From 985b752fadafd385e668ddb800721b325284f520 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Tue, 12 May 2020 11:17:49 +0700
Subject: [PATCH] Avoid inlining lambdas not from local scope

When lambda is defined in the outer scope a number of problems may appear during the analysis. First, it actually could be analyzed twice producing different warnings (in inlining context, and as standalone expression). Second, trap-handling assumes that all exited expressions should appear within the current codeFragment. This could be violated when lambda comes from the outer scope, resulting in incorrect jumps.

Fixes IDEA-240328 Condition always false inspection is wrong if using switch expressions

GitOrigin-RevId: 11794502d2e661044fa2105402955aa54e3c1245
---
 .../codeInspection/dataFlow/CFGBuilder.java   | 21 ++++++++++++-------
 .../SwitchExpressionAndLambdaInlining.java    | 11 ++++++++++
 .../DataFlowInspection14Test.java             |  1 +
 3 files changed, 25 insertions(+), 8 deletions(-)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/fixture/SwitchExpressionAndLambdaInlining.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CFGBuilder.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CFGBuilder.java
index 0c9030d2237f..9b26a6b7d264 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CFGBuilder.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/CFGBuilder.java
@@ -26,6 +26,7 @@ import com.intellij.codeInspection.dataFlow.value.DfaValueFactory;
 import com.intellij.codeInspection.dataFlow.value.DfaVariableValue;
 import com.intellij.psi.*;
 import com.intellij.psi.tree.IElementType;
+import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.ObjectUtils;
 import com.intellij.util.containers.ContainerUtil;
@@ -766,14 +767,18 @@ public class CFGBuilder {
     }
     PsiLocalVariable localFn = ExpressionUtils.resolveLocalVariable(stripped);
     if (localFn != null) {
-      PsiLambdaExpression localLambda =
-        ObjectUtils.tryCast(PsiUtil.skipParenthesizedExprDown(localFn.getInitializer()), PsiLambdaExpression.class);
-      if (myAnalyzer.wasAdded(localLambda)) {
-        PsiElement scope = PsiUtil.getVariableCodeBlock(localFn, null);
-        List<PsiReferenceExpression> refs = VariableAccessUtils.getVariableReferences(localFn, scope);
-        if (ContainerUtil.getOnlyItem(refs) == stripped) {
-          myAnalyzer.removeLambda(localLambda);
-          return tryInlineLambda(argCount, localLambda, resultNullability, pushArgs);
+      PsiElement parent =
+        PsiTreeUtil.getParentOfType(functionalExpression, PsiLambdaExpression.class, PsiClass.class, PsiMethod.class);
+      if (PsiTreeUtil.isAncestor(parent, localFn, true)) {
+        PsiLambdaExpression localLambda =
+          ObjectUtils.tryCast(PsiUtil.skipParenthesizedExprDown(localFn.getInitializer()), PsiLambdaExpression.class);
+        if (myAnalyzer.wasAdded(localLambda)) {
+          PsiElement scope = PsiUtil.getVariableCodeBlock(localFn, null);
+          List<PsiReferenceExpression> refs = VariableAccessUtils.getVariableReferences(localFn, scope);
+          if (ContainerUtil.getOnlyItem(refs) == stripped) {
+            myAnalyzer.removeLambda(localLambda);
+            return tryInlineLambda(argCount, localLambda, resultNullability, pushArgs);
+          }
         }
       }
     }
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/SwitchExpressionAndLambdaInlining.java b/java/java-tests/testData/inspection/dataFlow/fixture/SwitchExpressionAndLambdaInlining.java
new file mode 100644
index 000000000000..cff2b4e04aea
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/SwitchExpressionAndLambdaInlining.java
@@ -0,0 +1,11 @@
+import java.util.function.Predicate;
+
+class SwitchExpr {
+  void test() {
+    Predicate<String> predicate = value -> switch(value) {
+      case "A" -> true;
+      default -> false;
+    };
+    Predicate<String> otherPredicate = value -> value.length() == 1 && predicate.test(value);
+  }
+}
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection14Test.java b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection14Test.java
index 5047fdf64a38..626f3cff4e64 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection14Test.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection14Test.java
@@ -25,4 +25,5 @@ public class DataFlowInspection14Test extends DataFlowInspectionTestCase {
     myFixture.addClass("package java.lang.constant; public interface ConstantDesc {}");
     doTest();
   }
+  public void testSwitchExpressionAndLambdaInlining() { doTest(); }
 }
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