From fa99f2dd20c6258f6252ad000074946df73a9af9 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <tagir.valeev@jetbrains.com>
Date: Fri, 1 Dec 2023 17:16:59 +0100
Subject: [PATCH] [java-dfa] Do not rely on equivalence relation for floating
 point types

Fixes IDEA-339464 "Constant values" false positive for NaN

GitOrigin-RevId: a7b824f8d6ba0d6a8e4c9dd402ed6810a60e0066
---
 .../dataFlow/fixture/DoubleNaN2.java          | 19 +++++++++++++++++++
 .../DataFlowInspectionTest.java               |  1 +
 .../dataFlow/memory/DfaMemoryStateImpl.java   | 12 +++++++-----
 3 files changed, 27 insertions(+), 5 deletions(-)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/fixture/DoubleNaN2.java

diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/DoubleNaN2.java b/java/java-tests/testData/inspection/dataFlow/fixture/DoubleNaN2.java
new file mode 100644
index 000000000000..6b843ac287b4
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/DoubleNaN2.java
@@ -0,0 +1,19 @@
+public class DoubleNaN2 {
+  public static int compare(double lhs, double rhs) {
+    if (lhs == rhs) {
+      return 0;
+    }
+    if (lhs < rhs) {
+      return -1;
+    }
+
+    if (lhs > rhs) {
+      return 1;
+    }
+
+    if (Double.isNaN(lhs)) {
+      return Double.isNaN(rhs) ? 0 : -1;
+    }
+    return 1;
+  }
+}
\ 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 63c467bd774f..54c7a9edd52c 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspectionTest.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspectionTest.java
@@ -192,6 +192,7 @@ public class DataFlowInspectionTest extends DataFlowInspectionTestCase {
 
   public void testMethodCallFlushesField() { doTest(); }
   public void testDoubleNaN() { doTest(); }
+  public void testDoubleNaN2() { doTest(); }
   public void testUnknownFloatMayBeNaN() { doTest(); }
   public void testBoxedNaN() { doTest(); }
   public void testFloatEquality() { doTest(); }
diff --git a/platform/analysis-impl/src/com/intellij/codeInspection/dataFlow/memory/DfaMemoryStateImpl.java b/platform/analysis-impl/src/com/intellij/codeInspection/dataFlow/memory/DfaMemoryStateImpl.java
index 387c034ce34f..9aa1bb22f7da 100644
--- a/platform/analysis-impl/src/com/intellij/codeInspection/dataFlow/memory/DfaMemoryStateImpl.java
+++ b/platform/analysis-impl/src/com/intellij/codeInspection/dataFlow/memory/DfaMemoryStateImpl.java
@@ -1029,11 +1029,13 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
   }
 
   private boolean applyEquivalenceRelation(RelationType type, DfaValue dfaLeft, DfaValue dfaRight) {
-    RelationType currentRelation = getRelation(dfaLeft, dfaRight);
-    if (currentRelation != null) {
-      // Eq: NE & GE => GT
-      type = type.meet(currentRelation);
-      if (type == null) return false;
+    if (!dfaLeft.getDfType().hasNonStandardEquivalence() && !dfaRight.getDfType().hasNonStandardEquivalence()) {
+      RelationType currentRelation = getRelation(dfaLeft, dfaRight);
+      if (currentRelation != null) {
+        // Eq: NE & GE => GT
+        type = type.meet(currentRelation);
+        if (type == null) return false;
+      }
     }
     boolean isNegated = type == RelationType.NE || type == RelationType.GT || type == RelationType.LT;
     if (!isNegated && type != RelationType.EQ) {