Build portability: enable or disable warnings

[Dr Andrew John Hughes]

On 10:32 Thu 19 May     , Alan Bateman wrote:
> David Holmes wrote:
> > :
> >
> >> In contrast, there are basically two Java compilers in general use 
> >> (javac and ecj)
> >> and one is part of OpenJDK.  Yet, the Java code does not have -Werror 
> >> enabled by default and there
> >> are a mass of warnings there as a result.
> >
> > I don't understand the point you are making here. Does javac even have 
> > a -Werror? The bulk of javac warnings stem from legacy code being 
> > compiled under newer compilers with new language features - the 
> > resulting code is not erroneous hence only a warning is issued.
> >
> > I think comparing C/C++ compiler warnings with javac compiler warnings 
> > is like comparing apples and elephants.
> Yes, javac has -Werror and the build has JAVAC_WARNINGS_FATAL to turn it 
> on. I just checked my recent build of the jdk7/jdk7 forest and javac 
> emits a total of 9 warnings (7 are unsafe usages of varargs methods and 
> the other two are unreachable catch clauses). That isn't a lot but javac 
> doesn't have many warnings enabled by default. A nice project for 
> someone would be to change the build to -Werror by default and gradually 
> crank up the warnings listed by -Xlint.
> 

javac is generally a good citizen.  I was thinking of jdk code.

I have built with JAVAC_MAX_WARNINGS=true on a number of occasions and
it's only recently (thanks to a few fixes from myself) that it's
actually been able to complete the build, due to some Makefiles
turning on Werror separately.  I expect with JAVAC_WARNINGS_FATAL as
well we wouldn't get past CORBA.

I do think having a switch to turn on everything but serial and deprecated 
warnings would be a more achievable goal, and would help get rid of
the remaining 1.5 stuff.

> -Alan.
> 
> 

-- 
Andrew :)

Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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