Incorporation of GCC 6

[korli]

Provisioning ticket for GCC 6 to track activities and see if it works well. Current release is 6.3

[korli]

Should probably include binutils 2.28.

[korli]

Current release is now 6.4

[mt]

Hi, I think we need resolve two bugs to build with gcc6.

• We need to update src/apps/serialconnect/libvterm/src/encoding.c to avoid -Werror=misleading-indentation at line 77-85.

​http://cgit.haiku-os.org/haiku/tree/src/apps/serialconnect/libvterm/src/encoding.c#n77

​https://github.com/neovim/libvterm/commit/224b8dcde1c9640c29a34aa60c0f0d56ad298449

• We need to resolve -Werror=nonnull-compare in src/add-ons/kernel/file_systems/userlandfs/shared/ObjectTracker.cpp at line 80 and 93.

​http://cgit.haiku-os.org/haiku/tree/src/add-ons/kernel/file_systems/userlandfs/shared/ObjectTracker.cpp#n80

​http://cgit.haiku-os.org/haiku/tree/src/add-ons/kernel/file_systems/userlandfs/shared/ObjectTracker.cpp#n93

[korli]

Hi mt, both issues should fixed in hrev51266. Thanks for pointing them!

[mt]

I tested hrev51266, build succeeded with GCC 6.4.But haiku crashes at startup. Adding '-fno-delete-null-pointer-checks' to kernel flags may be workaround for it.

[mt]

hrev51266_gcc6 with VirtualBox 5.1.22

[korli]

Maybe better to try to "fix" the code: it seems KDiskDeviceManager::Default() can be NULL at ​https://github.com/haiku/haiku/blob/master/src/system/kernel/fs/vfs.cpp#L7784 and ​https://github.com/haiku/haiku/blob/master/src/system/kernel/fs/vfs.cpp#L7278

It seems that AutoLocker checks if fLockable isn't NULL... see ​https://github.com/haiku/haiku/blob/master/headers/private/shared/AutoLocker.h#L130

[mt]

Replying to korli:

Maybe better to try to "fix" the code: it seems KDiskDeviceManager::Default() can be NULL

I added null check to vfs.cpp at line 7282 and 7784, then gcc6 build works. But, gcc5 build works without applying patch or kernel flags. So I think gcc6 deletes null pointer check somewhere in kernel.

[korli]

Applied in hrev51274. AutoLocker should probably panic in the kernel when used with a NULL Lockable.

[korli]

Reverted hrev51274 and applied the workaround flag for GCC6 in hrev51277. The problematic code (DiskDeviceManager) isn't easy to fix because it tries to lock the default DDM when initializing the default one too.

[pulkomandy]

@korli: please set the "obsolete" flag on patches when applying them and keeping the ticket open. Otherwise it's hard to track which are still waiting to be merged.

[mt]

It seems null check need to be done before assigning the value [1], so I rewrite vfs.cpp patch. After that hrev51386 gcc6 build boots without '-fno-delete-null-pointer-checks' flag.

[1] ​https://isc.sans.edu/diary/A+new+fascinating+Linux+kernel+vulnerability/6820

[korli]

mt, I'm sorry but adding such checks didn't go through already with hrev51274. Why would it go in this place? The flag '-fno-delete-null-pointer-checks' is already effective anyway.

[mt]

korli, sorry, I had forgotten that hrev51274 works, please ignore my previous comment.

[waddlesplash]

There is another KDL with GCC 7.3, see #14160.

[waddlesplash]

GCC7 is now used by default in hrev51973.