[groovy] dfa: treat null comparison as instanceof (IDEA-201672)

plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/psi/controlFlow/InstanceOfInstruction.java

@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.plugins.groovy.lang.psi.controlFlow;
 
 import com.intellij.openapi.util.Pair;
@@ -31,6 +17,8 @@ import org.jetbrains.plugins.groovy.lang.psi.controlFlow.impl.InstructionImpl;
 
 import java.util.Objects;
 
+import static org.jetbrains.plugins.groovy.lang.psi.util.PsiUtilKt.isNullLiteral;
+
 /**
  * @author peter
  */
@@ -75,6 +63,16 @@ public class InstanceOfInstruction extends InstructionImpl implements MixinTypeI
         return new Pair<>(left, type);
       }
     }
+    else if (element instanceof GrBinaryExpression) {
+      GrExpression left = ((GrBinaryExpression)element).getLeftOperand();
+      GrExpression right = ((GrBinaryExpression)element).getRightOperand();
+      if (isNullLiteral(right)) {
+        return Pair.create(left, PsiType.NULL);
+      }
+      else if (right != null && isNullLiteral(left)) {
+        return Pair.create(right, PsiType.NULL);
+      }
+    }
     return null;
   }
 

plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/psi/controlFlow/impl/ControlFlowBuilder.java

@@ -41,7 +41,8 @@ import org.jetbrains.plugins.groovy.lang.psi.util.PsiUtil;
 
 import java.util.*;
 
-import static org.jetbrains.plugins.groovy.lang.psi.GroovyElementTypes.T_ELVIS_ASSIGN;
+import static org.jetbrains.plugins.groovy.lang.psi.GroovyElementTypes.*;
+import static org.jetbrains.plugins.groovy.lang.psi.util.PsiUtilKt.isNullLiteral;
 
 /**
  * @author ven
@@ -559,6 +560,18 @@ public class ControlFlowBuilder extends GroovyRecursiveElementVisitor {
       processInstanceOf(expression, ((GrInExpression)expression).getNegationToken() != null);
       return;
     }
+    if (opType == T_EQ || opType == T_NEQ) {
+      if (isNullLiteral(right)) {
+        left.accept(this);
+        processInstanceOf(expression, opType == T_NEQ);
+        return;
+      }
+      else if (right != null && isNullLiteral(left)) {
+        right.accept(this);
+        processInstanceOf(expression, opType == T_NEQ);
+        return;
+      }
+    }
 
     if (opType != GroovyTokenTypes.mLOR && opType != GroovyTokenTypes.mLAND && opType != GroovyTokenTypes.kIN) {
       left.accept(this);

plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/psi/dataFlow/types/InferenceCache.java

@@ -12,6 +12,7 @@ import gnu.trove.TObjectIntHashMap;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.plugins.groovy.lang.psi.GrControlFlowOwner;
+import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrBinaryExpression;
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrExpression;
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrInstanceOfExpression;
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrReferenceExpression;
@@ -160,6 +161,7 @@ class InferenceCache {
     return PsiTreeUtil.findFirstParent(
       element,
       element1 -> !(element1.getParent() instanceof GrExpression)
+                  || element1 instanceof GrBinaryExpression
                   || element1 instanceof GrInstanceOfExpression
                   || isExpressionStatement(element1)
     );

plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/psi/util/psiUtil.kt

@@ -7,6 +7,7 @@ import com.intellij.psi.PsiMethod
 import com.intellij.psi.PsiParameter
 import org.jetbrains.plugins.groovy.lang.lexer.GroovyTokenTypes
 import org.jetbrains.plugins.groovy.lang.lexer.GroovyTokenTypes.kIN
+import org.jetbrains.plugins.groovy.lang.psi.GroovyElementTypes.KW_NULL
 import org.jetbrains.plugins.groovy.lang.psi.api.GroovyResolveResult
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.GrVariable
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.GrVariableDeclaration
@@ -14,11 +15,13 @@ import org.jetbrains.plugins.groovy.lang.psi.api.statements.clauses.GrForInClaus
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrExpression
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrOperatorExpression
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrReferenceExpression
+import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.literals.GrLiteral
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.params.GrParameter
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.params.GrParameterList
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.typedef.members.GrMethod
 import org.jetbrains.plugins.groovy.lang.psi.api.toplevel.imports.GrImportStatement
 import org.jetbrains.plugins.groovy.lang.psi.api.types.GrCodeReferenceElement
+import org.jetbrains.plugins.groovy.lang.psi.impl.statements.expressions.literals.GrLiteralImpl
 
 /**
  * @param owner modifier list owner
@@ -63,3 +66,7 @@ fun GrCodeReferenceElement.mayContainTypeArguments(): Boolean {
   val (parent, _) = skipParentsOfType<GrCodeReferenceElement>() ?: return true
   return parent !is GrImportStatement
 }
+
+fun GrExpression?.isNullLiteral(): Boolean {
+  return this is GrLiteral && GrLiteralImpl.getLiteralType(this) == KW_NULL
+}

plugins/groovy/test/org/jetbrains/plugins/groovy/lang/controlFlow/ControlFlowTest.groovy

@@ -106,6 +106,8 @@ class ControlFlowTest extends LightCodeInsightFixtureTestCase {
 
   void testIfInstanceofOr() { doTest() }
 
+  void testIfNullOrInstanceof() { doTest() }
+
   void testReturnMapFromClosure() { doTest() }
 
   void testSwitchInTryWithThrows() { doTest() }

plugins/groovy/test/org/jetbrains/plugins/groovy/lang/resolve/TypeInferenceTest.groovy

@@ -571,6 +571,58 @@ def foo(a) {
 ''', 'A'
   }
 
+  void 'test null or instanceof'() {
+    doTest '''\
+def foo(a) {
+    if (a == null || a instanceof String) {
+        <caret>a
+    }
+}
+''', JAVA_LANG_STRING
+  }
+
+  void 'test null or instanceof 2'() {
+    doTest '''\
+def foo(a) {
+    if (null == a || a instanceof String) {
+        <caret>a
+    }
+}
+''', JAVA_LANG_STRING
+  }
+
+  void 'test instanceof or null'() {
+    doTest '''\
+def foo(a) {
+    if (a == null || a instanceof String) {
+        <caret>a
+    }
+}
+''', JAVA_LANG_STRING
+  }
+
+  void 'test instanceof or null 2'() {
+    doTest '''\
+def foo(a) {
+    if (null == a || a instanceof String) {
+        <caret>a
+    }
+}
+''', JAVA_LANG_STRING
+  }
+
+  void 'test null or instanceof else'() {
+    doTest '''\
+def foo(a) {
+    if (a != null && a !instanceof String) {
+    
+    } else {
+        <caret>a
+    }
+}
+''', JAVA_LANG_STRING
+  }
+
   void 'test enum constant'() {
     doTest('''\
 import static MyEnum.*

plugins/groovy/testdata/groovy/controlFlow/ifNullOrInstanceof.test

@@ -0,0 +1,22 @@
+if (a == null || a instanceof String) {
+    a
+}
+-----
+0(1) element: null
+1(2) element: IF statement
+2(3) Condition Logical expression
+3(4) READ a
+4(5,7) Condition Relational expression, dependent: 2
+5(6) instanceof: a == null
+6(9)  Negating goto instruction, condition=4Relational expression
+7(8) instanceof: a == null
+8(14) element: Logical expression
+9(10) READ a
+10(11,13) Condition Instanceof expression
+11(12) instanceof: a instanceof String
+12(16)  Negating goto instruction, condition=10Instanceof expression
+13(14) instanceof: a instanceof String
+14(15) READ a
+15(16) element: Reference expression MAYBE_RETURN
+16(17) End element: IF statement
+17() element: null

plugins/groovy/testdata/groovy/controlFlow/try6.test

@@ -10,15 +10,19 @@ return url
 -----
 0(1) element: null
 1(2) element: IF statement
-2(3,10) READ url
-3(4) element: Open block
-4(11) WRITE url
-5(6) element: Catch clause
-6(7) WRITE e
-7(8) READ e
-8(9) ARGUMENTS element: NEW expression
-9(13) THROW. element: THROW statement
-10(11) End element: IF statement
-11(12) READ url
-12(13) element: RETURN statement
-13() element: null
+2(3) READ url
+3(4,6) Condition Relational expression
+4(5) instanceof: url == null
+5(14)  Negating goto instruction, condition=3Relational expression
+6(7) instanceof: url == null
+7(8) element: Open block
+8(15) WRITE url
+9(10) element: Catch clause
+10(11) WRITE e
+11(12) READ e
+12(13) ARGUMENTS element: NEW expression
+13(17) THROW. element: THROW statement
+14(15) End element: IF statement
+15(16) READ url
+16(17) element: RETURN statement
+17() element: null