Regression compiling Java in 0.5.0

[dfabulich]

This repository https://github.com/dfabulich/raw-list-bug builds without error in Bazel 0.4.5 when I run bazel build example, but fails to build in Bazel 0.5.0rc3

build failure message

ERROR: /private/tmp/raw-list-bug/BUILD:1:1: Building example.jar (1 source file) failed: Worker process sent response with exit code: 1.
src/main/java/com/redfin/Example.java:8: error: reference to newArrayList is ambiguous
		newArrayList(newLinkedHashSet(new ArrayList()));
		^
  both method <E#1>newArrayList(Iterable<? extends E#1>) in Example and method <E#2>newArrayList(Iterator<? extends E#2>) in Example match
  where E#1,E#2 are type-variables:
    E#1 extends Object declared in method <E#1>newArrayList(Iterable<? extends E#1>)
    E#2 extends Object declared in method <E#2>newArrayList(Iterator<? extends E#2>)
Target //:example failed to build

It seems like this must be a bug in the compiler; the code is using a raw LinkedHashSet, which is an Iterable, but it is not an Iterator.

The code compiles just fine with Oracle's javac compiler javac 1.8.0_112

Environment info

• Operating System:
  macOS Sierra 10.12.4

• Bazel version (output of bazel info release):
  release 0.5rc3 (it works with release 0.4.5)

I tried both the 0.5 version with an embedded JDK and without an embedded JDK, to see if that has an effect; it failed in both versions of Bazel 0.5 with identical error messages.

[kchodorow]

@cushon, could you take a look?

[cushon]

I think this is going to be fixed by https://bazel-review.googlesource.com/c/10990/

[cushon]

Verified:

import java.util.*;
abstract class T {
  abstract <E> ArrayList<E> newArrayList(Iterable<? extends E> elements);
  abstract <E> ArrayList<E> newArrayList(Iterator<? extends E> elements);
  abstract <E> LinkedHashSet<E> newLinkedHashSet(Iterable<? extends E> elements);
  {
    newArrayList(newLinkedHashSet(new ArrayList()));
  }
}

Before:

T.java:7: error: reference to newArrayList is ambiguous
    newArrayList(newLinkedHashSet(new ArrayList()));
    ^
  both method <E#1>newArrayList(Iterable<? extends E#1>) in T and method <E#2>newArrayList(Iterator<? extends E#2>) in T match
  where E#1,E#2 are type-variables:
    E#1 extends Object declared in method <E#1>newArrayList(Iterable<? extends E#1>)
    E#2 extends Object declared in method <E#2>newArrayList(Iterator<? extends E#2>)
Note: T.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
1 error

After:

Note: T.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

[dfabulich]

Wait a minute, wait a minute. Bazel 0.5 is using an unreleased Java 9 compiler? While I'm glad that upgrading the compiler to another unreleased Java 9 compiler fixed this bug, this can't be the right thing. https://groups.google.com/d/msg/bazel-discuss/LUfkHkCYOoE/4-Y6ni9DBgAJ