept to improve code size.
2010 ObjC ObjC++ LTO Joined RejectNegative UInteger Var(flag_objc_abi)
2011 Specify which ABI to use for Objective-C family code and meta-data generation.
2013 ; Generate special '- .cxx_construct' and '- .cxx_destruct' methods
2014 ; to initialize any non-POD ivars in Objective-C++ classes.
2015 fobjc-call-cxx-cdtors
2016 ObjC++ Var(flag_objc_call_cxx_cdtors)
2017 Generate special Objective-C methods to initialize/destroy non-POD C++ ivars, if needed.
2019 fobjc-direct-dispatch
2020 ObjC ObjC++ Var(flag_objc_direct_dispatch)
2021 Allow fast jumps to the message dispatcher.
2023 ; Nonzero means that we will allow new ObjC exception syntax (@throw,
2024 ; @try, etc.) in source code.
2026 ObjC ObjC++ Var(flag_objc_exceptions)
2027 Enable Objective-C exception and synchronization syntax.
2030 ObjC ObjC++ LTO Var(flag_objc_gc)
2031 Enable garbage collection (GC) in Objective-C/Objective-C++ programs.
2034 ObjC ObjC++ Var(flag_objc_nilcheck,1)
2035 Enable inline checks for nil receivers with the NeXT runtime and ABI version 2.
2037 ; Nonzero means that we generate NeXT setjmp based exceptions.
2038 fobjc-sjlj-exceptions
2039 ObjC ObjC++ Var(flag_objc_sjlj_exceptions) Init(-1)
2040 Enable Objective-C setjmp exception handling runtime.
2043 ObjC ObjC++ Var(flag_objc1_only)
2044 Conform to the Objective-C 1.0 language as implemented in GCC 4.0.
2047 C ObjC C++ ObjC++ LTO Var(flag_openacc)
2051 C ObjC C++ ObjC++ LTO Joined Var(flag_openacc_dims)
2052 Specify default OpenACC compute dimensions.
2055 C ObjC C++ ObjC++ LTO Var(flag_openmp)
2056 Enable OpenMP (implies -frecursive in Fortran).
2059 C ObjC C++ ObjC++ Var(flag_openmp_simd)
2060 Enable OpenMP's SIMD directives.
2064 Recognize C++ keywords like \"compl\" and \"xor\".
2068 Does nothing. Preserved for backward compatibility.
2075 Look for and use PCH files even when preprocessing.
2078 C++ ObjC++ Var(flag_permissive)
2079 Downgrade conformance errors to warnings.
2082 C ObjC Var(flag_plan9_extensions)
2083 Enable Plan 9 language extensions.
2087 Treat the input file as already preprocessed.
2089 ftrack-macro-expansion
2090 C ObjC C++ ObjC++ JoinedOrMissing RejectNegative UInteger
2091 ; converted into ftrack-macro-expansion=
2093 ftrack-macro-expansion=
2094 C ObjC C++ ObjC++ JoinedOrMissing RejectNegative UInteger
2095 -ftrack-macro-expansion=<0|1|2> Track locations of tokens coming from macro expansion and display them in error messages.
2098 C++ ObjC++ Var(flag_pretty_templates) Init(1)
2099 Do not pretty-print template specializations as the template signature followed by the arguments.
2101 fprintf-return-value
2102 C ObjC C++ ObjC++ LTO Optimization Var(flag_printf_return_value) Init(1)
2103 Treat known sprintf return values as constants.
2105 freplace-objc-classes
2106 ObjC ObjC++ LTO Var(flag_replace_objc_classes)
2107 Used in Fix-and-Continue mode to indicate that object files may be swapped in at runtime.
2110 C++ ObjC++ WarnRemoved
2111 Removed in GCC 10. This switch has no effect.
2114 C++ ObjC++ Optimization Var(flag_rtti) Init(1)
2115 Generate run time type descriptor information.
2118 C ObjC C++ ObjC++ LTO Optimization Var(flag_short_enums)
2119 Use the narrowest integer type possible for enumeration types.
2122 C ObjC C++ ObjC++ LTO Optimization Var(flag_short_wchar)
2123 Force the underlying type for \"wchar_t\" to be \"unsigned short\".
2126 C ObjC C++ ObjC++ Var(flag_signed_bitfields) Init(1)
2127 When \"signed\" or \"unsigned\" is not given make the bitfield signed.
2130 C ObjC C++ ObjC++ LTO Var(flag_signed_char)
2131 Make \"char\" signed by default.
2134 C++ ObjC++ Var(flag_sized_deallocation) Init(-1)
2135 Enable C++14 sized deallocation support.
2138 C C++ Common Alias(fstrict-flex-arrays=,3,0)
2140 fstrict-flex-arrays=
2141 C C++ Common Joined RejectNegative UInteger Var(flag_strict_flex_arrays) Init(0) IntegerRange(0,3)
2142 -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.
2145 C++ ObjC++ WarnRemoved
2148 C ObjC Joined RejectNegative Enum(sso_struct) Var(default_sso) Init(SSO_NATIVE)
2149 -fsso-struct=[big-endian|little-endian|native] Set the default scalar storage order.
2152 Name(sso_struct) Type(enum scalar_storage_order_kind) UnknownError(unrecognized scalar storage order value %qs)
2155 Enum(sso_struct) String(big-endian) Value(SSO_BIG_ENDIAN)
2158 Enum(sso_struct) String(little-endian) Value(SSO_LITTLE_ENDIAN)
2161 Enum(sso_struct) String(native) Value(SSO_NATIVE)
2164 C++ ObjC++ Var(flag_detailed_statistics)
2165 Display statistics accumulated during compilation.
2168 C++ ObjC++ Optimization Var(flag_strict_enums)
2169 Assume that values of enumeration type are always within the minimum range of that type.
2172 C++ ObjC++ WarnRemoved
2175 C++ ObjC++ Common Alias(fstrong-eval-order=, all, none)
2176 Follow the C++17 evaluation order requirements for assignment expressions,
2177 shift, member function calls, etc.
2180 C++ ObjC++ Common Var(flag_strong_eval_order) Joined Enum(strong_eval_order) RejectNegative Init(-1)
2181 Follow the C++17 evaluation order requirements for assignment expressions,
2182 shift, member function calls, etc.
2185 Name(strong_eval_order) Type(int)
2188 Enum(strong_eval_order) String(none) Value(0)
2191 Enum(strong_eval_order) String(some) Value(1)
2194 Enum(strong_eval_order) String(all) Value(2)
2196 ftemplate-backtrace-limit=
2197 C++ ObjC++ Joined RejectNegative UInteger Var(template_backtrace_limit) Init(10)
2198 Set the maximum number of template instantiation notes for a single warning or error.
2201 C++ ObjC++ Joined RejectNegative Undocumented Alias(ftemplate-depth=)
2204 C++ ObjC++ Joined RejectNegative UInteger
2205 -ftemplate-depth=<number> Specify maximum template instantiation depth.
2208 C++ ObjC++ WarnRemoved
2211 C++ ObjC++ Optimization Var(flag_threadsafe_statics) Init(1)
2212 -fno-threadsafe-statics Do not generate thread-safe code for initializing local statics.
2215 C ObjC C++ ObjC++ Var(flag_signed_bitfields, 0)
2216 When \"signed\" or \"unsigned\" is not given make the bitfield unsigned.
2219 C ObjC C++ ObjC++ LTO Var(flag_signed_char, 0)
2220 Make \"char\" unsigned by default.
2223 C++ ObjC++ Var(flag_use_cxa_atexit) Init(DEFAULT_USE_CXA_ATEXIT)
2224 Use __cxa_atexit to register destructors.
2226 fuse-cxa-get-exception-ptr
2227 C++ ObjC++ Var(flag_use_cxa_get_exception_ptr) Init(2)
2228 Use __cxa_get_exception_ptr in exception handling.
2230 fvisibility-inlines-hidden
2232 Marks all inlined functions and methods as having hidden visibility.
2234 fvisibility-ms-compat
2235 C++ ObjC++ Var(flag_visibility_ms_compat)
2236 Changes visibility to match Microsoft Visual Studio by default.
2239 C++ ObjC++ WarnRemoved
2240 No longer supported.
2243 C++ ObjC++ WarnRemoved
2244 No longer supported.
2247 C++ ObjC++ Var(flag_weak) Init(1)
2248 Emit common-like symbols as weak symbols.
2251 C ObjC C++ ObjC++ Joined RejectNegative
2252 -fwide-exec-charset=<cset> Convert all wide strings and character constants to character set <cset>.
2255 C ObjC C++ ObjC++ Var(flag_working_directory) Init(-1)
2256 Generate a #line directive pointing at the current working directory.
2259 C++ ObjC++ WarnRemoved
2260 No longer supported.
2263 ObjC ObjC++ Var(flag_zero_link)
2264 Generate lazy class lookup (via objc_getClass()) for use in Zero-Link mode.
2267 ObjC ObjC++ Driver Var(flag_gen_declaration) RejectNegative
2268 Dump declarations to a .decl file.
2270 femit-struct-debug-baseonly
2272 -femit-struct-debug-baseonly Aggressive reduced debug info for structs.
2274 femit-struct-debug-reduced
2276 -femit-struct-debug-reduced Conservative reduced debug info for structs.
2278 femit-struct-debug-detailed=
2279 C ObjC C++ ObjC++ Joined
2280 -femit-struct-debug-detailed=<spec-list> Detailed reduced debug info for structs.
2282 fext-numeric-literals
2283 C++ ObjC++ Var(flag_ext_numeric_literals) Init(1)
2284 Interpret imaginary, fixed-point, or other gnu number suffix as the corresponding
2285 number literal rather than a user-defined number literal.
2288 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2289 -idirafter <dir> Add <dir> to the end of the system include path.
2292 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing filename after %qs)
2293 -imacros <file> Accept definition of macros in <file>.
2296 C ObjC C++ ObjC++ Joined Separate
2297 -imultilib <dir> Set <dir> to be the multilib include subdirectory.
2300 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing filename after %qs)
2301 -include <file> Include the contents of <file> before other files.
2304 C ObjC C++ ObjC++ Joined Separate
2305 -iprefix <path> Specify <path> as a prefix for next two options.
2308 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2309 -isysroot <dir> Set <dir> to be the system root directory.
2312 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2313 -isystem <dir> Add <dir> to the start of the system include path.
2316 C ObjC C++ ObjC++ Joined Separate MissingArgError(missing path after %qs)
2317 -iquote <dir> Add <dir> to the end of the quote include path.
2320 C ObjC C++ ObjC++ Joined Separate
2321 -iwithprefix <dir> Add <dir> to the end of the system include path.
2324 C ObjC C++ ObjC++ Joined Separate
2325 -iwithprefixbefore <dir> Add <dir> to the end of the main include path.
2328 C Undocumented RejectDriver
2335 Do not search standard system include directories (those specified with -isystem will still be used).
2339 Do not search standard system include directories for C++.
2342 C ObjC C++ ObjC++ Joined Separate
2343 ; Documented in common.opt
2346 C ObjC C++ ObjC++ Alias(Wpedantic)
2347 ; Documented in common.opt
2349 print-objc-runtime-info
2351 Generate C header of platform-specific features.
2355 Remap file names when including files.
2359 Conform to the ISO 1998 C++ standard revised by the 2003 technical corrigendum.
2362 C++ ObjC++ Alias(std=c++98)
2363 Conform to the ISO 1998 C++ standard revised by the 2003 technical corrigendum.
2367 Conform to the ISO 2011 C++ standard.
2370 C++ ObjC++ Alias(std=c++11) Undocumented
2371 Deprecated in favor of -std=c++11.
2374 C++ ObjC++ Alias(std=c++14) Undocumented
2375 Deprecated in favor of -std=c++14.
2379 Conform to the ISO 2014 C++ standard.
2382 C++ ObjC++ Alias(std=c++17) Undocumented
2383 Deprecated in favor of -std=c++17.
2387 Conform to the ISO 2017 C++ standard.
2390 C++ ObjC++ Alias(std=c++20) Undocumented
2391 Conform to the ISO 2020 C++ standard (experimental and incomplete support).
2395 Conform to the ISO 2020 C++ standard (experimental and incomplete support).
2398 C++ ObjC++ Alias(std=c++23)
2399 Conform to the ISO 2023 C++ draft standard (experimental and incomplete support).
2402 C++ ObjC++ Undocumented
2403 Conform to the ISO 2023 C++ draft standard (experimental and incomplete support).
2407 Conform to the ISO 2011 C standard.
2410 C ObjC Alias(std=c11)
2411 Deprecated in favor of -std=c11.
2415 Conform to the ISO 2017 C standard (published in 2018).
2418 C ObjC Alias(std=c17)
2419 Conform to the ISO 2017 C standard (published in 2018).
2423 Conform to the ISO 202X C standard draft (experimental and incomplete support).
2426 C ObjC Alias(std=c90)
2427 Conform to the ISO 1990 C standard.
2431 Conform to the ISO 1990 C standard.
2435 Conform to the ISO 1999 C standard.
2438 C ObjC Alias(std=c99)
2439 Deprecated in favor of -std=c99.
2443 Conform to the ISO 1998 C++ standard revised by the 2003 technical
2444 corrigendum with GNU extensions.
2447 C++ ObjC++ Alias(std=gnu++98)
2448 Conform to the ISO 1998 C++ standard revised by the 2003 technical
2449 corrigendum with GNU extensions.
2453 Conform to the ISO 2011 C++ standard with GNU extensions.
2456 C++ ObjC++ Alias(std=gnu++11) Undocumented
2457 Deprecated in favor of -std=gnu++11.
2460 C++ ObjC++ Alias(std=gnu++14) Undocumented
2461 Deprecated in favor of -std=gnu++14.
2465 Conform to the ISO 2014 C++ standard with GNU extensions.
2468 C++ ObjC++ Alias(std=gnu++17) Undocumented
2469 Deprecated in favor of -std=gnu++17.
2473 Conform to the ISO 2017 C++ standard with GNU extensions.
2476 C++ ObjC++ Alias(std=gnu++20) Undocumented
2477 Conform to the ISO 2020 C++ standard with GNU extensions (experimental and incomplete support).
2481 Conform to the ISO 2020 C++ standard with GNU extensions (experimental and incomplete support).
2484 C++ ObjC++ Alias(std=gnu++23)
2485 Conform to the ISO 2023 C++ draft standard with GNU extensions (experimental and incomplete support).
2488 C++ ObjC++ Undocumented
2489 Conform to the ISO 2023 C++ draft standard with GNU extensions (experimental and incomplete support).
2493 Conform to the ISO 2011 C standard with GNU extensions.
2496 C ObjC Alias(std=gnu11)
2497 Deprecated in favor of -std=gnu11.
2501 Conform to the ISO 2017 C standard (published in 2018) with GNU extensions.
2504 C ObjC Alias(std=gnu17)
2505 Conform to the ISO 2017 C standard (published in 2018) with GNU extensions.
2509 Conform to the ISO 202X C standard draft with GNU extensions (experimental and incomplete support).
2512 C ObjC Alias(std=gnu90)
2513 Conform to the ISO 1990 C standard with GNU extensions.
2517 Conform to the ISO 1990 C standard with GNU extensions.
2521 Conform to the ISO 1999 C standard with GNU extensions.
2524 C ObjC Alias(std=gnu99)
2525 Deprecated in favor of -std=gnu99.
2528 C ObjC Alias(std=c90)
2529 Conform to the ISO 1990 C standard.
2533 Conform to the ISO 1990 C standard as amended in 1994.
2536 C ObjC Alias(std=c99)
2537 Conform to the ISO 1999 C standard.
2540 C ObjC Alias(std=c99)
2541 Deprecated in favor of -std=iso9899:1999.
2544 C ObjC Alias(std=c11)
2545 Conform to the ISO 2011 C standard.
2548 C ObjC Alias(std=c17)
2549 Conform to the ISO 2017 C standard (published in 2018).
2552 C ObjC Alias(std=c17)
2553 Conform to the ISO 2017 C standard (published in 2018).
2556 Driver C++ ObjC++ Common Condition(ENABLE_STDLIB_OPTION) Var(flag_stdlib_kind) Joined Enum(stdlib_kind) RejectNegative Init(1)
2557 -stdlib=[libstdc++|libc++] The standard library to be used for C++ headers
2561 Name(stdlib_kind) Type(int)
2564 Enum(stdlib_kind) String(libstdc++) Value(1)
2567 Enum(stdlib_kind) String(libc++) Value(2)
2574 Enable traditional preprocessing.
2578 -trigraphs Support ISO C trigraphs.
2581 C ObjC C++ ObjC++ Var(flag_undef)
2582 Do not predefine system-specific and GCC-specific macros.
2586 ; Documented in common.opt
2590 ; Documented in common.opt
2592 ; This comment is to ensure we retain the blank line above.