PY-17635 Complete parameter names in ":type" declaration of reST docstrings

python/src/com/jetbrains/python/codeInsight/completion/PyDocstringCompletionContributor.java

@@ -24,6 +24,7 @@ import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.PsiNamedElement;
 import com.intellij.psi.PsiReference;
+import com.intellij.psi.impl.source.resolve.reference.impl.PsiMultiReference;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.util.ProcessingContext;
 import com.jetbrains.python.documentation.docstrings.DocStringParameterReference;
@@ -78,7 +79,19 @@ public class PyDocstringCompletionContributor extends CompletionContributor {
           }
         }
       }
-      else if (reference instanceof DocStringParameterReference) {
+      // For reST declaration like ":param foo: int" "foo" is PsiMultiReference that combines DocStringParameterReference and DocStringTypeReference
+      else if (reference instanceof PsiMultiReference) {
+        for (PsiReference innerReference : ((PsiMultiReference)reference).getReferences()) {
+          addVariantsFromDocstringReference(innerReference, result);
+        }
+      }
+      else {
+        addVariantsFromDocstringReference(reference, result);
+      }
+    }
+
+    private static void addVariantsFromDocstringReference(@NotNull PsiReference reference, @NotNull CompletionResultSet result) {
+      if (reference instanceof DocStringParameterReference) {
         for (PyNamedParameter param : ((DocStringParameterReference)reference).collectParameterVariants()) {
           result.addElement(LookupElementBuilder.createWithIcon(param));
         }

python/testData/completion/paramNameInTypeDeclarationInRestDocstring.py

@@ -0,0 +1,4 @@
+def f(foo, bar):
+    """
+    :type f<caret>
+    """

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

@@ -509,6 +509,18 @@ public class PythonCompletionTest extends PyTestCase {
     });
   }
 
+  // PY-17635
+  public void testParamNameInTypeDeclarationInRestDocstring() {
+    runWithDocStringFormat(DocStringFormat.REST, new Runnable() {
+      @Override
+      public void run() {
+        final List<String> variants = doTestByFile();
+        assertNotNull(variants);
+        assertContainsElements(variants, "foo");
+      }
+    });
+  }
+
   public void testPep328Completion() {  // PY-3409
     myFixture.copyDirectoryToProject("pep328", "pep328");
     myFixture.configureByFile("pep328/package/subpackage1/moduleX.py");