RFR: 8290041: ModuleDescriptor.hashCode is inconsistent

[Alan Bateman]

On Sat, 6 Aug 2022 08:08:43 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

> Can I please get a review of this change which proposes to fix https://bugs.openjdk.org/browse/JDK-8290041? 
> 
> As noted by the reporter, the current implementation is buggy since the calculation can result in a different value of the hashcode depending on the order of iteration of the `Modifier`s. The commit in this PR changes that computation to produce consistent result irrespective of the order in which the `Modifier`s (enum) is iterated upon.
> 
> A new test has been added which reproduces the issue and verifies the fix.

test/jdk/java/lang/module/ModuleDescriptorHashCodeTest.java line 71:

> 69:      */
> 70:     @Test
> 71:     public void testModifiersOrdering() throws Exception {

Are you planning to expand the test to cover Requires.Modifier and Exports.Modifier too?

test/jdk/java/lang/module/ModuleDescriptorHashCodeTest.java line 76:

> 74:         // important to use Set.of() (i.e. backed by immutable set) to reproduce the issue
> 75:         final Set<ModuleDescriptor.Opens.Modifier> mod1 = Set.of(
> 76:                 ModuleDescriptor.Opens.Modifier.SYNTHETIC, ModuleDescriptor.Opens.Modifier.MANDATED);

These should probably be "mods1" and "mods2" rather than "mod1" and "mod2" as they are a set of modifiers rather than a single modifier.

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PR: https://git.openjdk.org/jdk/pull/9790