IDEA-91483 infer type of closure parameter if closure is casted to interface

plugins/groovy/src/META-INF/plugin.xml

@@ -127,6 +127,7 @@
     <psiEnhancerCategory implementation="org.jetbrains.plugins.groovy.dsl.psi.PsiExpressionCategory"/>
 
     <variableEnhancer implementation="org.jetbrains.plugins.groovy.lang.psi.typeEnhancers.ClosureParameterEnhancer"/>
+    <variableEnhancer implementation="org.jetbrains.plugins.groovy.lang.psi.typeEnhancers.ClosureAsAnonymousParameterEnhancer"/>
 
     <membersContributor implementation="org.jetbrains.plugins.groovy.gant.GantMemberContributor"/>
 

plugins/groovy/src/org/jetbrains/plugins/groovy/gpp/GppClosureParameterTypeProvider.java

@@ -114,7 +114,7 @@ public class GppClosureParameterTypeProvider extends AbstractClosureParameterEnh
   }
 
   @Nullable
-  private static PsiType getSingleMethodParameterType(@Nullable PsiType type, int index, GrClosableBlock closure) {
+  public static PsiType getSingleMethodParameterType(@Nullable PsiType type, int index, GrClosableBlock closure) {
     final PsiType[] signature = findSingleAbstractMethodSignature(type);
     if (signature != null && GrClosureSignatureUtil.isSignatureApplicable(GrClosureSignatureUtil.createSignature(closure), signature, closure)) {
       return signature.length > index ?  signature[index] : PsiType.NULL;

plugins/groovy/src/org/jetbrains/plugins/groovy/gpp/GppTypeConverter.java

@@ -76,7 +76,7 @@ public class GppTypeConverter extends GrTypeConverter {
         return true;
       }
     }
-    else if (rType instanceof GrClosureType) {
+    else if (rType instanceof GrClosureType && hasTypedContext(context)) {
       final PsiType[] methodParameters = GppClosureParameterTypeProvider.findSingleAbstractMethodSignature(lType);
       if (isClosureOverride(methodParameters, (GrClosureType)rType, context)) return true;
     }

plugins/groovy/src/org/jetbrains/plugins/groovy/lang/psi/typeEnhancers/ClosureAsAnonymousParameterEnhancer.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2000-2012 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.
+ */
+package org.jetbrains.plugins.groovy.lang.psi.typeEnhancers;
+
+import com.intellij.psi.PsiManager;
+import com.intellij.psi.PsiType;
+import com.intellij.psi.search.GlobalSearchScope;
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.plugins.groovy.gpp.GppClosureParameterTypeProvider;
+import org.jetbrains.plugins.groovy.lang.psi.api.statements.blocks.GrClosableBlock;
+import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrSafeCastExpression;
+import org.jetbrains.plugins.groovy.lang.psi.api.types.GrTypeElement;
+import org.jetbrains.plugins.groovy.lang.psi.expectedTypes.GroovyExpectedTypesProvider;
+import org.jetbrains.plugins.groovy.lang.psi.impl.statements.expressions.TypesUtil;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * @author Max Medvedev
+ */
+public class ClosureAsAnonymousParameterEnhancer extends AbstractClosureParameterEnhancer {
+  @Nullable
+  @Override
+  protected PsiType getClosureParameterType(GrClosableBlock closure, int index) {
+
+    Set<PsiType> expectedTypes;
+
+    if (closure.getParent() instanceof GrSafeCastExpression) {
+      GrSafeCastExpression safeCastExpression = (GrSafeCastExpression)closure.getParent();
+      GrTypeElement typeElement = safeCastExpression.getCastTypeElement();
+      if (typeElement != null) {
+        PsiType castType = typeElement.getType();
+        expectedTypes = new HashSet<PsiType>(GroovyExpectedTypesProvider.getDefaultExpectedTypes(safeCastExpression));
+        PsiManager manager = closure.getManager();
+        GlobalSearchScope scope = closure.getResolveScope();
+        for (PsiType expected : expectedTypes) {
+          if (!TypesUtil.isAssignable(expected, castType, manager, scope)) {
+            expectedTypes.remove(expected);
+          }
+        }
+
+        if (expectedTypes.isEmpty()) expectedTypes.add(castType);
+      }
+      else {
+        expectedTypes = GroovyExpectedTypesProvider.getDefaultExpectedTypes(closure);
+      }
+    }
+    else {
+      expectedTypes = GroovyExpectedTypesProvider.getDefaultExpectedTypes(closure);
+    }
+
+    for (PsiType constraint : expectedTypes) {
+      final PsiType suggestion = GppClosureParameterTypeProvider.getSingleMethodParameterType(constraint, index, closure);
+      if (suggestion != null) {
+        return suggestion;
+      }
+    }
+
+    return null;
+  }
+}

plugins/groovy/test/org/jetbrains/plugins/groovy/lang/GroovyHighlightingTest.groovy

@@ -1452,6 +1452,25 @@ List<String> foo() {[]}
 def (int <warning descr="Cannot assign 'String' to 'int'">x</warning>, String y) = foo()
 
 List<String> foo() {[]}
+''', GroovyAssignabilityCheckInspection)
+  }
+
+  void testCastClosureToInterface() {
+    testHighlighting('''\
+interface Function<D, F> {
+    F fun(D d)
+}
+
+def foo(Function<String, String> function) {
+ //   print function.fun('abc')
+}
+
+
+foo<warning descr="'foo' in '_' cannot be applied to '(Function<java.lang.Double,java.lang.Double>)'">({println  it.byteValue()} as Function<Double, Double>)</warning>
+foo({println  it.substring(1)} as Function)
+foo({println  it.substring(1)} as Function<String, String>)
+foo<warning descr="'foo' in '_' cannot be applied to '(groovy.lang.Closure<java.lang.Void>)'">({println  it})</warning>
+
 ''', GroovyAssignabilityCheckInspection)
   }