[python] PY-86190: Enable missing interpreter warning on empty file.

PR: https://github.com/JetBrains/intellij-community/pull/3341

GitOrigin-RevId: 04c927e2c37a9a8c9ae0d5612efec4f1ea9b5b05

python/python-psi-impl/src/com/jetbrains/python/inspections/PyInspectionVisitor.java

@@ -27,6 +27,7 @@ import com.intellij.psi.PsiFile;
 import com.intellij.psi.impl.source.resolve.FileContextUtil;
 import com.intellij.util.ObjectUtils;
 import com.jetbrains.python.psi.PyElementVisitor;
+import com.jetbrains.python.psi.PyFile;
 import com.jetbrains.python.psi.resolve.PyResolveContext;
 import com.jetbrains.python.psi.types.TypeEvalContext;
 import org.jetbrains.annotations.NotNull;
@@ -80,7 +81,7 @@ public abstract class PyInspectionVisitor extends PyElementVisitor {
 
   protected final void registerProblem(@Nullable PsiElement element,
                                        @NotNull @InspectionMessage String message) {
-    if (element == null || element.getTextLength() == 0) {
+    if (!canRegisterProblem(element)) {
       return;
     }
     if (myHolder != null) {
@@ -91,7 +92,7 @@ public abstract class PyInspectionVisitor extends PyElementVisitor {
   protected final void registerProblem(@Nullable PsiElement element,
                                        @NotNull @InspectionMessage String message,
                                        LocalQuickFix @NotNull ... quickFixes) {
-    if (element == null || element.getTextLength() == 0) {
+    if (!canRegisterProblem(element)) {
       return;
     }
     if (myHolder != null) {
@@ -102,7 +103,7 @@ public abstract class PyInspectionVisitor extends PyElementVisitor {
   protected final void registerProblem(@Nullable PsiElement element,
                                        @NotNull @InspectionMessage String message,
                                        @NotNull ProblemHighlightType type) {
-    if (element == null || element.getTextLength() == 0) {
+    if (!canRegisterProblem(element)) {
       return;
     }
     if (myHolder != null) {
@@ -111,6 +112,18 @@ public abstract class PyInspectionVisitor extends PyElementVisitor {
     }
   }
 
+  private static boolean canRegisterProblem(@Nullable PsiElement element) {
+    if (element == null) {
+      return false;
+    }
+
+    if (element.getTextLength() > 0) {
+      return true;
+    }
+
+    return element instanceof PyFile;
+  }
+
   /**
    * The most full-blown version.
    *

python/testSrc/com/jetbrains/python/inspections/PyInterpreterInspectionTest.kt

@@ -14,6 +14,14 @@ class PyInterpreterInspectionTest : PyTestCase() {
   override fun getProjectDescriptor(): LightProjectDescriptor? = ourPyLatestDescriptor
 
   fun testNoInterpreterConfiguredShowsProblem() {
+    assertInterpreterWarning("test.py", "print('hello')\n")
+  }
+
+  fun testNoInterpreterConfiguredShowsProblemInEmptyFile() {
+    assertInterpreterWarning("__init__.py", "")
+  }
+
+  private fun assertInterpreterWarning(fileName: String, content: String) {
     val project = myFixture.project
     val module = myFixture.module
 
@@ -29,7 +37,7 @@ class PyInterpreterInspectionTest : PyTestCase() {
 
       val expectedMsg = PyPsiBundle.message("INSP.interpreter.no.python.interpreter.configured.for.module")
 
-      myFixture.configureByText("test.py", "print('hello')\n")
+      myFixture.configureByText(fileName, content)
       myFixture.enableInspections(PyInterpreterInspection::class.java)
 
       val highlights = myFixture.doHighlighting()