From 32f3fccaf7bbe3c984cd05b53db4212b6f50a0e6 Mon Sep 17 00:00:00 2001
From: Bas Leijdekkers <basleijdekkers@gmail.com>
Date: Thu, 13 Dec 2018 14:32:17 +0100
Subject: [PATCH] IG: don't suggest to replace if with switch on non-constant
 (IDEA-204135)

---
 .../com/siyeh/ig/psiutils/SwitchUtils.java    | 10 +++++++-
 .../migration/if_switch/IfCanBeSwitch.java    | 24 +++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/SwitchUtils.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/SwitchUtils.java
index d268d54fa72a..e5498ced7aed 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/SwitchUtils.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/SwitchUtils.java
@@ -230,7 +230,15 @@ public class SwitchUtils {
     }
     final PsiExpression left = check.getLeft();
     final PsiExpression right = check.getRight();
-    return PsiUtil.isConstantExpression(left) ? right : left;
+    if (PsiUtil.isConstantExpression(left)) {
+      return right;
+    }
+    else if (PsiUtil.isConstantExpression(right)) {
+      return left;
+    }
+    else {
+      return null;
+    }
   }
 
   private static boolean canBeCaseLabel(PsiExpression expression, LanguageLevel languageLevel) {
diff --git a/plugins/InspectionGadgets/test/com/siyeh/igtest/migration/if_switch/IfCanBeSwitch.java b/plugins/InspectionGadgets/test/com/siyeh/igtest/migration/if_switch/IfCanBeSwitch.java
index e189a0327cb6..5ccb5a98d493 100644
--- a/plugins/InspectionGadgets/test/com/siyeh/igtest/migration/if_switch/IfCanBeSwitch.java
+++ b/plugins/InspectionGadgets/test/com/siyeh/igtest/migration/if_switch/IfCanBeSwitch.java
@@ -92,4 +92,28 @@ class IfCanBeSwitch {
       System.out.println("-");
     }
   }
+}
+class MyText implements Comparable<MyText> {
+
+  private String name;
+
+  String getSuperType() {
+    return name.startsWith("a") ? "b" : "c";
+  }
+
+  @Override
+  public int compareTo(MyText o) {
+    String superType = getSuperType();
+    if (superType.equals(o.getSuperType())) {
+      return this.name.compareTo(o.name);
+    } else if (superType.equals("a")) {
+      return -1;
+    } else if (superType.equals("b")) {
+      return 1;
+    } else if (superType.equals("c")) {
+      return o.getSuperType().equals("a") ? 1 : -1;
+    } else {
+      return 0;
+    }
+  }
 }
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