Leif, I also noticed we would need this flag for clang/Xcode too. ~/work/Compiler>clang -S void.c ~/work/Compiler>clang -S void.c -Wpointer-arith void.c:4:14: warning: arithmetic on a pointer to void is a GNU extension [-Wpointer-arith] return Arg + 1; ~~~ ^ 1 warning generated. ~/work/Compiler>cat void.c void * Test (void *Arg) { return Arg + 1; } Thanks, Andrew Fish > On Jul 22, 2020, at 11:05 AM, Leif Lindholm wrote: > > Hi Bob, > > This patch also breaks about half of the ARM/AARCH64 platforms in > edk2-platforms. I agree it should go in at a later stage, but for now, > can we please revert it? > > Regards, > > Leif > > On Mon, Jul 20, 2020 at 04:10:27 +0000, Bob Feng wrote: >> Reviewed-by: Bob Feng >> >> >> -----Original Message----- >> From: PierreGondois >> Sent: Tuesday, July 7, 2020 4:35 PM >> To: devel@edk2.groups.io >> Cc: Pierre Gondois ; Feng, Bob C ; Gao, Liming ; tomas.pilar@arm.com; nd@arm.com >> Subject: [PATCH V2 1/2] BaseTools: Add gcc flag to warn on void* pointer arithmetic >> >> From: Pierre Gondois >> >> By default, gcc allows void* pointer arithmetic. >> This is a GCC extension. >> However: >> - the C reference manual states that void* >> pointer "cannot be operands of addition >> or subtraction operators". Cf s5.3.1 >> "Generic Pointers"; >> - Visual studio compiler treat such operation as >> an error. >> >> To prevent such pointer arithmetic, the "-Wpointer-arith" >> flag should be set for all GCC versions. >> >> The "-Wpointer-arith" allows to: >> "Warn about anything that depends on the "size of" >> a function type or of void. GNU C assigns these >> types a size of 1, for convenience in calculations >> with void * pointers and pointers to functions." >> >> This flag is available since GCC2.95.3 which came out in 2001. >> >> Signed-off-by: Pierre Gondois >> --- >> >> The changes can be seen at: https://github.com/PierreARM/edk2/commits/831_Add_gcc_flag_warning_v2 >> >> Notes: >> v1: >> - Add "-Wpointer-arith" gcc flag. [Pierre] >> v2: >> - Only add the flag for ARM and AARCH64. [Tomas] >> >> BaseTools/Conf/tools_def.template | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) >> >> diff --git a/BaseTools/Conf/tools_def.template b/BaseTools/Conf/tools_def.template >> index 8aeb8a2a6417e41c5660cda5066f52adc8cc3089..397b011ba38f97f81f314f8641ac8bb95d5a2197 100755 >> --- a/BaseTools/Conf/tools_def.template >> +++ b/BaseTools/Conf/tools_def.template >> @@ -1,7 +1,7 @@ >> # >> # Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.
# Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.
-# Portions copyright (c) 2011 - 2019, ARM Ltd. All rights reserved.
>> +# Portions copyright (c) 2011 - 2020, ARM Ltd. All rights >> +reserved.
>> # Copyright (c) 2015, Hewlett-Packard Development Company, L.P.
# (C) Copyright 2020, Hewlett Packard Enterprise Development LP
# Copyright (c) Microsoft Corporation >> @@ -1921,9 +1921,9 @@ NOOPT_*_*_OBJCOPY_ADDDEBUGFLAG = --add-gnu-debuglink=$(DEBUG_DIR)/$(MODULE_N >> DEFINE GCC_ALL_CC_FLAGS = -g -Os -fshort-wchar -fno-builtin -fno-strict-aliasing -Wall -Werror -Wno-array-bounds -include AutoGen.h -fno-common >> DEFINE GCC_IA32_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -m32 -malign-double -freorder-blocks -freorder-blocks-and-partition -O2 -mno-stack-arg-probe >> DEFINE GCC_X64_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -mno-red-zone -Wno-address -mno-stack-arg-probe >> -DEFINE GCC_ARM_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -mlittle-endian -mabi=aapcs -fno-short-enums -funsigned-char -ffunction-sections -fdata-sections -fomit-frame-pointer -Wno-address -mthumb -mfloat-abi=soft -fno-pic -fno-pie >> +DEFINE GCC_ARM_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -Wpointer-arith -mlittle-endian -mabi=aapcs -fno-short-enums -funsigned-char -ffunction-sections -fdata-sections -fomit-frame-pointer -Wno-address -mthumb -mfloat-abi=soft -fno-pic -fno-pie >> DEFINE GCC_ARM_CC_XIPFLAGS = -mno-unaligned-access >> -DEFINE GCC_AARCH64_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -mlittle-endian -fno-short-enums -fverbose-asm -funsigned-char -ffunction-sections -fdata-sections -Wno-address -fno-asynchronous-unwind-tables -fno-unwind-tables -fno-pic -fno-pie -ffixed-x18 >> +DEFINE GCC_AARCH64_CC_FLAGS = DEF(GCC_ALL_CC_FLAGS) -Wpointer-arith -mlittle-endian -fno-short-enums -fverbose-asm -funsigned-char -ffunction-sections -fdata-sections -Wno-address -fno-asynchronous-unwind-tables -fno-unwind-tables -fno-pic -fno-pie -ffixed-x18 >> DEFINE GCC_AARCH64_CC_XIPFLAGS = -mstrict-align -mgeneral-regs-only >> DEFINE GCC_DLINK_FLAGS_COMMON = -nostdlib --pie >> DEFINE GCC_DLINK2_FLAGS_COMMON = -Wl,--script=$(EDK_TOOLS_PATH)/Scripts/GccBase.lds >> -- >> 'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)' >> >> >> >> > >