Kotlin: Exclude constructs in serialization constructors from java/evaluation-to-constant

Author: tamasvajk

java/ql/lib/semmle/code/java/deadcode/DeadCode.qll

@@ -3,6 +3,7 @@ import semmle.code.java.deadcode.DeadEnumConstant
 import semmle.code.java.deadcode.DeadCodeCustomizations
 import semmle.code.java.deadcode.DeadField
 import semmle.code.java.deadcode.EntryPoints
+private import semmle.code.java.frameworks.kotlin.Serialization
 
 /**
  * Holds if the given callable has any liveness causes.
@@ -309,10 +310,7 @@ class RootdefCallable extends Callable {
     this.isCompilerGenerated()
     or
     // Exclude Kotlin serialization constructors.
-    this.(Constructor)
-        .getParameterType(this.getNumberOfParameters() - 1)
-        .(RefType)
-        .hasQualifiedName("kotlinx.serialization.internal", "SerializationConstructorMarker")
+    this instanceof SerializationConstructor
   }
 }
 

java/ql/lib/semmle/code/java/frameworks/kotlin/Serialization.qll

@@ -0,0 +1,16 @@
+/**
+ * Provides classes and predicates for working with thi `kotlinx.serialization` plugin.
+ */
+
+import java
+
+/**
+ * A constructor with a `SerializationConstructorMarker` parameter.
+ */
+class SerializationConstructor extends Constructor {
+  SerializationConstructor() {
+    this.getParameterType(this.getNumberOfParameters() - 1)
+        .(RefType)
+        .hasQualifiedName("kotlinx.serialization.internal", "SerializationConstructorMarker")
+  }
+}

java/ql/src/Likely Bugs/Arithmetic/ConstantExpAppearsNonConstant.ql

@@ -10,6 +10,7 @@
  */
 
 import java
+private import semmle.code.java.frameworks.kotlin.Serialization
 
 int eval(Expr e) { result = e.(CompileTimeConstantExpr).getIntValue() }
 
@@ -59,5 +60,7 @@ where
   // Exclude explicit zero multiplication.
   not e.(MulExpr).getAnOperand().(IntegerLiteral).getIntValue() = 0 and
   // Exclude expressions that appear to be disabled deliberately (e.g. `false && ...`).
-  not e.(AndLogicalExpr).getAnOperand().(BooleanLiteral).getBooleanValue() = false
+  not e.(AndLogicalExpr).getAnOperand().(BooleanLiteral).getBooleanValue() = false and
+  // Exclude expressions that are in serialization constructors, which are auto-generated.
+  not e.getEnclosingCallable() instanceof SerializationConstructor
 select e, "Expression always evaluates to the same value."