From 9cdb5a70af6097c6b3af9ee0f931820e48b3ac60 Mon Sep 17 00:00:00 2001
From: "Anna.Kozlova" <anna.kozlova@jetbrains.com>
Date: Fri, 8 Apr 2016 18:23:26 +0200
Subject: [PATCH] trivial method ref: check if qualifier is of assignable type
 (IDEA-154422)

---
 .../TrivialMethodReferenceInspection.java     | 19 +++++++++++++------
 .../beforeOnUnassignable.java                 | 14 ++++++++++++++
 2 files changed, 27 insertions(+), 6 deletions(-)
 create mode 100644 java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/trivialMethodReference/beforeOnUnassignable.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/TrivialMethodReferenceInspection.java b/java/java-analysis-impl/src/com/intellij/codeInspection/TrivialMethodReferenceInspection.java
index b66674135de7..5978a899105b 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/TrivialMethodReferenceInspection.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/TrivialMethodReferenceInspection.java
@@ -19,6 +19,7 @@ import com.intellij.codeInsight.FileModificationService;
 import com.intellij.openapi.project.Project;
 import com.intellij.psi.*;
 import com.intellij.psi.util.MethodSignatureUtil;
+import com.intellij.psi.util.TypeConversionUtil;
 import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.NotNull;
 
@@ -32,12 +33,18 @@ public class TrivialMethodReferenceInspection extends BaseJavaBatchLocalInspecti
         final PsiExpression qualifierExpression = expression.getQualifierExpression();
         final PsiElement referenceNameElement = expression.getReferenceNameElement();
         if (qualifierExpression != null && referenceNameElement != null) {
-          final PsiMethod interfaceMethod = LambdaUtil.getFunctionalInterfaceMethod(expression);
-          if (interfaceMethod != null) {
-            final PsiElement resolve = expression.resolve();
-            if (resolve instanceof PsiMethod && 
-                (interfaceMethod == resolve || MethodSignatureUtil.isSuperMethod(interfaceMethod, (PsiMethod)resolve))) {
-              holder.registerProblem(referenceNameElement, "Method reference can be replaced with qualifier", new ReplaceMethodRefWithQualifierFix());
+          final PsiType qualifierType = qualifierExpression.getType();
+          if (qualifierType != null) {
+            final PsiType functionalInterfaceType = expression.getFunctionalInterfaceType();
+            final PsiMethod interfaceMethod = LambdaUtil.getFunctionalInterfaceMethod(functionalInterfaceType);
+            if (interfaceMethod != null) {
+              final PsiElement resolve = expression.resolve();
+              if (resolve instanceof PsiMethod &&
+                  (interfaceMethod == resolve || MethodSignatureUtil.isSuperMethod(interfaceMethod, (PsiMethod)resolve)) &&
+                  TypeConversionUtil.isAssignable(functionalInterfaceType, qualifierType)) {
+                holder.registerProblem(referenceNameElement, "Method reference can be replaced with qualifier",
+                                       new ReplaceMethodRefWithQualifierFix());
+              }
             }
           }
         }
diff --git a/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/trivialMethodReference/beforeOnUnassignable.java b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/trivialMethodReference/beforeOnUnassignable.java
new file mode 100644
index 000000000000..b69cd789483e
--- /dev/null
+++ b/java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/trivialMethodReference/beforeOnUnassignable.java
@@ -0,0 +1,14 @@
+// "Replace with qualifier" "false"
+class Test {
+  nterface A {
+    void m();
+  }
+
+  interface B extends A {}
+
+  void foo(B b) {}
+
+  void bar(A a){
+    foo(a::<caret>m);
+  }
+}
\ No newline at end of file