[PATCH] kconfig: warn about complex selects

[Vegard Nossum]

Hi,

Given recent discussion about kconfig and the "select" feature, I have made
the following quick & dirty patch to detect what I call "complex selects".

For v2.6.25, I get these warnings:
sound/pci/Kconfig:512:error: found complex select: SND_FM801_TEA575X -> VIDEO_V4L1
drivers/ide/Kconfig:890:error: found complex select: ETRAX_IDE -> BLK_DEV_IDEDMA
drivers/acpi/Kconfig:185:error: found complex select: ACPI_HOTPLUG_CPU -> ACPI_CONTAINER

While for v2.6.26-rc1, I get these:
sound/pci/Kconfig:528:error: found complex select: SND_FM801_TEA575X -> VIDEO_V4L1
drivers/media/video/em28xx/Kconfig:2:error: found complex select: VIDEO_EM28XX -> MEDIA_TUNER
drivers/media/video/bt8xx/Kconfig:2:error: found complex select: VIDEO_BT848 -> MEDIA_TUNER
drivers/media/video/saa7134/Kconfig:2:error: found complex select: VIDEO_SAA7134 -> MEDIA_TUNER
drivers/media/video/cx88/Kconfig:2:error: found complex select: VIDEO_CX88 -> MEDIA_TUNER
drivers/media/video/cx23885/Kconfig:2:error: found complex select: VIDEO_CX23885 -> MEDIA_TUNER
drivers/media/video/ivtv/Kconfig:2:error: found complex select: VIDEO_IVTV -> MEDIA_TUNER
drivers/media/video/cx18/Kconfig:2:error: found complex select: VIDEO_CX18 -> MEDIA_TUNER
drivers/media/video/pvrusb2/Kconfig:2:error: found complex select: VIDEO_PVRUSB2 -> MEDIA_TUNER
drivers/media/video/Kconfig:690:error: found complex select: VIDEO_MXB -> MEDIA_TUNER
drivers/media/video/usbvision/Kconfig:2:error: found complex select: VIDEO_USBVISION -> MEDIA_TUNER
drivers/acpi/Kconfig:188:error: found complex select: ACPI_HOTPLUG_CPU -> ACPI_CONTAINER

(In other words, the number of these has increased significantly since the
last release, and these will probably be hit as compile errors at one point
or another.)

I am not a kconfig expert, so I might have missed some things. Roman, is this
even remotely good? I think it's probably a good start anyway.

One other idea that might be feasible in terms of both correctness and
usability: If a symbol foo does "select bar", maybe foo should simply inherit
bar's dependencies? This allows foo to be visible in most cases (when the
dependencies of foo and bar are both satisified), but won't brute-force-enable
any symbols.

Either way, here's my contribution to the discussion.


Vegard