JDK 9 change to symlink handling affects SourceFile attributes

Summary

Restore pre-JDK 9 behavior where the SourceFile attribute in the classfile was based on the user-provided file name, not on the canonical file name.

Problem

Consider example from the bug (JDK-8181897):

$ echo 'class Hello {}' > SOURCE
$ ln -s SOURCE Hello.java

JDK 8:

javac Hello.java && javap -v Hello |& grep 'Compiled from'
  Compiled from "Hello.java"

JDK 9:

javac Hello.java && javap -v Hello |& grep 'Compiled from'
  Compiled from "SOURCE" 

The SourceFile attribute is based on the real/canonical file name, instead of the user-provided name.

Solution

Restore the JDK 8 behavior, and use the user-provided file name as the basis for the SourceFile attribute.

Specification

The SourceFile attribute will be based on the user-provided file name, instead of the canonical file name.