PY-50642 Don't build stubs for elements in unreachable if-branches

GitOrigin-RevId: 2fd1fb6777d80f436a495ff5eca08249bab9d21a

python/python-psi-impl/src/com/jetbrains/python/psi/PyFileElementType.java

@@ -60,7 +60,7 @@ public class PyFileElementType extends IStubFileElementType<PyFileStub> {
   @Override
   public int getStubVersion() {
     // Don't forget to update versions of indexes that use the updated stub-based elements
-    return 104;
+    return 105;
   }
 
   @Override

python/python-psi-impl/src/com/jetbrains/python/psi/impl/stubs/PyFileStubBuilder.java

@@ -20,9 +20,9 @@ import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.stubs.DefaultStubBuilder;
 import com.intellij.psi.stubs.StubElement;
-import com.jetbrains.python.psi.PyFile;
-import com.jetbrains.python.psi.PyIfStatement;
-import com.jetbrains.python.psi.PyUtil;
+import com.jetbrains.python.psi.*;
+import com.jetbrains.python.psi.impl.PyEvaluator;
+import one.util.streamex.StreamEx;
 import org.jetbrains.annotations.NotNull;
 
 
@@ -38,7 +38,36 @@ public class PyFileStubBuilder extends DefaultStubBuilder {
 
   @Override
   public boolean skipChildProcessingWhenBuildingStubs(@NotNull ASTNode parent, @NotNull ASTNode node) {
-    PsiElement psi = parent.getPsi();
-    return psi instanceof PyIfStatement && PyUtil.isIfNameEqualsMain((PyIfStatement)psi);
+    PsiElement parentPsi = parent.getPsi();
+    if (parentPsi instanceof PyIfStatement && PyUtil.isIfNameEqualsMain((PyIfStatement)parentPsi)) {
+      return true;
+    }
+    if (parentPsi instanceof PyIfStatement ifStatement && node.getPsi() instanceof PyStatementPart part) {
+      return isAlwaysUnreachable(ifStatement, part);
+    }
+    return false;
+  }
+
+  private static boolean isAlwaysUnreachable(@NotNull PyIfStatement ifStatement, @NotNull PyStatementPart part) {
+    assert part.getParent() == ifStatement;
+
+    for (PyIfPart ifPart : StreamEx.of(ifStatement.getIfPart()).append(ifStatement.getElifParts())) {
+      if (ifPart == part) {
+        break;
+      }
+      Boolean result = PyEvaluator.evaluateAsBooleanNoResolve(ifPart.getCondition());
+      if (result == Boolean.TRUE) {
+        return true;
+      }
+    }
+
+    if (part instanceof PyIfPart ifPart) {
+      Boolean result = PyEvaluator.evaluateAsBooleanNoResolve(ifPart.getCondition());
+      if (result == Boolean.FALSE) {
+        return true;
+      }
+    }
+
+    return false;
   }
 }

python/testData/intentions/PyAnnotateVariableTypeIntentionTest/AnnotationImportTypingOptional/lib.py

@@ -1,4 +1,4 @@
-if True:
+if input():
     foo = 42
 else:
     foo = None

python/testData/intentions/PyAnnotateVariableTypeIntentionTest/AnnotationImportTypingUnion/lib.py

@@ -1,4 +1,4 @@
-if True:
+if input():
     foo = 42
 else:
     foo = 'spam'

python/testSrc/com/jetbrains/python/Py3TypeTest.java

@@ -3348,6 +3348,23 @@ public class Py3TypeTest extends PyTestCase {
       """);
   }
 
+  // PY-50642
+  public void testTypeCheckingMultiFile() {
+    myFixture.addFileToProject("mod.py", """
+      import typing
+
+      if not not typing.TYPE_CHECKING:
+          v: int = -1
+      else:
+          v: str = 'ab'
+      """);
+
+    doTest("int", """
+      from mod import v
+      expr = v
+      """);
+  }
+
   // PY-73958
   public void testNoStackOverflow() {
     doTest("Foo", """