JDK level compilation switched to v7 for Eclipse m2e

[axel3rd]

Since commit ea5e38c, JDK v7 is used
for compilation.
Some class (Files, Path, ...) are now used and require JDK v7.
This change is mainly to link a JDK v7 when Eclipse m2e is used (v6 used
before, so compilation problem, manuel update required).

[michael-o]

The PR is incomplete to me. Look at 6397c3e, two new classes have been introduced. They can be easily deprecated or removed. They also maybe other spots.

[rfscholte]

labelled as bug? I would say enhancement...

[michael-o]

I don't thing so because enforcer requires 1.7. Why should MCOMPILER require 1.6 only? This looks like a mismatch or bug. Unless I do not fully understand the issue.

[axel3rd]

two new classes have been introduced

Good catch, thanks.

• I will delete Java7Detector (if v7 considered as minimal level version)
• Java7FileUtil has been already deleted previously
• Perhaps NioFiles should be reviewed

Unless I do not fully understand the issue.

Basically this feature was to have the correct JDK version linked in Eclipse when project is imported :-)

[axel3rd]

DirectoryScanner.isSymbolicLink seems bugged: only parent tested, not the complete file => should be

1. fixed or deleted (NioFiles.isSymbolicLink could be now used natively by end users) ?
2. and :
   1. In a dedicated PR
   2. In a separated commit of PR
   3. In the globale commit of PR
      ?

[michael-o]

@rfscholte that's the bug:

$ mvn help:effective-pom | grep maven.compiler.
    <maven.compiler.source>1.6</maven.compiler.source>
    <maven.compiler.target>1.6</maven.compiler.target>

[michael-o]

@axel3rd Incomplete tests should be separate PR. NioFiles shall be deprecated because they are public.

[rfscholte]

I don't thing so because enforcer requires 1.7. Why should MCOMPILER require 1.6 only?

This is intended. By using source+target all classes get the right byte-code version and can be used by JDK. However, by compiling with JDK 7 we can classes from this distribution. Normally you would call it "leaking" and the animal-sniffer-maven-plugin prevents you from doing so, but now we are using this feature. Java 9 comes with a better option: JEP 247: Compile for Older Platform Versions

[axel3rd]

Incomplete tests should be separate PR.

Ok

NioFiles shall be deprecated because they are public.

After reviewing the content, perhaps could stay unchanged. This is an utility class who "simplify" the usage of Files and Path (with usage if File).

[michael-o]

@rfscholte Makes sense now, though ugly. Will be leave at 6 now or move to 7? If not, we can close this PR.

[rfscholte]

Let's call it forward compatibility :) I'm not sure if this is the right moment to require Java 7, Plexus Utils is used a lot.

[michael-o]

@axel3rd I think this PR has to be dropped because it won't do what we want. I think the best is a profile for m2e action to override the javaVersion.

[axel3rd]

PR updated with java 1.7 compilation level restricted to m2e Eclipse plugin usage (title updated).
For , DirectoryScanner.isSymbolicLink bug, see #28.

[michael-o]

@rfscholte Any objections to merge this? Looks good to me now.

[rfscholte]

I see that Eclipse is trying to pick the best matching JDK. You'll only see this issue when you have JDK6 installed. However, if you run any goal from the IDE, its bytecode version will be wrong.
This profile is only there to fool Eclipse. Eclipse should respect the requireJavaVersion enforcer-rule instead.
So I'm -0. I don't think it's worth it (number of developers which also have JDK6 is to low). But to prevent the compilation error of NioFiles in Eclipse, I would prefer proper Javadoc in that class. The solution would be to manually change the JRE System Library.

[michael-o]

@rfscholte Agreed. Though, Eclipse ignores the Enforcer rule here. @axel3rd Do you have JDK 6 installed?

[axel3rd]

@michael-o : Yes, I have the JDK 6 configured in my Eclipse. I have updated the profile comment with the exact cause. Even if this is a m2e bug, this workaround can't be added ? It is boring to configure the JRE System Library to JavaSE-1.7 manually under Eclipse on any checkout ; But I can continue to do that if this profile is not sustainable ...

[axel3rd]

Thanks :-)