[MCOMPILER-499] Display recompilation causes

[ledoyen]

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// TODO

[olamy]

sounds like a good idea!
But I wonder if it could be better to have this not displayed per default (as it can be very verbose)
maybe a flag such maven.compiler.showRecompilationCause?

[ledoyen]

Notice that it is a draft, as I did not take the time to open a Jira ticket, clean the code and write tests.
However, I used the custom version on a big multi-module project to troubleshoot unwanted re-compilation and it works as intended.

That being said, to answer your concern, I introduced the flag maven.compiler.showCompilationChanges (defaulted to false) to avoid the verbose display when unwanted, and to keep the current behavior by default.

[olamy]

@ledoyen thanks! and sorry for the gh actions failure but oh we do not pay for support and don't know what is the issue :)

[olamy]

issue created as https://issues.apache.org/jira/browse/MCOMPILER-499

[olamy]

not sure if you want to have a look at my proposed changes or move forward with this PR.
otherwise I will do it.
thanks

[olamy]

we cannot see it in this GH ui diff but we go in this path only if ( getLog().isDebugEnabled() ) this must be changed to something such
if ( !staleSources.isEmpty() && (getLog().isDebugEnabled() || showCompilationChanges))
I guess the idea is to display those files when using -Dmaven.compiler.showCompilationChanges=true but without using full debug with -X

[olamy]

Suggested change

	String[] inputFileNames = new String[ inputFiles.size() ];
	String[] inputFileNames = inputFiles.stream().map(File::getAbsolutePath).toArray(String[]::new);

[olamy]

simply replace the block with a single line. yup even Maven can use modern syntax 😜

[olamy]

changes done in another PR #143