RFR: 8338236: compile error in cgroup code on Linux when using clang

[Matthias Baesken]

On Tue, 13 Aug 2024 07:59:11 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> When building with
> Ubuntu clang version 14.0.0-1ubuntu1.1
> 
> we run into the following compile error (seen on Linux ppc64le, probably also an error on x86_64) :
> 
> /jdk/src/hotspot/os/linux/cgroupV1Subsystem_linux.hpp:65:10: error: 'is_read_only' overrides a member function but is not marked 'override' [-Werror,-Winconsistent-missing-override]
>     bool is_read_only() { return _read_only; }
>          ^
> /jdk/src/hotspot/os/linux/cgroupSubsystem_linux.hpp:108:18: note: overridden virtual function is here
>     virtual bool is_read_only() = 0;
>                  ^
> In file included from /jdk/src/hotspot/os/linux/cgroupSubsystem_linux.cpp:30:
> /jdk/src/hotspot/os/linux/cgroupV2Subsystem_linux.hpp:131:54: error: 'memory_controller' overrides a member function but is not marked 'override' [-Werror,-Winconsistent-missing-override]
>     CachingCgroupController<CgroupMemoryController>* memory_controller() { return _memory; }
>                                                      ^
> /jdk/src/hotspot/os/linux/cgroupSubsystem_linux.hpp:235:62: note: overridden virtual function is here
>     virtual CachingCgroupController<CgroupMemoryController>* memory_controller() = 0;

Seems there is a flag
'-Wsuggest-override'
Warn about overriding virtual functions that are not marked with the override keyword.
https://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Dialect-Options.html#index-Wsuggest-override
in gcc that looks at least similar; we could look into this.

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PR Comment: https://git.openjdk.org/jdk/pull/20562#issuecomment-2286365723