PY-83118 Forward Reference Causes Import to Be Incorrectly Removed in PyCharm 2025.2

(cherry picked from commit fcf27e5c97e12498bc1c630f43e0a0876faba408)

IJ-CR-172300

GitOrigin-RevId: cd4e80d21dfaf85312c2ac9b1944f04307bb40d4

python/python-psi-impl/src/com/jetbrains/python/inspections/PyUnusedImportsInspection.kt

@@ -91,6 +91,9 @@ class PyUnusedImportsInspection : PyInspection() {
 
     override fun visitPyElement(node: PyElement) {
       super.visitPyElement(node)
+      if (node is PsiLanguageInjectionHost) {
+        processInjection(node)
+      }
       if (node is PyReferenceOwner) {
         val resolveContext = PyResolveContext.defaultContext(myTypeEvalContext)
         processReference(node, node.getReference(resolveContext))

python/testData/inspections/unusedImport/injectedImportUsage/injectedImportUsage.py

@@ -0,0 +1,7 @@
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from mymodule import SomeClass
+
+def func(x: "SomeClass") -> None:
+    ...

python/testData/inspections/unusedImport/injectedImportUsage/mymodule.py

@@ -0,0 +1,2 @@
+class SomeClass:
+    pass

python/testSrc/com/jetbrains/python/inspections/PyUnusedImportTest.java

@@ -83,6 +83,11 @@ public class PyUnusedImportTest extends PyTestCase {
     doTest();
   }
 
+  // PY-83075
+  public void testInjectedImportUsage() {
+    doTest("injectedImportUsage.py");
+  }
+
   // PY-22620
   public void testTupleTypeCommentsUseImportsFromTyping() {
     doTest();