From d4c560f670fb0b4a091caa92d36c796ebd74f61a Mon Sep 17 00:00:00 2001
From: Bas Leijdekkers <basleijdekkers@gmail.com>
Date: Fri, 28 Sep 2018 17:13:44 +0200
Subject: [PATCH] IG: check if type is assignable (IDEA-199613)

---
 .../ConstantValueVariableUseInspection.java   | 31 ++++++++++++-------
 .../ConstantValueVariableUse.java             |  8 +++++
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/dataflow/ConstantValueVariableUseInspection.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/dataflow/ConstantValueVariableUseInspection.java
index 67d3a28b2cf4..ba19bf7d5397 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/dataflow/ConstantValueVariableUseInspection.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/dataflow/ConstantValueVariableUseInspection.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2008-2015 Bas Leijdekkers
+ * Copyright 2008-2018 Bas Leijdekkers
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -153,16 +153,16 @@ public class ConstantValueVariableUseInspection extends BaseInspection implement
       return false;
     }
 
-    private boolean checkConstantValueVariableUse(
-      @Nullable PsiExpression expression,
-      @NotNull PsiExpression constantExpression,
-      @NotNull PsiElement body) {
+    private boolean checkConstantValueVariableUse(@Nullable PsiExpression expression,
+                                                  @NotNull PsiExpression constantExpression,
+                                                  @NotNull PsiElement body) {
       final PsiType constantType = constantExpression.getType();
+      if (constantType == null) {
+        return false;
+      }
       if (PsiType.DOUBLE.equals(constantType)) {
-        final Object result = ExpressionUtils.computeConstantExpression(
-          constantExpression, false);
-        if (Double.valueOf(0.0).equals(result) ||
-            Double.valueOf(-0.0).equals(result)) {
+        final Object result = ExpressionUtils.computeConstantExpression(constantExpression, false);
+        if (Double.valueOf(0.0).equals(result) || Double.valueOf(-0.0).equals(result)) {
           return false;
         }
       }
@@ -170,8 +170,7 @@ public class ConstantValueVariableUseInspection extends BaseInspection implement
       if (!(expression instanceof PsiReferenceExpression)) {
         return false;
       }
-      final PsiReferenceExpression referenceExpression =
-        (PsiReferenceExpression)expression;
+      final PsiReferenceExpression referenceExpression = (PsiReferenceExpression)expression;
       final PsiElement target = referenceExpression.resolve();
       if (!(target instanceof PsiVariable)) {
         return false;
@@ -185,7 +184,15 @@ public class ConstantValueVariableUseInspection extends BaseInspection implement
       if (!visitor.isRead()) {
         return false;
       }
-      registerError(visitor.getReference(), constantExpression);
+      final PsiReferenceExpression reference = visitor.getReference();
+      final PsiType referenceType = reference.getType();
+      if (referenceType == null) {
+        return false;
+      }
+      if (!referenceType.isAssignableFrom(constantType)) {
+        return false;
+      }
+      registerError(reference, constantExpression);
       return true;
     }
   }
diff --git a/plugins/InspectionGadgets/test/com/siyeh/igtest/dataflow/constant_value_variable_use/ConstantValueVariableUse.java b/plugins/InspectionGadgets/test/com/siyeh/igtest/dataflow/constant_value_variable_use/ConstantValueVariableUse.java
index 756c0765a35d..120d5ae78e7f 100644
--- a/plugins/InspectionGadgets/test/com/siyeh/igtest/dataflow/constant_value_variable_use/ConstantValueVariableUse.java
+++ b/plugins/InspectionGadgets/test/com/siyeh/igtest/dataflow/constant_value_variable_use/ConstantValueVariableUse.java
@@ -58,4 +58,12 @@ class D  {
             }
         }
     }
+
+    private <T> T foo(Class<T> type) {
+        T result = null;
+        if (type == Boolean.class) {
+            result = type.cast( true);
+        }
+        return result;
+    }
 }
\ No newline at end of file