Find Usages(⌥ F7) not working.

[odk211]

Describe the bug
Find Usages(⌥ F7) not working in Plugin Version: 12.0.1 and IDEA 2021.3.
I rollbacked IDEA version to 2021.2.3 and It worked.

To Reproduce

1. Write

defmodule Foo do
  def foo, do: "foo"
  def bar, do: foo()
  def baz, do: foo()
end

2. Move Cursor to foo()
3. Do Find Usages(⌥ F7).
4. Find window is not activated.

Logs
No pop up events.

System

Plugin Version: 12.0.1
Application: IntelliJ IDEA Ultimate Edition (2021.3)
Operating System: Mac OS X (11.6.1)

[KronicDeth]

I swear JetBrains breaks the Find Usage API in every version of the IDEs now. They probably messed with the TargetElementEvaluator API usage again.

[KronicDeth]

  public void findUsages(@NotNull PsiElement psiElement, @Nullable PsiFile scopeFile, FileEditor editor, boolean showDialog, @Nullable("null means default (stored in options)") SearchScope searchScope) {
    ApplicationManager.getApplication().assertIsDispatchThread();
    FindUsagesHandler handler = getFindUsagesHandler(psiElement, showDialog ? OperationMode.DEFAULT : OperationMode.USAGES_WITH_DEFAULT_OPTIONS);
    if (handler == null) return;

https://github.com/JetBrains/intellij-community/blob/bb6036b52b52e67272543349ff2bb9b939275ee6/platform/lang-impl/src/com/intellij/find/findUsages/FindUsagesManager.java#L193-L194

It can't find the FindUsagesHandler and so returns before trying to find anything.

[KronicDeth]

That code was last change 2 years ago, so it's something deeper messing it up now.

[KronicDeth]

It annoys me to no end that Find Usages is broken, but the related highlighting of usages is not as foo is highlighted correctly when any of the foos have the cursor on them.

[KronicDeth]

I think it is related to the new SearchTargetVariantsDataRule as that supplies the default value for the targets, which is giving the wrong element.

[odk211]

@KronicDeth Thank you for great work! ❤️ I installed plugin v12.1.0 and check this issue's how to reproduce. but it shows like No Usage found.
I checked this combination.

• IDEA 2021.2.3, plugin v12.1.0 -> No Usage found
• IDEA 2021.3.1, plugin v12.1.0 -> No Usage found
• IDEA 2021.2.3, plugin v12.0.1 -> 3 usage found