man gcc

Warning Options
-fsyntax-only -fmax-errors=n -Wpedantic -pedantic-errors -w -Wextra -Wall -Waddress -Waggregate-return
-Waggressive-loop-optimizations -Warray-bounds -Warray-bounds=n -Wbool-compare -Wno-attributes -Wno-builtin-macro-redefined
-Wc90-c99-compat -Wc99-c11-compat -Wc++-compat -Wc++11-compat -Wc++14-compat -Wcast-align -Wcast-qual -Wchar-subscripts -Wclobbered
-Wcomment -Wconditionally-supported -Wconversion -Wcoverage-mismatch -Wdate-time -Wdelete-incomplete -Wno-cpp -Wno-deprecated
-Wno-deprecated-declarations -Wno-designated-init -Wdisabled-optimization -Wno-discarded-qualifiers -Wno-discarded-array-qualifiers
-Wno-div-by-zero -Wdouble-promotion -Wempty-body -Wenum-compare -Wno-endif-labels -Werror -Werror=* -Wfatal-errors -Wfloat-equal
-Wformat -Wformat=2 -Wno-format-contains-nul -Wno-format-extra-args -Wformat-nonliteral -Wformat-security -Wformat-signedness
-Wformat-y2k -Wframe-larger-than=len -Wno-free-nonheap-object -Wjump-misses-init -Wignored-qualifiers -Wincompatible-pointer-types
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int -Winit-self -Winline -Wno-int-conversion -Wno-int-to-pointer-cast
-Wno-invalid-offsetof -Winvalid-pch -Wlarger-than=len -Wunsafe-loop-optimizations -Wlogical-op -Wlogical-not-parentheses -Wlong-long
-Wmain -Wmaybe-uninitialized -Wmemset-transposed-args -Wmissing-braces -Wmissing-field-initializers -Wmissing-include-dirs
-Wno-multichar -Wnonnull -Wnormalized=[none|id|nfc|nfkc]
-Wodr -Wno-overflow -Wopenmp-simd -Woverlength-strings -Wpacked -Wpacked-bitfield-compat -Wpadded -Wparentheses
-Wpedantic-ms-format -Wno-pedantic-ms-format -Wpointer-arith -Wno-pointer-to-int-cast -Wredundant-decls -Wno-return-local-addr
-Wreturn-type -Wsequence-point -Wshadow -Wno-shadow-ivar -Wshift-count-negative -Wshift-count-overflow -Wsign-compare
-Wsign-conversion -Wfloat-conversion -Wsizeof-pointer-memaccess -Wsizeof-array-argument -Wstack-protector -Wstack-usage=len
-Wstrict-aliasing -Wstrict-aliasing=n -Wstrict-overflow -Wstrict-overflow=n -Wsuggest-attribute=[pure|const|noreturn|format]
-Wsuggest-final-types -Wsuggest-final-methods -Wsuggest-override -Wmissing-format-attribute -Wswitch -Wswitch-default -Wswitch-enum
-Wswitch-bool -Wsync-nand -Wsystem-headers -Wtrampolines -Wtrigraphs -Wtype-limits -Wundef -Wuninitialized -Wunknown-pragmas
-Wno-pragmas -Wunsuffixed-float-constants -Wunused -Wunused-function -Wunused-label -Wunused-local-typedefs -Wunused-parameter
-Wno-unused-result -Wunused-value -Wunused-variable -Wunused-but-set-parameter -Wunused-but-set-variable -Wuseless-cast
-Wvariadic-macros -Wvector-operation-performance -Wvla -Wvolatile-register-var -Wwrite-strings -Wzero-as-null-pointer-constant