IDEA-CR-42930: check that function/variable/import has been initialized before suggesting it for autocomplete

(cherry picked from commit aa11f609df36b2b1b3ce6079f17082bd2b6df9f7)

python/src/com/jetbrains/python/psi/impl/references/PyReferenceImpl.java

@@ -3,6 +3,7 @@ package com.jetbrains.python.psi.impl.references;
 
 import com.google.common.collect.Lists;
 import com.intellij.codeInsight.completion.CompletionUtil;
+import com.intellij.codeInsight.controlflow.ControlFlowUtil;
 import com.intellij.codeInsight.controlflow.Instruction;
 import com.intellij.codeInsight.lookup.LookupElement;
 import com.intellij.codeInsight.lookup.LookupElementBuilder;
@@ -10,6 +11,7 @@ import com.intellij.lang.ASTNode;
 import com.intellij.lang.annotation.HighlightSeverity;
 import com.intellij.openapi.util.Comparing;
 import com.intellij.openapi.util.Pair;
+import com.intellij.openapi.util.Ref;
 import com.intellij.openapi.util.TextRange;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.psi.*;
@@ -692,6 +694,30 @@ public class PyReferenceImpl implements PsiReferenceEx, PsiPolyVariantReference
             return false;
           }
         }
+      } else if (ScopeUtil.getScopeOwner(e) == ScopeUtil.getScopeOwner(element)) {
+        String name = null;
+        ScopeOwner scopeOwner = ScopeUtil.getScopeOwner(e);
+        if (e instanceof PsiNamedElement) {
+          name = ((PsiNamedElement) e).getName();
+        } else if (e instanceof PyImportElement) {
+          name = ((PyImportElement) e).getName();
+        } else if (e instanceof PyImportedNameDefiner && scopeOwner != null) {
+          Ref<Boolean> importFound = Ref.create(false);
+          Instruction[] instructions = ControlFlowCache.getControlFlow(scopeOwner).getInstructions();
+          int completionIndex = ControlFlowUtil.findInstructionNumberByElement(instructions, element);
+          ControlFlowUtil.iteratePrev(completionIndex, instructions, instruction -> {
+            if (instruction.getElement() == e) {
+              importFound.set(true);
+              return ControlFlowUtil.Operation.BREAK;
+            }
+            return ControlFlowUtil.Operation.NEXT;
+          });
+          return importFound.get();
+        }
+        if (name != null && scopeOwner != null) {
+          List<Instruction> defs = getLatestDefinitions(name, scopeOwner, element);
+          return !defs.isEmpty();
+        }
       }
       return true;
     }, null);

python/testData/completion/beforeImport/beforeImport.py

@@ -0,0 +1,3 @@
+m<caret>
+
+from source import my_foo

python/testData/completion/beforeImport/beforeImportAs.py

@@ -0,0 +1,3 @@
+m<caret>
+
+from source import my_foo as my_renamed_foo

python/testData/completion/beforeImport/beforeStarImport.py

@@ -0,0 +1,3 @@
+my_<caret>
+
+from source import *

python/testData/completion/beforeImport/source.py

@@ -0,0 +1,8 @@
+
+
+def my_foo():
+    pass
+
+
+def my_bar():
+    pass

python/testSrc/com/jetbrains/python/PythonCompletionTest.java

@@ -1425,6 +1425,80 @@ public class PythonCompletionTest extends PyTestCase {
     assertContainsElements(suggested, "'k1'", "'k2'");
   }
 
+  // PY-8302
+  public void testUndeclaredFunction() {
+    List<String> suggested = doTestByText("f<caret>\n" +
+                                        "\n" +
+                                        "def foo(yyy):\n" +
+                                        "  y = 1");
+    assertNotNull(suggested);
+    assertDoesntContain(suggested, "foo");
+  }
+
+  // PY-8302
+  public void testUninitializedVarBefore() {
+    List<String> suggested = doTestByText("f<caret>\n" +
+                                        "\n" +
+                                        "foo = \"something\"\n");
+    assertNotNull(suggested);
+    assertDoesntContain(suggested, "foo");
+  }
+
+  // PY-8302
+  public void testUninitializedVarOnSameLine() {
+    List<String> suggested = doTestByText("foo = f<caret>");
+    assertNotNull(suggested);
+    assertDoesntContain(suggested, "foo");
+  }
+
+  // PY-8302
+  public void testUninitializedVarOnMultiLine() {
+    List<String> suggested = doTestByText("foo = \"this is a string\"\\\n" +
+                                          "      \"on several lines\" + f<caret>");
+    assertNotNull(suggested);
+    assertDoesntContain(suggested, "foo");
+  }
+
+  // PY-8302
+  public void testUndeclaredClass() {
+    List<String> suggested = doTestByText("class AClass(A<caret>)");
+    assertNotNull(suggested);
+    assertDoesntContain(suggested, "AClass");
+  }
+
+  // PY-8302
+  public void testDeclaredClass() {
+    List<String> suggested = doTestByText("class AClass:\n" +
+                                          "    pass\n\n" +
+                                          "class BClass(A<caret>)");
+    assertNotNull(suggested);
+    assertContainsElements(suggested, "AClass");
+  }
+
+  // PY-8302
+  public void testBeforeImport() {
+    myFixture.configureByFiles("beforeImport/beforeImport.py", "beforeImport/source.py");
+    myFixture.completeBasic();
+    List<String> suggested = myFixture.getLookupElementStrings();
+    assertDoesntContain(suggested, "my_foo", "my_bar");
+  }
+
+  // PY-8302
+  public void testBeforeImportAs() {
+    myFixture.configureByFiles("beforeImport/beforeImportAs.py", "beforeImport/source.py");
+    myFixture.completeBasic();
+    List<String> suggested = myFixture.getLookupElementStrings();
+    assertDoesntContain(suggested, "my_renamed_foo");
+  }
+
+  // PY-8302
+  public void testBeforeStarImport() {
+    myFixture.configureByFiles("beforeImport/beforeStarImport.py", "beforeImport/source.py");
+    myFixture.completeBasic();
+    List<String> suggested = myFixture.getLookupElementStrings();
+    assertDoesntContain(suggested, "my_foo", "my_bar");
+  }
+
   private void assertNoVariantsInExtendedCompletion() {
     myFixture.copyDirectoryToProject(getTestName(true), "");
     myFixture.configureByFile("a.py");