RFR: 8263614: javac allows local variables to be accessed from a static context

[Vicente Romero]

javac breaks with NPE if compiles this code:


public class LocalClasses {
    public static void main(String[] args) {
        int i = 5;
        class Local {
            static void m() {
                System.out.println("Value of i = " + i);
            }
        }
        Local.m();
    }
} 


actually the compiler should issue a compiling error as local variable `i` is being accessed from a static context. Please review this fix to address this issue. Some notes:

`com.sun.tools.javac.comp.AttrContext.staticLevel` keeps a the number of nested static contexts but this calculation doesn't consider static type declarations. This is because static declaration doesn't introduce a static context. But if they have a static modifier, even if implicit as it is for local records, then this affects what variables, type variables, etc are accessible from the body of the static type declaration. For this reason I have used an `adjusted` static level that takes static type declarations into account.

TIA

-------------

Commit messages:
 - 8263614: Referring to non-final variable from a static member embedded in a local class generates an NPE while compiling

Changes: https://git.openjdk.java.net/jdk/pull/4004/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4004&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8263614
  Stats: 109 lines in 2 files changed: 89 ins; 12 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4004.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4004/head:pull/4004

PR: https://git.openjdk.java.net/jdk/pull/4004