[MCOMPILER-57] State default source (1.3) and target (1.1) in the documentation

• Type: Improvement
• Status: Closed
• Priority: Trivial
• Resolution: Fixed
• Affects Version/s: 2.0.2
• Fix Version/s: 2.1
• Assignee: Dennis Lundberg
• Reporter: Gisbert Amm
• Created: 16/Aug/07 02:44
• Updated: 08/Apr/15 08:03
• Resolved: 09/Oct/07 16:21

Description

The documentation does currently say nothing about the compiler defaults, especially source and target version, which is 1.3 and 1.1 (byte code 45.3). It would be helpful to add this information to the docs to make the defaults obvious.

Respective mailing list content:

This has been discussed several times on this list.

IMO, the default compilation target being 1.1 (or another hard-defined
version) meets the rule of least surprise. You can argue that you
don't like 1.1 and you'd prefer 1.3 or even 1.5 but that is another
discussion.

In contrast, the rule of most surprise would be "my build changes when
I change my JDK" or "my build changes when I build things on different
machines". This is the absolute worst thing you can run into when
trying to standardize and control your build process.

If you want to target a specific JDK, then simply add the compiler
configuration in your poms. If you feel this has not been documented
sufficiently, then post a RFE in Jira and someone will add some text
to the proper page(s) on the site.

Wayne

On 8/15/07, Gisbert Amm <[e-mail]> wrote:

>> Searching for version issues, I had a closer look at the *.class files
>> generated by Maven2 with the default compiler settings and found that
>> the first bytes of them are "cafe babe 0003 002D ...", which is byte
>> code version 45.3 = Java 1.1.
>>
>> First I was believing that I had this (target 1.1) configured somewhere
>> by accident. However, I didn't find any such configuration, therefore I
>> dug into the plexus-compiler source and found the following in
>> plexus-site/plexus-components/plexus-compiler/plexus-compilers/plexus-compiler-javac/src/main/java/org/codehaus/plexus/compiler/javac/JavacCompiler.java:
>>
>> // TODO: this could be much improved
>> if ( StringUtils.isEmpty( config.getTargetVersion() ) )
>>

{ >> // Required, or it defaults to the target of your JDK (eg 1.5) >> args.add( "-target" ); >> args.add( "1.1" ); >> }

>> else
>>

{ >> args.add( "-target" ); >> args.add( config.getTargetVersion() ); >> }

>>
>> if ( !suppressSource( config ) && StringUtils.isEmpty(
>> config.getSourceVersion() ) )
>>

{ >> // If omitted, later JDKs complain about a 1.1 target >> args.add( "-source" ); >> args.add( "1.3" ); >> }

>>
>> Is there any particular reason why target is set to 1.1 here? IMHO, it
>> breaks the rule of least surprise for I am certainly expecting that the
>> generated byte code by default has the version of the JDK I'm using the
>> compiler of. The comment "Required, or it defaults to the target of your
>> JDK" doesn't give any reason. Does anybody know, why this default is set?
>>
>> At least it should be mentioned on
>> http://maven.apache.org/plugins/maven-compiler-plugin/howto.html to make
>> it obvious to users. Otherwise people might have problems and need a
>> long time to find out what's going on (see
>> http://www.nabble.com/Odd-Compilation-Issue-tf1566644s177.html#a4287495
>> for an example).
>>
>> Regards,
>> Gisbert

Issue Links

• relates to: MCOMPILER-6 improve documentation