[MCOMPILER-581] Create second default execution "default-generate-sources" for APT

[jira-importer]

Benjamin Marwell opened MCOMPILER-581 and commented

Starting with version 4.0.0 of this plugin for use with Maven 4+, the following changes should be incorporated to align the compilation process with the process designed by the OpenJDK javac team:

• Modify default-compile to use proc:none by default
• Create a new goal default-generate-sources and use proc:only

This will align the compilation process with the default javac use.

Rationale

Before JDK 21+, no "proc:full" was available and implicitly used when no proc:* was set.
However, starting with JDK 21, proc:full was introduced and not specifying proc:* will now trigger a warning.

Alternatives

Keep one phase but specify proc:full whenever APTs are in the CP or used as a compiler-plugin dependency/path or when APT classes are explicitly given.

Drawbacks of this approach

TODO: document drawbacks of this approach and of the alternatives.

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No further details from MCOMPILER-581

[jira-importer]

Tamas Cservenak commented

How about something along these lines:

• create 2 new mojos "proc" and "test-proc" (or apt or whatever) that automatically binds to "generate-sources" and "generate-test-sources" phases: they use proc:only
• add new configuration to AbstractCompilerMojo like "two phase APT" (boolean) defaults to false, keep today functionality, works as now
• behavior change 1: if "two phase APT" is false, the two new mojos just skip (like skip would be set), they immediately exit doing nothing and existing compile and test-compile mojos do whatever they did before.
• behavior change 2: "if two phase APT" is true, existing compiler mojo use proc:none (maybe fail if proc explicitly configured?), and the two new mojos activate and run using {}proc:only{}.

Am unsure why we need Maven4 for change like this.