method ref: inline method ref in qualifier place; do not treat cast as redundant there

java/java-impl/src/com/intellij/refactoring/util/InlineUtil.java

@@ -137,17 +137,9 @@ public class InlineUtil {
         }
       }
     } else if (exprType instanceof PsiLambdaExpressionType) {
-      final PsiLambdaExpression expression = ((PsiLambdaExpressionType)exprType).getExpression();
-      if (expression.getParent() instanceof PsiReferenceExpression) {
-        PsiTypeCastExpression cast = (PsiTypeCastExpression)JavaPsiFacade.getElementFactory(expr.getProject()).createExpressionFromText("(t)a", null);
-        PsiTypeElement castTypeElement = cast.getCastType();
-        assert castTypeElement != null;
-        castTypeElement.replace(variable.getTypeElement());
-        final PsiExpression operand = cast.getOperand();
-        assert operand != null;
-        operand.replace(expr);
-        expr = (PsiTypeCastExpression)expr.replace(cast);
-      }
+      expr = surroundWithCast(variable, expr, ((PsiLambdaExpressionType)exprType).getExpression());
+    } else if (exprType instanceof PsiMethodReferenceType) {
+      expr = surroundWithCast(variable, expr, ((PsiMethodReferenceType)exprType).getExpression());
     }
 
     ChangeContextUtil.clearContextInfo(initializer);
@@ -157,6 +149,20 @@ public class InlineUtil {
     return (PsiExpression)ChangeContextUtil.decodeContextInfo(expr, thisClass, thisAccessExpr);
   }
 
+  private static PsiExpression surroundWithCast(PsiVariable variable, PsiExpression expr, PsiExpression expression) {
+    if (expression.getParent() instanceof PsiReferenceExpression) {
+      PsiTypeCastExpression cast = (PsiTypeCastExpression)JavaPsiFacade.getElementFactory(expr.getProject()).createExpressionFromText("(t)a", null);
+      PsiTypeElement castTypeElement = cast.getCastType();
+      assert castTypeElement != null;
+      castTypeElement.replace(variable.getTypeElement());
+      final PsiExpression operand = cast.getOperand();
+      assert operand != null;
+      operand.replace(expr);
+      expr = (PsiTypeCastExpression)expr.replace(cast);
+    }
+    return expr;
+  }
+
   private static PsiThisExpression createThisExpression(PsiManager manager, PsiClass thisClass, PsiClass refParent) {
     PsiThisExpression thisAccessExpr = null;
     if (Comparing.equal(thisClass, refParent))

java/java-psi-api/src/com/intellij/psi/PsiMethodReferenceType.java

@@ -70,4 +70,8 @@ public class PsiMethodReferenceType extends PsiType {
   public PsiType[] getSuperTypes() {
     return PsiType.EMPTY_ARRAY;
   }
+
+  public PsiMethodReferenceExpression getExpression() {
+    return myReference;
+  }
 }

java/java-tests/testData/inspection/redundantCast/lambda/MethodRefContext/expected.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems/>

java/java-tests/testData/inspection/redundantCast/lambda/MethodRefContext/src/Test.java

@@ -0,0 +1,13 @@
+class Test {
+  {
+      ((Bar) Test::length)._("");
+  }
+
+  public static Integer length(String s) {
+    return s.length();
+  }
+
+  interface Bar {
+    Integer _(String s);
+  }
+}

java/java-tests/testData/refactoring/inlineLocal/MethodRefAsRefQualifier.java

@@ -0,0 +1,14 @@
+class Test {
+  {
+      Bar bar = Test::length;
+      b<caret>ar._("");
+  }
+
+  public static Integer length(String s) {
+    return s.length();
+  }
+
+  interface Bar {
+    Integer _(String s);
+  }
+}

java/java-tests/testData/refactoring/inlineLocal/MethodRefAsRefQualifier.java.after

@@ -0,0 +1,13 @@
+class Test {
+  {
+      ((Bar) Test::length)._("");
+  }
+
+  public static Integer length(String s) {
+    return s.length();
+  }
+
+  interface Bar {
+    Integer _(String s);
+  }
+}

java/java-tests/testSrc/com/intellij/codeInspection/RedundantCast18Test.java

@@ -17,9 +17,6 @@ package com.intellij.codeInspection;
 
 import com.intellij.codeInspection.ex.LocalInspectionToolWrapper;
 import com.intellij.codeInspection.redundantCast.RedundantCastInspection;
-import com.intellij.openapi.projectRoots.JavaSdkVersion;
-import com.intellij.openapi.projectRoots.JavaVersionService;
-import com.intellij.openapi.projectRoots.JavaVersionServiceImpl;
 import com.intellij.openapi.projectRoots.Sdk;
 import com.intellij.openapi.projectRoots.impl.JavaSdkImpl;
 import com.intellij.openapi.roots.LanguageLevelProjectExtension;
@@ -33,6 +30,7 @@ public class RedundantCast18Test extends InspectionTestCase {
   }
 
   public void testLambdaContext() throws Exception { doTest(); }
+  public void testMethodRefContext() throws Exception { doTest(); }
   public void testExpectedSupertype() throws Exception { doTest(); }
 
   protected Sdk getTestProjectSdk() {

java/java-tests/testSrc/com/intellij/refactoring/inline/InlineLocalTest.java

@@ -168,6 +168,10 @@ public class InlineLocalTest extends LightCodeInsightTestCase {
     doTest(true);
   }
 
+  public void testMethodRefAsRefQualifier() throws Exception {
+    doTest(true);
+  }
+
   public void testLocalVarInsideLambdaBody() throws Exception {
     doTest(true);
   }

java/openapi/src/com/intellij/psi/util/RedundantCastUtil.java

@@ -389,7 +389,7 @@ public class RedundantCastUtil {
           }
         } else if (parent instanceof PsiSynchronizedStatement && (expr instanceof PsiExpression && ((PsiExpression)expr).getType() instanceof PsiPrimitiveType)) {
           return;
-        } else if (expr instanceof PsiLambdaExpression) {
+        } else if (expr instanceof PsiLambdaExpression || expr instanceof PsiMethodReferenceExpression) {
           if (parent instanceof PsiParenthesizedExpression && parent.getParent() instanceof PsiReferenceExpression) {
             return;
           }