-version produces "javac (version info not available)"

[cpovirk]

Since the default issue template suggests including the output of -version, I've noticed that, for a while now, the output of that has been:

javac (version info not available)

If I go all the way back to Checker Framework 2.10.0, I see:

javac 1.8.0-jsr308-2.4.0

But every version I had handy for testing from 2.11.0 onward has "version info not available."

(I wonder if ideally the version output would include the version of the Checker Framework itself?)

[wmdietl]

I had recently noticed something similarly.
Up to 2.11.0 we used our own jsr308-langtools compiler, in which we had added the Checker Framework version numbers.
We now use either the error-prone javac (if run on a Java 8 JVM) or the host javac (for a Java >=9 JVM).

For example, I get:

./checker/bin/javac -version
javac 11.0.7

because that's the host compiler version I seem to be using.

I don't think we can easily intercept how javac outputs the version number.
How about adding an -Aversion flag that we can use to output the Checker Framework version?

[wmdietl]

Implementation tasks:

• add a new key "version" to the set of supported options: https://github.com/typetools/checker-framework/blob/master/framework/src/main/java/org/checkerframework/framework/source/SourceChecker.java#L373
• in typeProcessingStart check for the new option: https://github.com/typetools/checker-framework/blob/master/framework/src/main/java/org/checkerframework/framework/source/SourceChecker.java#L762
• use messager to output the version
• make sure the version string gets updated automatically, using checker-framework-version and checker-framework-date magic https://github.com/typetools/checker-framework/blob/master/docs/developer/release/release.properties