freebsd stable - Aug 2016 - stable/11 -r304029: amd64-gcc says: sys/dev/hptmv/vdevice.h error: variably modified '_ArrayTables' at file scope

[This was part of Bugzilla report 211540 against the HighPoint RocketRAID 182x
driver code. My -r304029 build attempt using -r304029 still reports the error.
This note is just about a build-ability problem under amd64-gcc: I only tried it
to add to the testing of 11.0. I'm personally not blocked by the problem.]

Attempting to build stable/11 -r304029 for TARGET_ARCH=amd64 with amd64-gcc
(amd64-xtoolchain-gcc) reports:

/usr/src/sys/dev/hptmv/vdevice.h:145:2: error: variably modified
'_ArrayTables' at file scope [-Werror]
  BYTE    _ArrayTables[MAX_ARRAY_PER_VBUS * ARRAY_VDEV_SIZE];
  ^

The "variably modified '_ArrayTables' at file scope" messages
refer to (various .h files contributing):

#define MAX_VDEVICE_PER_VBUS 8
. . .
#ifndef MAX_ARRAY_PER_VBUS
#define MAX_ARRAY_PER_VBUS (MAX_VDEVICE_PER_VBUS*2) /* worst case */
#endif
. . .
#define ARRAY_VDEV_SIZE
((UINT)(ULONG_PTR)&((PVDevice)0)->u+sizeof(RaidArray))
. . .
typedef struct _VBus  {
. . .
#ifdef SUPPORT_ARRAY
        PVDevice pFreeArrayLink;
        BYTE    _ArrayTables[MAX_ARRAY_PER_VBUS * ARRAY_VDEV_SIZE];
#endif
. . .
} VBus;


ARRAY_VDEV_SIZE from /usr/src/sys/dev/hptmv/vdevice.h is what is being
complained about for its use in typedef struct _VBus's _ArrayTables field at
file scope.


amd64-gcc does not treat
((UINT)(ULONG_PTR)&((PVDevice)0)->u+sizeof(RaidArray)) as a known
constant where such is required in the _ArrayTables field declaration.



/usr/src/sys/dev/hptmv/vdevice.h having
((UINT)(ULONG_PTR)&((PVDevice)0)->u+sizeof(RaidArray)) for
ARRAY_VDEV_SIZE goes back to -r136849 and the file's creation on
2004-Oct-24. It appears that SUPPORT_ARRAY was defined back then. SO the code is
old.



Context details:

# svnlite info /usr/src/ | grep "Rev[i:]" 
you have mail
Revision: 304029
Last Changed Rev: 304029

# uname -apKU
FreeBSD FreeBSDx64 11.0-PRERELEASE FreeBSD 11.0-PRERELEASE #4 r304029M: Sat Aug
13 00:40:30 PDT 2016     markmi at
FreeBSDx64:/usr/obj/clang/amd64.amd64/usr/src/sys/GENERIC-NODBG  amd64 amd64
1100500 1100500

# more ~/src.configs/src.conf.amd64-xtoolchain.amd64-host 
TO_TYPE=amd64
TOOLS_TO_TYPE=x86_64
VERSION_CONTEXT=11.0
#
KERNCONF=GENERIC-NODBG
TARGET=${TO_TYPE}
.if ${.MAKE.LEVEL} == 0
TARGET_ARCH=${TO_TYPE}
.export TARGET_ARCH
.endif
#
WITHOUT_CROSS_COMPILERWITHOUT_SYSTEM_COMPILER#
WITH_LIBCPLUSPLUSWITHOUT_BINUTILS_BOOTSTRAPWITHOUT_CLANG_BOOTSTRAPWITH_CLANGWITH_CLANG_IS_CCWITH_CLANG_FULLWITH_CLANG_EXTRASWITH_LLDB#PORTS_MODULES=emulators/virtualbox-ose-additions
#
#WITH_BOOT= for amd64-xtoolschain-gcc/amd64-gcc gets something like... 
# --- all_subdir_sys ---
# -994 bytes available
# *** [boot2] Error code 1
WITHOUT_BOOTWITH_LIB32#
WITHOUT_ELFTOOLCHAIN_BOOTSTRAPWITHOUT_GCC_BOOTSTRAPWITHOUT_GCCWITHOUT_GCC_IS_CCWITHOUT_GNUCXX#
NO_WERROR#WERRORMALLOC_PRODUCTION#
WITH_DEBUG_FILES#
#
# For TO (so-called "cross") stages . . .
# So-called-cross via ${TO_TYPE}-xtoolchain-gcc/${TO_TYPE}-gcc. . .
# TOOLS_TO_TYPE based on ${TO_TYPE}-xtoolchain-gcc related binutils. . .
#
CROSS_TOOLCHAIN=${TO_TYPE}-gcc
X_COMPILER_TYPE=gcc
CROSS_BINUTILS_PREFIX=/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/
.if ${.MAKE.LEVEL} == 0
XCC=/usr/local/bin/${TOOLS_TO_TYPE}-portbld-freebsd${VERSION_CONTEXT}-gcc
XCXX=/usr/local/bin/${TOOLS_TO_TYPE}-portbld-freebsd${VERSION_CONTEXT}-g++
XCPP=/usr/local/bin/${TOOLS_TO_TYPE}-portbld-freebsd${VERSION_CONTEXT}-cpp
.export XCC
.export XCXX
.export XCPP
XAS=/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/as
XAR=/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ar
XLD=/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ld
XNM=/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/nm
XOBJCOPY=/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/objcopy
XOBJDUMP=/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/objdump
XRANLIB=/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/ranlib
XSIZE=/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/size
#NO-SUCH: XSTRINGS=/usr/local/${TOOLS_TO_TYPE}-freebsd/bin/strings
XSTRINGS=/usr/local/bin/${TOOLS_TO_TYPE}-freebsd-strings
.export XAS
.export XAR
.export XLD
.export XNM
.export XOBJCOPY
.export XOBJDUMP
.export XRANLIB
.export XSIZE
.export XSTRINGS
.endif
#
#
# From based on clang (via system). . .
#
.if ${.MAKE.LEVEL} == 0
CC=/usr/bin/clang
CXX=/usr/bin/clang++
CPP=/usr/bin/clang-cpp
.export CC
.export CXX
.export CPP
.endif

# more ~/src.configs/make.conf 
CFLAGS.gcc+= -v

==Mark Millard
markmi at dsl-only.net