error-prone bug in ComparableType check

[benjaminp]

Here's some apparently buggy error-prone behavior:

$ touch WORKSPACE
$ cat X.java
package com.example;

class C implements Comparable<C> {
   @Override
    public int compareTo(C o) {
        return 0;
    }
}

public class X {}
$ cat BUILD
java_library(
    name = 'X',
    srcs = ['X.java'],
)
$ bazel build //:X
$ ~/bin/bazel --batch build :X 
INFO: Analyzed target //:X (18 packages loaded, 322 targets configured).
INFO: Found 1 target...
ERROR: BUILD:1:13: Building libX.jar (1 source file) failed (Exit 1)
X.java:3: error: [ComparableType] Comparable should not be raw
class C implements Comparable<C> {
^
    (see https://errorprone.info/bugpattern/ComparableType)
Target //:X failed to build
Use --verbose_failures to see the command lines of failed build steps.
INFO: Elapsed time: 3.994s, Critical Path: 1.73s
INFO: 0 processes.
FAILED: Build did NOT complete successfully

I'm reporting this here rather than https://github.com/google/error-prone because I can't reproduce it with raw javac:

$ javac   -XDcompilePolicy=simple   -processorpath error_prone_core-2.4.0-with-dependencies.jar:dataflow-shaded-3.1.2.jar:jFormatString-3.0.0.jar:threeten-extra-1.5.0.jar   '-Xplugin:ErrorProne  -Xep:ComparableType:ERROR'   X.java
$

[davido]

/Cc @cushon .

[cushon]

@comius

If you include -XDcompilePolicy=simple (or -XDcompilePolicy=byfile) it doesn't repro with Bazel either:

$ bazel build :X 
...
X.java:3: error: [ComparableType] Comparable should not be raw
class C implements Comparable<C> {
^
    (see https://errorprone.info/bugpattern/ComparableType)
$ bazel build --javacopt=-XDcompilePolicy=simple :X
...
Build completed successfully

Error Prone doesn't work with the default policy. The usual Error Prone entry point has a check for that, but the Bazel integration doesn't do an equivalent check: https://github.com/google/error-prone/blob/650cbfda0d9f53eebf04154c0ed3c4db27d5bca7/check_api/src/main/java/com/google/errorprone/BaseErrorProneJavaCompiler.java#L162

There's a javac bug that affects the byfile policy too, but the javac we redistribute has a fix for that: google/error-prone-javac@94c6b72

Bazel should be passing -XDcompilePolicy=simple in the default toolchain (or byfile depending on the support level of stock javac).