[OpenJDK 2D-Dev] [PATCH] Build fails to compile jchuff.c

[Adam Farley8]

Hi All,

Under these circumstances, jchuff.c will not compile:

Platform: zLinux (s390x)
Release: JDK9 (may affect other JDKs).
GCC Version: 4.8.5
Notes: --disable-warnings-as-errors suppresses this error.

The error is:

/home/adamfarl/hotspot/jdk9/jdk/src/java.desktop/share/native/libjavajpeg/jchuff.c:
In function 'jGenOptTbl':
/home/adamfarl/hotspot/jdk9/jdk/src/java.desktop/share/native/libjavajpeg/jchuff.c:808:18:
error: array subscript is below array bounds [-Werror=array-bounds]
       while (bits[j] == 0)
                  ^

This is a continuation of a conversation in the build-dev mailing list, if 
anyone wants to 
check the history.

The short version is that, while you *can* suppress the problem by adding 
--disable-warnings-as-errors to your configure step, I posit that a 
builder shouldn't 
have to.

Various solutions were debated. One involves changing Awt2dLibraries.gmk.

Basically you change line 494 to this:

    DISABLED_WARNINGS_gcc := clobbered array-bounds, \

I'm running a build now to check that works, but basically we should end 
up with a 
-Wno-array-bounds on the gcc compile command for jchuff.c, thereby 
ignoring the warning.

A smarter variant involves checking for that specific version of the gcc, 
but that seems 
wordy to me for this problem. Keeping it simple. :)

Thoughts?

Best Regards

Adam Farley

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