如何打开（字面上）所有GCC警告？

Question

我真的要启用GCC的所有警告。（您会认为这很容易...）

• 您-Wall可能认为可以解决问题，但不能！还需要-Wextra。

• 您-Wextra可能认为可以解决问题，但不能！并非所有此处列出的警告（例如-Wshadow）都已启用。而且我仍然不知道这个清单是否全面。

我如何告诉GCC启用（如果不是，则不是，否则为！）所有警告？

Answer 1

我同意先前的回答，即从字面上启用所有警告可能无益，但是GCC确实提供了一种实现此目的的合理方便的方法。命令gcc -Q --help=warning提供所有受支持的警告选项的列表，以及有关它们是否处于活动状态的信息。这可以通过方式来找出哪个选项（不）例如通过启用-Wall和-Wextragcc -Wall -Wextra -Q --help=warning要启用所有警告，您可以使用一些正则表达式提取命令行参数gcc -Q --help=warning | sed -e 's/^\s*\(\-\S*\)\s*\[\w*\]/\1 /gp;d' | tr -d '\n'对于我当前的GCC，这给出了：-Wabi -Wabi-tag -Waddress -Waggregate-return -Waggressive-loop-optimizations -Waliasing -Walign-commons -Wampersand -Warray-bounds -Warray-temporaries -Wassign-intercept -Wattributes -Wbad-function-cast -Wbool-compare -Wbuiltin-macro-redefined -Wc ++-compat -Wc ++ 0x-compat -Wc ++ 14-compat -Wc-binding-type -Wc90-c99-compat -Wc99-c11-compat -Wcast-align -Wcast-qual -Wchar下标-W字符截断-Wchkp -Wclobbered -Wcomment -Wcompare-reals -W有条件支持-Wconversion -Wconversion-extra -Wconversion-null -Wcoverage-mismatch -Wcpp -Wctor-dtor-privacy -Wdate-time -Wdeclaration -声明后-Wdelete不完整-Wdelete-non-virtual-dtor -Wdeprecated -Wdeprecated-clarifications -Wdesignated-init -Wdisabled-optimization -Wdiscarded-array-qualifiers -Wdiscarded-qualifiers -Wdiv-by-零-Wdouble-promotion -Weffc ++-虚空的身体-Wendif标签-Wenum-compare -Wextra -Wfloat-equal -Wformat-contains-nul -Wformat-extra-args -Wformat-nonliteral -Wformat-security -Wformat-signness -Wformat-y2k -Wformat-zero-length -Wfree -非堆对象-Wfunction消除-Wignored限定词-Wimplicit -Wimplicit函数声明-Wimplicit-int -Wimplicit接口-Wimplicit-procedure -Wincompatible-pointer类型-Winherited-variadic-ctor -Winit-self -Winline -Wint转换-Wint-pointer-cast -Wintrinsic-shadow -Wintrinsics-std -Winvalid-memory-model -Winvalid-offsetof -Winvalid-pch -Wjump-misses-init -Wline-truncation -Wliteral后缀-Wologic -非括号-Wologic-op -Wlong-long -Wmain -Wmay尚未初始化-Wmemset转换后的参数-Wmissing括号-Wmissing-声明-Wmissing-field-initializers -Wmissing-include-dirs -Wmissing-parameter-type -遗忘原型-Wmultichar -Wnarrowing -Wnested-externs -Wnoexcept -Wnon-template-friend -Wnon-virtual-dtor -Wnonnull -Wodr -Wold-style-cast -Wold-style-declaration -Wold-style-definition -Wopenmp-simd -Woverflow -Woverlength字符串-Woverloaded-virtual -Woverride-init -Wpacked -Wpacked-bitfield-compat -Wpapped -Wparentheses -Wpedantic -Wpmf-conversions -Wpointer-arith -Wpointer-sign -Wpointer-to-int-cast -Wpragmas -Wproperty -assign-default -Wprotocol -Wreal-q-constant -Wrealloc-lhs -Wrealloc-lhs-all -Wredundant-decls -Wreorder -Wreturn-local-addr -Wreturn-type -Wselector -Wsequence-point -Wshadow -Wshadow-ivar -Wshift计数负数-Wshift计数溢出-Wsign比较-Wsign促销-Wsize释放-Wsizeof数组参数-Wsizeof-pointer-memaccess -Wstack-protector -Wstrict-null-Sentinel -Wstrict-prototypes -严格选择匹配-Wsuggest-属性=常量-Wsuggest-属性=格式-Wsuggest-属性=不返回-Wsuggest-属性=纯-Wsuggest-最终方法-Wsuggest-最终类型-Wsuggest-override -Wsurprising -Wswitch -Wswitch-bool -Wswitch -default -Wswitch枚举-Wsync-nand -Wsynth -Wsystem-headers -Wtabs -Wtarget-lifetime -Wtraditional -Wraditional-conversion -Wtrampolines -Wtrigraphs -Wtype-limits -Wondeclared-selector -Wundef -Wunderflow -Wuninitialized -Wunknown-pragmas -Wunsafe循环优化-Wunsuffixed浮点常量-Wunused -Wunused-但是设置参数-Wunused-但设置变量-Wunused-Dummy参数-Wunused函数-Wunused-label -Wunused-local-defs -无用的宏-无用的参数-无用的结果-无用的值-无用的变量-Wuse-without-only-无用的铸造-Wvarargs -Wvariadic-macros -Wvector-operation-performance-Wvirtual-move-assign-Wvla -Wvolatile-register-var -Wwrite-strings -Wzero-null-pointer-constant -Wzerotrip -frequire-return-statement现在可以用来呼叫GCC，即gcc $(gcc -Q --help=warning | sed -e 's/^\s*\(\-\S*\)\s*\[\w*\]/\1 /gp;d' | tr -d '\n')但是请注意，由于某些警告选项仅适用于某些语言（例如C++），因此会产生警告。可以通过使用更多的正则表达式来避免这些问题，以仅包括当前语言允许的选项，或者-Wno-whatever在通话结束时添加适当的选项。

Answer 2

不可能在所有警告都启用的情况下进行编程（除非您要忽略它们，否则为什么要打扰？）。例如，假设您使用以下标志集：-Wstrict-prototypes -Wtraditional。即使启用了两个警告，以下程序也会抱怨。/tmp $ cat main.c int main(int argc, char **argv) {    return 0;}/tmp $ gcc -Wstrict-prototypes -Wtraditional main.c main.c: In function ‘main’:main.c:1:5: warning: traditional C rejects ISO C style function definitions [-Wtraditional] int main(int argc, char **argv) {     ^您可能会认为“好吧，那我将使用旧样式的原型”。不，这行不通。/tmp $ cat main.c int main(argc, argv)    int argc;    char **argv;{    return 0;}/tmp $ gcc -Wstrict-prototypes -Wtraditional main.c main.c:1:5: warning: function declaration isn’t a prototype [-Wstrict-prototypes] int main(argc, argv)     ^不，不指定任何原型也是错误的，因为编译器也会抱怨。/tmp $ cat main.c int main() {    return 0;}/tmp $ gcc -Wstrict-prototypes -Wtraditional main.c main.c:1:5: warning: function declaration isn’t a prototype [-Wstrict-prototypes] int main() {     ^如果在程序中定义任何函数，则不能使用所有标志，因为编译器会抱怨任何可想像的函数定义。对于C ++，这是可能的（该-Wtraditional标志不存在），并且可以编译非常简单的程序。要启用所有警告，请使用以下警告列表（可能有些警告是重复的，因为我没有费心过滤启用的警告-Wall）。-Wabi -Wctor-dtor-privacy -Wnon-virtual-dtor -Wreorder -Weffc++ -Wstrict-null-sentinel -Wno-non-template-friend -Wold-style-cast -Woverloaded-virtual -Wno-pmf-conversions -Wsign-promo -Wextra -Wall -Waddress -Waggregate-return -Warray-bounds -Wno-attributes -Wno-builtin-macro-redefined -Wc++0x-compat -Wcast-align -Wcast-qual -Wchar-subscripts -Wclobbered -Wcomment -Wconversion -Wcoverage-mismatch -Wno-deprecated -Wno-deprecated-declarations -Wdisabled-optimization -Wno-div-by-zero -Wempty-body -Wenum-compare -Wno-endif-labels -Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 -Wno-format-contains-nul -Wno-format-extra-args -Wformat-nonliteral -Wformat-security -Wformat-y2k -Wignored-qualifiers -Winit-self -Winline -Wno-int-to-pointer-cast -Wno-invalid-offsetof -Winvalid-pch -Wunsafe-loop-optimizations -Wlogical-op -Wlong-long -Wmain -Wmissing-braces -Wmissing-field-initializers -Wmissing-format-attribute -Wmissing-include-dirs -Wmissing-noreturn -Wno-mudflap -Wno-multichar -Wnonnull -Wno-overflow -Woverlength-strings -Wpacked -Wpacked-bitfield-compat -Wpadded -Wparentheses -Wpointer-arith -Wredundant-decls -Wreturn-type -Wsequence-point -Wshadow -Wsign-compare -Wsign-conversion -Wstack-protector -Wstrict-aliasing=1 -Wstrict-overflow=5 -Wswitch -Wswitch-default -Wswitch-enum -Wsync-nand -Wsystem-headers -Wtrigraphs -Wtype-limits -Wundef -Wuninitialized -Wunknown-pragmas -Wno-pragmas -Wunreachable-code -Wunused -Wunused-function -Wunused-label -Wunused-parameter -Wunused-value -Wunused-variable -Wvariadic-macros -Wvla -Wvolatile-register-var -Wwrite-strings