Add an option to javac to disable inlining of static final variables (to be used by programmers during development phase)

[Remi Forax]

----- Mail original -----
> De: "Behrang Saeedzadeh" <behrangsa at gmail.com>
> À: "compiler-dev" <compiler-dev at openjdk.java.net>, "discuss" <discuss at openjdk.java.net>
> Envoyé: Mercredi 10 Juin 2020 16:27:27
> Objet: Add an option to javac to disable inlining of static final variables (to be used by programmers during
> development phase)

> Hi,

Hi,

> 
> I guess inlining of static variables [1] is one of the main causes that
> during our day to day coding activities, we have to do a full recompile
> (e.g. `mvn clean ...`) every time a constant that is referenced throughout
> the code is changed.
> 
> There are a few ugly tricks to prevent the constants from getting inlined,
> but a compiler option that we can pass to javac that produces a warning
> message that can be used while we program locally could reduce the need to
> run `mvn clean ...`, `gradle clean ...`, etc.
> 
> Another option could be [2] adding some metadata to classes that reference
> constants to record where the constant is coming from that could allow
> build tools recompile all such classes when the constant changes.
> [1]
> https://docs.oracle.com/javase/specs/jls/se14/html/jls-13.html#jls-13.4.9.
> [2] If the class file format permits that.

It's already done by javac, it register all the classes of the static final fields it depends in the constant pool (the dictionary pat of the classfile format).
Gradle (the recent versions) uses this information but not Maven, so the question is more how to improve Maven to compute the graph of dependencies at the file level.

There is also a kind of quick hack if you have a multi-modules project, you can read the module-info.java to get the graph of modules to find the dependency at module level,
you can then use javac to read the module-info.java and the JDK API to create the module and let the JDK resolve the graph for you.
The build of the OpenJDK does that with great success.

> 
> 
> --
> Best regards,
> Behrang Saeedzadeh

regards,
Rémi