如何打开(字面上)GCC的所有警告

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  • 你会认为-Wall也许能行,但不行!仍需-Wextra
  • 你会认为-Wextra也许能行,但不行!我仍然不知道这份名单是否全面。

我如何告诉GCC启用(如果不是,和‘s,或者是!)它发出的警告?

提问于
用户回答回答于

GCC4.4.0的手册只对该版本全面,但它列出了4.4.0的所有可能的警告。它们并不都在链接到的页面上,例如,一些特定于语言的选项出现在C++选项或Obj-C选项的页面上。

包括-Wdouble-promotion,它仅适用于32位单精度浮点单元的cpu,该单元实现了float在硬件上,但是仿真double在软件里。计算为double会使用软件仿真,并且速度更慢。这与一些嵌入式CPU相关,但对于支持64位浮点的现代桌面CPU则完全不相关。

另一个通常并不有用的警告是-Wtraditional,它警告说,在传统的C语言中,格式完全正确的代码具有不同的含义(或不起作用)。"string " "concatenation",或ISO C函数定义!

对于DevSolar抱怨makefile需要根据编译器版本使用不同的警告,如果-Wall -Wextra不合适,那么就不难使用特定于编译器和版本的CFLAGS:

compiler_name := $(notdir $(CC))
ifeq ($(compiler_name),gcc)
compiler_version := $(basename $(shell $(CC) -dumpversion))
endif
ifeq ($(compile_name),clang)
compiler_version := $(shell $(CC) --version | awk 'NR==1{print $$3}')
endif
# ...
wflags.gcc.base := -Wall -Wextra
wflags.gcc.4.7 := -Wzero-as-null-pointer-constant
wflags.gcc.4.8 := $(wflags.gcc.4.7)
wflags.clang.base := -Wall -Wextra
wflags.clang.3.2 := -Weverything
CFLAGS += $(wflags.$(compiler_name).base) $(wflags.$(compiler_name).$(compiler_version))
用户回答回答于

命令:

gcc -Q --help=warning

提供所有受支持的警告选项的列表,并提供有关这些选项是否活动的信息。

-Wall-Wextra

gcc -Wall -Wextra -Q --help=warning

要启用所有警告,可以使用一些regex提取命令行参数。

gcc -Q --help=warning | sed -e 's/^\s*\(\-\S*\)\s*\[\w*\]/\1 /gp;d' | tr -d '\n'

对于我目前的gcc,这提供了:

-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-subscripts -Wcharacter-truncation -Wchkp -Wclobbered -Wcomment -Wcompare-reals -Wconditionally-supported -Wconversion -Wconversion-extra -Wconversion-null -Wcoverage-mismatch -Wcpp -Wctor-dtor-privacy -Wdate-time -Wdeclaration-after-statement -Wdelete-incomplete -Wdelete-non-virtual-dtor -Wdeprecated -Wdeprecated-declarations -Wdesignated-init -Wdisabled-optimization -Wdiscarded-array-qualifiers -Wdiscarded-qualifiers -Wdiv-by-zero -Wdouble-promotion -Weffc++ -Wempty-body -Wendif-labels -Wenum-compare -Wextra -Wfloat-equal -Wformat-contains-nul -Wformat-extra-args -Wformat-nonliteral -Wformat-security -Wformat-signedness -Wformat-y2k -Wformat-zero-length -Wfree-nonheap-object -Wfunction-elimination -Wignored-qualifiers -Wimplicit -Wimplicit-function-declaration -Wimplicit-int -Wimplicit-interface -Wimplicit-procedure -Wincompatible-pointer-types -Winherited-variadic-ctor -Winit-self -Winline -Wint-conversion -Wint-to-pointer-cast -Wintrinsic-shadow -Wintrinsics-std -Winvalid-memory-model -Winvalid-offsetof -Winvalid-pch -Wjump-misses-init -Wline-truncation -Wliteral-suffix -Wlogical-not-parentheses -Wlogical-op -Wlong-long -Wmain -Wmaybe-uninitialized -Wmemset-transposed-args -Wmissing-braces -Wmissing-declarations -Wmissing-field-initializers -Wmissing-include-dirs -Wmissing-parameter-type -Wmissing-prototypes -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-strings -Woverloaded-virtual -Woverride-init -Wpacked -Wpacked-bitfield-compat -Wpadded -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-count-negative -Wshift-count-overflow -Wsign-compare -Wsign-promo -Wsized-deallocation -Wsizeof-array-argument -Wsizeof-pointer-memaccess -Wstack-protector -Wstrict-null-sentinel -Wstrict-prototypes -Wstrict-selector-match -Wsuggest-attribute=const -Wsuggest-attribute=format -Wsuggest-attribute=noreturn -Wsuggest-attribute=pure -Wsuggest-final-methods -Wsuggest-final-types -Wsuggest-override -Wsurprising -Wswitch -Wswitch-bool -Wswitch-default -Wswitch-enum -Wsync-nand -Wsynth -Wsystem-headers -Wtabs -Wtarget-lifetime -Wtraditional -Wtraditional-conversion -Wtrampolines -Wtrigraphs -Wtype-limits -Wundeclared-selector -Wundef -Wunderflow -Wuninitialized -Wunknown-pragmas -Wunsafe-loop-optimizations -Wunsuffixed-float-constants -Wunused -Wunused-but-set-parameter -Wunused-but-set-variable -Wunused-dummy-argument -Wunused-function -Wunused-label -Wunused-local-typedefs -Wunused-macros -Wunused-parameter -Wunused-result -Wunused-value -Wunused-variable -Wuse-without-only -Wuseless-cast -Wvarargs -Wvariadic-macros -Wvector-operation-performance -Wvirtual-move-assign -Wvla -Wvolatile-register-var -Wwrite-strings -Wzero-as-null-pointer-constant -Wzerotrip -frequire-return-statement

现在可以使用它来调用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,这会导致警告,因为某些警告选项只适用于某些语言(例如,C++)。可以通过使用更多的正则表达式来避免这些问题,只包括当前语言所允许的选项。

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