IDEA-51686 Groovy syntax parser does not recognize that indexing using array returns a slice

plugins/groovy/src/org/jetbrains/plugins/groovy/lang/psi/impl/statements/expressions/path/GrIndexPropertyImpl.java

@@ -19,18 +19,19 @@ package org.jetbrains.plugins.groovy.lang.psi.impl.statements.expressions.path;
 import com.intellij.lang.ASTNode;
 import com.intellij.psi.*;
 import com.intellij.psi.util.InheritanceUtil;
-import com.intellij.psi.util.PsiUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.plugins.groovy.lang.psi.GroovyElementVisitor;
 import org.jetbrains.plugins.groovy.lang.psi.api.GroovyResolveResult;
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.arguments.GrArgumentList;
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrExpression;
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.path.GrIndexProperty;
-import org.jetbrains.plugins.groovy.lang.psi.api.statements.typedef.members.GrGdkMethod;
 import org.jetbrains.plugins.groovy.lang.psi.impl.GrTupleType;
 import org.jetbrains.plugins.groovy.lang.psi.impl.statements.expressions.GrExpressionImpl;
 import org.jetbrains.plugins.groovy.lang.psi.impl.statements.expressions.TypesUtil;
 
+import static com.intellij.psi.util.PsiUtil.substituteTypeParameter;
+import static org.jetbrains.plugins.groovy.lang.psi.util.PsiUtil.getSmartReturnType;
+
 /**
  * @author ilyas
  */
@@ -74,38 +75,41 @@ public class GrIndexPropertyImpl extends GrExpressionImpl implements GrIndexProp
           argTypes[i] = argType;
         }
 
-        if (thisType instanceof GrTupleType) {
+        if (thisType instanceof GrTupleType &&
+            argTypes.length == 1 &&
+            TypesUtil.isAssignable(PsiType.INT, argTypes[0], getManager(), getResolveScope())) {
           PsiType[] types = ((GrTupleType)thisType).getParameters();
           return types.length == 1 ? types[0] : null;
         }
 
         PsiType overloadedOperatorType = null;
-        final GroovyResolveResult[] candidates = TypesUtil.getOverloadedOperatorCandidates(thisType, "getAt", this, argTypes);
+        GroovyResolveResult[] candidates = TypesUtil.getOverloadedOperatorCandidates(thisType, "getAt", this, argTypes);
+        if (candidates.length != 1) {
+          candidates = TypesUtil.getOverloadedOperatorCandidates(thisType, "getAt", this, new PsiType[]{
+            new GrTupleType(argTypes, JavaPsiFacade.getInstance(getProject()), getResolveScope())});
+        }
         if (candidates.length == 1) {
           final PsiElement element = candidates[0].getElement();
           if (element instanceof PsiMethod) {
-            overloadedOperatorType = candidates[0].getSubstitutor().substitute(org.jetbrains.plugins.groovy.lang.psi.util.PsiUtil.getSmartReturnType((PsiMethod)element));
-            if (overloadedOperatorType != null && !(element instanceof GrGdkMethod)) {   //gdk 'getAt' methods don't have information about type parameters
-              return overloadedOperatorType;
-            }
+            overloadedOperatorType = candidates[0].getSubstitutor().substitute(getSmartReturnType((PsiMethod)element));
           }
         }
 
-        if (thisType instanceof PsiArrayType) {
-          PsiType componentType = ((PsiArrayType)thisType).getComponentType();
-          return TypesUtil.boxPrimitiveType(componentType, getManager(), getResolveScope());
+        PsiType componentType = null;
+        if (thisType instanceof PsiArrayType &&
+            argTypes.length == 1 &&
+            TypesUtil.isAssignable(PsiType.INT, argTypes[0], getManager(), getResolveScope())) {
+          componentType = TypesUtil.boxPrimitiveType(((PsiArrayType)thisType).getComponentType(), getManager(), getResolveScope());
+        }
+        else if (InheritanceUtil.isInheritor(thisType, CommonClassNames.JAVA_UTIL_MAP) && argTypes.length == 1) {
+          componentType = substituteTypeParameter(thisType, CommonClassNames.JAVA_UTIL_MAP, 1, true);
         }
 
-        if (InheritanceUtil.isInheritor(thisType, CommonClassNames.JAVA_UTIL_LIST)) {
-          PsiType iterType = PsiUtil.extractIterableTypeParameter(thisType, true);
-          if (iterType != null) return iterType;
+        if (overloadedOperatorType != null &&
+            (componentType == null || !TypesUtil.isAssignable(overloadedOperatorType, componentType, getManager(), getResolveScope()))) {
+          return overloadedOperatorType;
         }
-
-        if (InheritanceUtil.isInheritor(thisType, CommonClassNames.JAVA_UTIL_MAP)) {
-          return PsiUtil.substituteTypeParameter(thisType, CommonClassNames.JAVA_UTIL_MAP, 1, true);
-        }
-
-        return overloadedOperatorType;
+        return componentType;
       }
     }
     return null;

plugins/groovy/test/org/jetbrains/plugins/groovy/GrCompletionTestWithLibrary.groovy

@@ -58,4 +58,5 @@ class GrCompletionTestWithLibrary extends GroovyCompletionTestBase {
   public void testCategoryProperty() {doBasicTest()}
   public void testMultipleCategories() {doBasicTest()}
 
+  public void testArrayLikeAccessForList() throws Throwable {doBasicTest(); }
 }

plugins/groovy/test/org/jetbrains/plugins/groovy/GroovyCompletionTest.java

@@ -96,10 +96,6 @@ public class GroovyCompletionTest extends GroovyCompletionTestBase {
     doBasicTest();
   }
 
-  public void testArrayLikeAccessForList() throws Throwable {
-    doBasicTest();
-  }
-
   public void testArrayLikeAccessForMap() throws Throwable {
     doBasicTest();
   }

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

@@ -117,4 +117,9 @@ public class TypeInferenceTest extends GroovyResolveTestCase {
     final GrReferenceExpression ref = (GrReferenceExpression)configureByFile("genericWildcard/A.groovy").getElement();
     assertEquals("A<Base>", ref.getType().getCanonicalText());
   }
+
+  public void testArrayLikeAccessWithIntSequence() {
+    final GrReferenceExpression ref = (GrReferenceExpression)configureByFile("arrayLikeAccessWithIntSequence/A.groovy").getElement();
+    assertEquals("java.util.List", ref.getType().getCanonicalText());
+  }
 }

plugins/groovy/testdata/resolve/inference/arrayLikeAccessWithIntSequence/A.groovy

@@ -0,0 +1,4 @@
+def foo = [1, 2, 5]
+def list = foo[1, 2]
+
+print l<ref>ist