Re: [Qemu-devel] [PATCH for-2.12 2/2] make: switch from -I to -iquote

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Mar 21, 2018 at 05:22:07PM +0200, Michael S. Tsirkin wrote:
> Our rule right now is to use <> for external headers,
> "" for internal ones. The idea was to avoid conflicts
> between e.g. a system file named <trace.h> and an
> internal one by the same name.
> 
> Unfortunately we use -I compiler flag so it does not
> help: a system file doing #include <trace.h> will
> still pick up ours first.

Has that actually hit you practice ?  I'm wondering if this
is just theoretical in which case it could wait till 2.13
since this scenario has existed in QEMU along time, or
a real problem right now requiring fix in 2.12.


> To fix, switch to -iquote which is supported by both
> gcc and clang and only affects #include "" directives.

Fine since we don't support anything other than
gcc and clang. I'm assuming -iquote has been supported
by these two compilers for a long time though ? The GCC
docs annoyingly don't ever mention what release features
appear in :-(

> 
> As a side effect, this catches any future uses of
>  #include <> for internal headers.
> 
> Suggested-by: Stefan Weil <sw@weilnetz.de>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


> 
> I still think we want to switch to a more formal rule such as qemu/
> prefix for all includes down the road, but this will at least catch any
> scheme violations from creeping in meanwhile.
> 
> 
>  configure       | 16 ++++++++--------
>  rules.mak       |  2 +-
>  Makefile.target |  4 ++--
>  3 files changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/configure b/configure
> index af72fc8..23a4f3b 100755
> --- a/configure
> +++ b/configure
> @@ -534,7 +534,7 @@ QEMU_CFLAGS="-fno-strict-aliasing -fno-common -fwrapv $QEMU_CFLAGS"
>  QEMU_CFLAGS="-Wall -Wundef -Wwrite-strings -Wmissing-prototypes $QEMU_CFLAGS"
>  QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls $QEMU_CFLAGS"
>  QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $QEMU_CFLAGS"
> -QEMU_INCLUDES="-I. -I\$(SRC_PATH) -I\$(SRC_PATH)/accel/tcg -I\$(SRC_PATH)/include"
> +QEMU_INCLUDES="-iquote . -iquote \$(SRC_PATH) -iquote \$(SRC_PATH)/accel/tcg -iquote \$(SRC_PATH)/include"
>  if test "$debug_info" = "yes"; then
>      CFLAGS="-g $CFLAGS"
>      LDFLAGS="-g $LDFLAGS"
> @@ -6560,19 +6560,19 @@ if test "$vxhs" = "yes" ; then
>  fi
>  
>  if test "$tcg_interpreter" = "yes"; then
> -  QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/tci $QEMU_INCLUDES"
> +  QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/tci $QEMU_INCLUDES"
>  elif test "$ARCH" = "sparc64" ; then
> -  QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/sparc $QEMU_INCLUDES"
> +  QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/sparc $QEMU_INCLUDES"
>  elif test "$ARCH" = "s390x" ; then
> -  QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/s390 $QEMU_INCLUDES"
> +  QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/s390 $QEMU_INCLUDES"
>  elif test "$ARCH" = "x86_64" -o "$ARCH" = "x32" ; then
> -  QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/i386 $QEMU_INCLUDES"
> +  QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/i386 $QEMU_INCLUDES"
>  elif test "$ARCH" = "ppc64" ; then
> -  QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/ppc $QEMU_INCLUDES"
> +  QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/ppc $QEMU_INCLUDES"
>  else
> -  QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/\$(ARCH) $QEMU_INCLUDES"
> +  QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg/\$(ARCH) $QEMU_INCLUDES"
>  fi
> -QEMU_INCLUDES="-I\$(SRC_PATH)/tcg $QEMU_INCLUDES"
> +QEMU_INCLUDES="-iquote \$(SRC_PATH)/tcg $QEMU_INCLUDES"
>  
>  echo "TOOLS=$tools" >> $config_host_mak
>  echo "ROMS=$roms" >> $config_host_mak
> diff --git a/rules.mak b/rules.mak
> index 6e94333..93a0702 100644
> --- a/rules.mak
> +++ b/rules.mak
> @@ -29,7 +29,7 @@ QEMU_DGFLAGS += -MMD -MP -MT $@ -MF $(@D)/$(*F).d
>  # dir, one absolute and the other relative to the compiler working
>  # directory. These are the same for target-independent files, but
>  # different for target-dependent ones.
> -QEMU_LOCAL_INCLUDES = -I$(BUILD_DIR)/$(@D) -I$(@D)
> +QEMU_LOCAL_INCLUDES = -iquote $(BUILD_DIR)/$(@D) -iquote $(@D)
>  
>  WL_U := -Wl,-u,
>  find-symbols = $(if $1, $(sort $(shell $(NM) -P -g $1 | $2)))
> diff --git a/Makefile.target b/Makefile.target
> index 6549481..d0ec77a 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -11,9 +11,9 @@ $(call set-vpath, $(SRC_PATH):$(BUILD_DIR))
>  ifdef CONFIG_LINUX
>  QEMU_CFLAGS += -I../linux-headers
>  endif
> -QEMU_CFLAGS += -I.. -I$(SRC_PATH)/target/$(TARGET_BASE_ARCH) -DNEED_CPU_H
> +QEMU_CFLAGS += -iquote .. -iquote $(SRC_PATH)/target/$(TARGET_BASE_ARCH) -DNEED_CPU_H
>  
> -QEMU_CFLAGS+=-I$(SRC_PATH)/include
> +QEMU_CFLAGS+=-iquote $(SRC_PATH)/include
>  
>  ifdef CONFIG_USER_ONLY
>  # user emulator name
> -- 
> MST
> 

Regards,
Daniel
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