Re: Build failure "/mnt/data/home/software/openjdk/src/hotspot/share/gc/parallel/objectStartArray.cpp:106:56: error: ‘void* memset(void*, int, size_t)’ writing to an object of type ‘class HeapWord’ with ‘private’ member ‘HeapWord::i’ [-Werror=class-memacc

Karl-Philipp Richter krichter at
Mon Dec 31 22:15:59 UTC 2018

Hi Andrew,
Thanks for your quick reply.

Am 31.12.18 um 21:08 schrieb Andrew Luo:
> Can you run gcc --version and tell us the version of GCC that you are using?
My version is gcc (Ubuntu 8.2.0-7ubuntu1) 8.2.0.

> I'm guessing this was added in a newer version of GCC (class-memaccess was added in GCC 8), and can probably be worked around using -Wno-error=class-memaccess.  That's not saying I don't think we should fix this, just suggesting a workaround for now if you want to compile on GCC 8 before this is fixed.  Although I believe that per the C++ standard you are allowed to memcpy/memset trivial classes (clang only warns on non-trivial classes: so GCC's warning seems to be a bit too broad.
`env MAKEFLAGS= bash ./configure
--with-extra-cxxflags=-Wno-error=class-memaccess && make` avoid the
build failure, however the build now fails because of

In function ‘ContinueInNewThread0’:
error: cast between incompatible function types from ‘int (*)(void *)’
to ‘void * (*)(void *)’ [-Werror=cast-function-type]
     if (pthread_create(&tid, &attr, (void *(*)(void*))continuation,
(void*)args) == 0) {
cc1: all warnings being treated as errors
make[3]: *** [CoreLibraries.gmk:212:
Fehler 1
make[3]: *** Auf noch nicht beendete Prozesse wird gewartet …
make[2]: *** [make/Main.gmk:215: java.base-libs] Fehler 2

ERROR: Build failed for target 'default (exploded-image)' in
configuration 'linux-x86_64-server-release' (exit code 2)

I agree that the issue should be fixed.

Since Ubuntu is not among the least popular Linux distributions, I
recommend a review of your continuous integration system which might
need to include more systems. The setup on GitLab is an example to
perform these tests easily, but you probably already have already a CI
set up which you can extend.

Since I don't need to build OpenJDK urgently, I'd rather see these build
issues detected and fixed by CI coverage of the build process than
stumbling from one to another - it's probably only these two, but afaik
that's a lot of a widely use operating system.

> Are you interested in contributing a fix to this as well - if not I can work on this later this week as well.
I have not enough knowledge to provide a good fix.

> (By the way, your link requires signing in).
My bad, fixed.


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