From 8466dca99392dcfacaa2a39b3910a72891c8875a Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Thu, 25 Mar 2021 11:47:16 +0700
Subject: [PATCH] [java-dfa] containsConstant should ignore locality if values
 are compared by equals

Fixes IDEA-265089 ConstantCondition always false incorrectly reported on String.equals with String literal on left side

GitOrigin-RevId: 4e128a8308a9813bba953e107400c51879a6e7f2
---
 .../dataFlow/types/DfReferenceType.java        |  6 +++++-
 .../StringEqualityNewStringInMethod.java       | 18 ++++++++++++++++++
 .../codeInspection/DataFlowInspectionTest.java |  1 +
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/fixture/StringEqualityNewStringInMethod.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/types/DfReferenceType.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/types/DfReferenceType.java
index 44f1d13e934c..97750b0da05d 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/types/DfReferenceType.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/types/DfReferenceType.java
@@ -125,7 +125,11 @@ public interface DfReferenceType extends DfType {
 
   @Override
   default boolean containsConstant(@NotNull DfConstantType<?> constant) {
-    return dropTypeConstraint().isSuperType(constant);
+    DfReferenceType filtered = dropTypeConstraint();
+    if (getConstraint().isComparedByEquals()) {
+      filtered = filtered.dropLocality();
+    }
+    return filtered.isSuperType(constant);
   }
 
   @Override
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/StringEqualityNewStringInMethod.java b/java/java-tests/testData/inspection/dataFlow/fixture/StringEqualityNewStringInMethod.java
new file mode 100644
index 000000000000..6be634a5565f
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/StringEqualityNewStringInMethod.java
@@ -0,0 +1,18 @@
+public class StringEqualityNewStringInMethod {
+  // IDEA-265089
+  public boolean bad() {
+    return "baah".equals(toString("baah".getBytes("UTF-8")));
+  }
+
+  public boolean good() {
+    return "baah".equals(new String("baah".getBytes("UTF-8"), 0, 4, "UTF-8"));
+  }
+
+  public boolean good2() {
+    return toString("baah".getBytes("UTF-8")).equals("baah");
+  }
+
+  private static String toString(final byte[] data) {
+    return new String(data, 0, 4, "UTF-8");
+  }
+}
\ No newline at end of file
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspectionTest.java b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspectionTest.java
index d89e591109eb..10fb1cf899ea 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspectionTest.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspectionTest.java
@@ -622,6 +622,7 @@ public class DataFlowInspectionTest extends DataFlowInspectionTestCase {
   public void testVoidIsAlwaysNull() { doTest(); }
   public void testImpossibleType() { doTest(); }
   public void testStringEquality() { doTest(); }
+  public void testStringEqualityNewStringInMethod() { doTest(); }
   public void testAssignmentFieldAliasing() { doTest(); }
   public void testNewBoxedNumberEquality() { doTest(); }
   public void testBoxingIncorrectLiteral() { doTest(); }