PY-35961 Report missing parentheses in return/yield depending on language version

Previously it was done unconditionally for all Python versions in StarAnnotator.
I moved the corresponding checks from there to CompatibilityVisitor so that
it was clear in which particular versions it's mandatory.

GitOrigin-RevId: 205de8768431445baed98aecd5f9820efe28d281

python/src/com/jetbrains/python/validation/CompatibilityVisitor.java

@@ -157,6 +157,25 @@ public abstract class CompatibilityVisitor extends PyAnnotator {
       registerForAllMatchingVersions(level -> level.isOlderThan(LanguageLevel.PYTHON35) && registerForLanguageLevel(level),
                                      " not support starred expressions in tuples, lists, and sets",
                                      node);
+      final PsiElement container = PsiTreeUtil.skipParentsOfType(node, PyParenthesizedExpression.class);
+      if (container instanceof PyTupleExpression) {
+        final PsiElement tupleParent = container.getParent();
+        if (tupleParent instanceof PyReturnStatement) {
+          registerForAllMatchingVersions(level -> level.isAtLeast(LanguageLevel.PYTHON35) &&
+                                                  level.isOlderThan(LanguageLevel.PYTHON38) &&
+                                                  registerForLanguageLevel(level),
+                                         " not support unpacking without parentheses in return statements",
+                                         node);
+        }
+
+        if (tupleParent instanceof PyYieldExpression && !((PyYieldExpression)tupleParent).isDelegating()) {
+          registerForAllMatchingVersions(level -> level.isAtLeast(LanguageLevel.PYTHON35) &&
+                                                  level.isOlderThan(LanguageLevel.PYTHON38) &&
+                                                  registerForLanguageLevel(level),
+                                         " not support unpacking without parentheses in yield statements",
+                                         node);
+        }
+      }
     }
   }
 

python/src/com/jetbrains/python/validation/StarAnnotator.java

@@ -16,8 +16,9 @@
 package com.jetbrains.python.validation;
 
 import com.intellij.psi.PsiElement;
+import com.intellij.psi.util.PsiTreeUtil;
 import com.jetbrains.python.codeInsight.functionTypeComments.psi.PyParameterTypeList;
-import com.jetbrains.python.psi.PyReturnStatement;
+import com.jetbrains.python.psi.PyParenthesizedExpression;
 import com.jetbrains.python.psi.PyStarExpression;
 import com.jetbrains.python.psi.PyTupleExpression;
 import com.jetbrains.python.psi.PyYieldExpression;
@@ -40,10 +41,13 @@ public class StarAnnotator extends PyAnnotator {
       return false;
     }
 
-    final PsiElement parent = starExpression.getParent();
-    if (parent instanceof PyTupleExpression && (parent.getParent() instanceof PyReturnStatement ||
-                                                parent.getParent() instanceof PyYieldExpression)) {
-      return false;
+    // Additional contexts where unpacking is prohibited depending on the language version are covered in CompatibilityVisitor.
+    final PsiElement parent = PsiTreeUtil.skipParentsOfType(starExpression, PyParenthesizedExpression.class);
+    if (parent instanceof PyTupleExpression) {
+      final PsiElement tupleParent = parent.getParent();
+      if (tupleParent instanceof PyYieldExpression && ((PyYieldExpression)tupleParent).isDelegating()) {
+        return false;
+      }
     }
     return true;
   }

python/testData/highlighting/unpackingInNonParenthesizedTuplesInReturnAndYield.py

@@ -0,0 +1,4 @@
+def func(xs):
+    yield 42, *xs
+    yield from 42, <error descr="Can't use starred expression here">*xs</error>
+    return 42, *xs

python/testData/highlighting/unpackingInNonParenthesizedTuplesInReturnAndYieldBefore38.py

@@ -0,0 +1,4 @@
+def func(xs):
+    yield 42, <error descr="Python version 3.5 does not support unpacking without parentheses in yield statements">*xs</error>
+    yield from 42, <error descr="Can't use starred expression here">*xs</error>
+    return 42, <error descr="Python version 3.5 does not support unpacking without parentheses in return statements">*xs</error>

python/testData/highlighting/unpackingStar.py

@@ -8,12 +8,3 @@ if <error descr="Can't use starred expression here">*x</error>:
 
 1 + (<error descr="Can't use starred expression here">*x</error>)
 1 + (*x,)
-
-
-def f(x):
-    return x, <error descr="Can't use starred expression here">*x</error>
-
-
-def g(x):
-    yield from x, <error descr="Can't use starred expression here">*x</error>
-    yield x, <error descr="Can't use starred expression here">*x</error>

python/testData/inspections/PyCompatibilityInspection/unpackingInNonParenthesizedTuplesInReturnAndYield.py

@@ -0,0 +1,7 @@
+def gen(xs):
+    yield 42, <warning descr="Python version 2.6, 2.7, 3.4 do not support starred expressions in tuples, lists, and sets"><warning descr="Python version 3.5, 3.6, 3.7 do not support unpacking without parentheses in yield statements">*xs</warning></warning>
+    <warning descr="Python version 2.6, 2.7 do not support this syntax. Delegating to a subgenerator is available since Python 3.3; use explicit iteration over subgenerator instead.">yield from 42, <error descr="Can't use starred expression here"><warning descr="Python version 2.6, 2.7, 3.4 do not support starred expressions in tuples, lists, and sets">*xs</warning></error></warning>
+
+
+def func(xs):
+    return 42, <warning descr="Python version 2.6, 2.7, 3.4 do not support starred expressions in tuples, lists, and sets"><warning descr="Python version 3.5, 3.6, 3.7 do not support unpacking without parentheses in return statements">*xs</warning></warning>

python/testSrc/com/jetbrains/python/PythonHighlightingTest.java

@@ -263,6 +263,16 @@ public class PythonHighlightingTest extends PyTestCase {
     doTest(LanguageLevel.PYTHON35, false, false);
   }
 
+  // PY-35961
+  public void testUnpackingInNonParenthesizedTuplesInReturnAndYieldBefore38() {
+    doTest(LanguageLevel.PYTHON35, false, false);
+  }
+
+  // PY-35961
+  public void testUnpackingInNonParenthesizedTuplesInReturnAndYield() {
+    doTest(LanguageLevel.PYTHON38, false, false);
+  }
+
   // PY-19927
   public void testMagicMethods() {
     EditorColorsScheme scheme = createTemporaryColorScheme();

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

@@ -252,6 +252,11 @@ public class PyCompatibilityInspectionTest extends PyInspectionTestCase {
     );
   }
 
+  // PY-35961
+  public void testUnpackingInNonParenthesizedTuplesInReturnAndYield() {
+    doTest(LanguageLevel.PYTHON38);
+  }
+
   private void doTest(@NotNull LanguageLevel level) {
     runWithLanguageLevel(level, this::doTest);
   }