From 1056b3a3298d40b1d4d1abdc962362644a11d52d Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Fri, 9 Nov 2018 15:31:53 +0700
Subject: [PATCH] SimplifyOptionalCallChainsInspection: specify lambda
 parameter types when converting method reference to lambda

Fixes IDEA-201902 Simplify optional chain (use Optional.stream())
---
 .../SimplifyOptionalCallChainsInspection.java          | 10 ++++++----
 .../inspection/optionalChains/afterStreamJava9.java    |  6 ++++--
 .../inspection/optionalChains/beforeStreamJava9.java   |  4 +++-
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/java/java-impl/src/com/intellij/codeInspection/SimplifyOptionalCallChainsInspection.java b/java/java-impl/src/com/intellij/codeInspection/SimplifyOptionalCallChainsInspection.java
index 3e3d7713e87d..1518bdb863e6 100644
--- a/java/java-impl/src/com/intellij/codeInspection/SimplifyOptionalCallChainsInspection.java
+++ b/java/java-impl/src/com/intellij/codeInspection/SimplifyOptionalCallChainsInspection.java
@@ -4,7 +4,6 @@ package com.intellij.codeInspection;
 import com.intellij.codeInspection.dataFlow.CommonDataflow;
 import com.intellij.codeInspection.dataFlow.DfaFactType;
 import com.intellij.codeInspection.util.LambdaGenerationUtil;
-import com.intellij.codeInspection.util.OptionalUtil;
 import com.intellij.openapi.project.Project;
 import com.intellij.pom.java.LanguageLevel;
 import com.intellij.psi.*;
@@ -151,7 +150,7 @@ public class SimplifyOptionalCallChainsInspection extends AbstractBaseJavaLocalI
       if (qualifier == null) return;
       String opt = qualifier.getText();
       PsiParameter parameter = parameters[0];
-      String proposed = OptionalUtil.generateOptionalUnwrap(opt, parameter, trueArg, falseArg, call.getType(), useOrElseGet);
+      String proposed = generateOptionalUnwrap(opt, parameter, trueArg, falseArg, call.getType(), useOrElseGet);
       String canonicalOrElse;
       if (useOrElseGet && !ExpressionUtils.isSafelyRecomputableExpression(falseArg)) {
         canonicalOrElse = ".orElseGet(() -> " + falseArg.getText() + ")";
@@ -167,7 +166,7 @@ public class SimplifyOptionalCallChainsInspection extends AbstractBaseJavaLocalI
         } else if(opt.length() > 10) {
           // should be a parseable expression
           opt = "(($))";
-          String template = OptionalUtil.generateOptionalUnwrap(opt, parameter, trueArg, falseArg, call.getType(), useOrElseGet);
+          String template = generateOptionalUnwrap(opt, parameter, trueArg, falseArg, call.getType(), useOrElseGet);
           displayCode =
             PsiExpressionTrimRenderer.render(JavaPsiFacade.getElementFactory(parameter.getProject()).createExpressionFromText(template, call));
           displayCode = displayCode.replaceFirst(Pattern.quote(opt), "..");
@@ -206,7 +205,10 @@ public class SimplifyOptionalCallChainsInspection extends AbstractBaseJavaLocalI
       return (PsiLambdaExpression)expression;
     }
     if (expression instanceof PsiMethodReferenceExpression) {
-      return LambdaRefactoringUtil.createLambda((PsiMethodReferenceExpression)expression, true);
+      PsiMethodReferenceExpression methodRef = (PsiMethodReferenceExpression)expression;
+      PsiLambdaExpression lambda = LambdaRefactoringUtil.createLambda(methodRef, true);
+      LambdaRefactoringUtil.specifyLambdaParameterTypes(methodRef.getFunctionalInterfaceType(), lambda);
+      return lambda;
     }
     return null;
   }
diff --git a/java/java-tests/testData/inspection/optionalChains/afterStreamJava9.java b/java/java-tests/testData/inspection/optionalChains/afterStreamJava9.java
index 262a2dc78e5b..fc61ac021f16 100644
--- a/java/java-tests/testData/inspection/optionalChains/afterStreamJava9.java
+++ b/java/java-tests/testData/inspection/optionalChains/afterStreamJava9.java
@@ -8,12 +8,14 @@ public final class MyClass {
     Optional<String> name();
   }
 
-  public static void testStream(Person p) {
-    p.name().stream().flatMap(Stream::of).forEach(System.out::println);
+  public static void testStream(Person p, Optional<Integer> opt) {
+    p.name().stream().forEach(System.out::println);
     p.name().stream().map(String::trim).forEach(System.out::println);
     p.name().stream().flatMap(n -> Stream.of(n.split(""))).forEach(System.out::println);
     p.name().stream().mapToInt(String::length).forEach(System.out::println);
     p.name().stream().flatMapToInt(String::chars).forEach(System.out::println);
     p.name().filter(n -> !n.isEmpty()).stream().forEach(System.out::println);
+
+    Stream<Integer> stream = opt.stream();
   }
 }
\ No newline at end of file
diff --git a/java/java-tests/testData/inspection/optionalChains/beforeStreamJava9.java b/java/java-tests/testData/inspection/optionalChains/beforeStreamJava9.java
index 7f7327b7a918..c989c77ff3ca 100644
--- a/java/java-tests/testData/inspection/optionalChains/beforeStreamJava9.java
+++ b/java/java-tests/testData/inspection/optionalChains/beforeStreamJava9.java
@@ -8,12 +8,14 @@ public final class MyClass {
     Optional<String> name();
   }
 
-  public static void testStream(Person p) {
+  public static void testStream(Person p, Optional<Integer> opt) {
     p.name().map(Stream::of).or<caret>Else(Stream.empty()).forEach(System.out::println);
     p.name().map(n -> Stream.of(n.trim())).orElseGet(() -> Stream.empty()).forEach(System.out::println);
     p.name().map(n -> Stream.of(n.split(""))).orElse(Stream.empty()).forEach(System.out::println);
     p.name().map(n -> IntStream.of(n.length())).orElseGet(IntStream::empty).forEach(System.out::println);
     p.name().map(String::chars).orElseGet(IntStream::empty).forEach(System.out::println);
     p.name().map(n -> n.isEmpty() ? Stream.empty() : Stream.of(n)).orElseGet(Stream::empty).forEach(System.out::println);
+
+    Stream<Integer> stream = opt.map(Stream::of).orElseGet(Stream::empty);
   }
 }
\ No newline at end of file