redundant throws: find throws clauses inside functional expressions (IDEA-135181)

java/java-analysis-impl/src/com/intellij/codeInspection/reference/RefJavaUtilImpl.java

@@ -20,6 +20,7 @@
  */
 package com.intellij.codeInspection.reference;
 
+import com.intellij.codeInsight.ExceptionUtil;
 import com.intellij.codeInspection.InspectionsBundle;
 import com.intellij.psi.*;
 import com.intellij.psi.search.GlobalSearchScope;
@@ -30,6 +31,9 @@ import com.intellij.util.VisibilityUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Collection;
+import java.util.Collections;
+
 public class RefJavaUtilImpl extends RefJavaUtil{
 
   @Override
@@ -114,6 +118,29 @@ public class RefJavaUtilImpl extends RefJavaUtil{
             final PsiMethod interfaceMethod = LambdaUtil.getFunctionalInterfaceMethod(aClass);
             if (interfaceMethod != null) {
               refFrom.addReference(refFrom.getRefManager().getReference(interfaceMethod), interfaceMethod, psiFrom, false, true, null);
+
+              PsiElement body = null;
+              PsiElement topElement = null;
+              if (expression instanceof PsiLambdaExpression) {
+                body = ((PsiLambdaExpression)expression).getBody();
+                topElement = expression;
+              }
+              else {
+                final PsiElement resolve = ((PsiMethodReferenceExpression)expression).resolve();
+                if (resolve instanceof PsiMethod) {
+                  body = ((PsiMethod)resolve).getBody();
+                  topElement = resolve;
+                }
+              }
+
+              final Collection<PsiClassType> exceptionTypes = body != null ? ExceptionUtil.collectUnhandledExceptions(body, topElement, false) 
+                                                                           : Collections.<PsiClassType>emptyList();
+              RefElement refResolved = refFrom.getRefManager().getReference(interfaceMethod);
+              if (refResolved instanceof RefMethodImpl) {
+                for (final PsiClassType exceptionType : exceptionTypes) {
+                  ((RefMethodImpl)refResolved).updateThrowsList(exceptionType);
+                }
+              }
             }
           }
         }

java/java-tests/testData/inspection/redundantThrow/ThrownClausesInFunctionalExpressions/expected.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems>
+  <problem>
+    <file>Foo.java</file>
+    <line>21</line>
+    <description>ObjectStreamException</description>
+  </problem>
+</problems>
+

java/java-tests/testData/inspection/redundantThrow/ThrownClausesInFunctionalExpressions/src/Foo.java

@@ -0,0 +1,23 @@
+import java.io.*;
+
+class ExceptionTest {
+
+  MyFunction method() {
+    return () -> {
+      throw new EOFException();
+    };
+  }
+
+  MyFunction method1() {
+    return this::e;
+  }
+
+  private void e() throws FileNotFoundException {
+    throw new FileNotFoundException();
+  }
+
+  @FunctionalInterface
+  private interface MyFunction {
+    void call() throws FileNotFoundException, EOFException, ObjectStreamException;
+  }
+}

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

@@ -17,6 +17,10 @@ package com.intellij.codeInspection;
 
 import com.intellij.JavaTestUtil;
 import com.intellij.codeInspection.unneededThrows.RedundantThrows;
+import com.intellij.openapi.projectRoots.Sdk;
+import com.intellij.openapi.roots.LanguageLevelProjectExtension;
+import com.intellij.pom.java.LanguageLevel;
+import com.intellij.testFramework.IdeaTestUtil;
 import com.intellij.testFramework.InspectionTestCase;
 
 public class RedundantThrowTest extends InspectionTestCase {
@@ -60,4 +64,15 @@ public class RedundantThrowTest extends InspectionTestCase {
   public void testSelfCall() throws Exception {
     doTest();
   }
+
+  public void testThrownClausesInFunctionalExpressions() throws Exception {
+    doTest();
+  }
+
+  @Override
+  protected Sdk getTestProjectSdk() {
+    Sdk sdk = IdeaTestUtil.getMockJdk17();
+    LanguageLevelProjectExtension.getInstance(getProject()).setLanguageLevel(LanguageLevel.JDK_1_8);
+    return sdk;
+  }
 }