Improve IdentityConversion check (#407)

If the result of an explicit boxing operation is immediately dereferenced, then the explicit conversion operation is not redundant.
PicnicSupermarket · Dec 21, 2022 · 5665470 · 5665470
1 parent d0a89da
commit 5665470
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diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/IdentityConversion.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/IdentityConversion.java
@@ -23,6 +23,7 @@
 import com.google.errorprone.util.ASTHelpers;
 import com.google.errorprone.util.ASTHelpers.TargetType;
 import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MemberSelectTree;
 import com.sun.source.tree.MethodInvocationTree;
 import com.sun.tools.javac.code.Type;
 import com.sun.tools.javac.code.Types;
@@ -98,6 +99,15 @@ public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState
       return Description.NO_MATCH;
     }
 
+    if (sourceType.isPrimitive()
+        && state.getPath().getParentPath().getLeaf() instanceof MemberSelectTree) {
+      /*
+       * The result of the conversion method is dereferenced, while the source type is a primitive:
+       * dropping the conversion would yield uncompilable code.
+       */
+      return Description.NO_MATCH;
+    }
+
     return buildDescription(tree)
         .setMessage(
             "This method invocation appears redundant; remove it or suppress this warning and "

diff --git a/...rone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/IdentityConversionTest.java b/...rone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/IdentityConversionTest.java
@@ -118,6 +118,13 @@ void identification() {
             "    // BUG: Diagnostic contains:",
             "    short s4 = Short.valueOf(Short.MIN_VALUE);",
             "",
+            "    // BUG: Diagnostic contains:",
+            "    String boolStr = Boolean.valueOf(Boolean.FALSE).toString();",
+            "    int boolHash = Boolean.valueOf(false).hashCode();",
+            "    // BUG: Diagnostic contains:",
+            "    int byteHash = Byte.valueOf((Byte) Byte.MIN_VALUE).hashCode();",
+            "    String byteStr = Byte.valueOf(Byte.MIN_VALUE).toString();",
+            "",
             "    String str1 = String.valueOf(0);",
             "    // BUG: Diagnostic contains:",
             "    String str2 = String.valueOf(\"1\");",