Replace Map and similar functions with their Java cousins

smowton · smowton · commit ce87a89009b1 · 2022-05-12T22:36:28.000+01:00
This didn't appear to be necessary because the Kotlin and Java versions of Map (for example) are designed to be compatible, but in certain cases their functions have the same erasure but not the same type (e.g. Map.getOrDefault(K, V) vs. Map.getOrDefault(Object, V).

These have different erasures which was leading to callable-binding inconsistencies.
diff --git a/java/kotlin-extractor/src/main/kotlin/KotlinUsesExtractor.kt b/java/kotlin-extractor/src/main/kotlin/KotlinUsesExtractor.kt
@@ -899,17 +899,36 @@ open class KotlinUsesExtractor(
         return id
     }
 
+    fun kotlinFunctionToJavaEquivalent(f: IrFunction) =
+        f.parent.let {
+            when (it) {
+                is IrClass ->
+                    getJavaEquivalentClass(it)?.let { javaClass ->
+                        if (javaClass != it)
+                            javaClass.declarations.find { decl ->
+                                decl is IrFunction && decl.name == f.name && decl.valueParameters.size == f.valueParameters.size
+                            } as IrFunction
+                        else
+                            null
+                    }
+                else -> null
+            } ?: f
+        }
+
     fun <T: DbCallable> useFunction(f: IrFunction, classTypeArgsIncludingOuterClasses: List<IrTypeArgument>? = null): Label<out T> {
         if (f.isLocalFunction()) {
             val ids = getLocallyVisibleFunctionLabels(f)
             return ids.function.cast<T>()
         } else {
-            return useFunctionCommon<T>(f, getFunctionLabel(f, classTypeArgsIncludingOuterClasses))
+            val realFunction = kotlinFunctionToJavaEquivalent(f)
+            return useFunctionCommon<T>(realFunction, getFunctionLabel(realFunction, classTypeArgsIncludingOuterClasses))
         }
     }
 
     fun <T: DbCallable> useFunction(f: IrFunction, parentId: Label<out DbElement>, classTypeArgsIncludingOuterClasses: List<IrTypeArgument>?) =
-        useFunctionCommon<T>(f, getFunctionLabel(f, parentId, classTypeArgsIncludingOuterClasses))
+        kotlinFunctionToJavaEquivalent(f).let {
+            useFunctionCommon<T>(it, getFunctionLabel(it, parentId, classTypeArgsIncludingOuterClasses))
+        }
 
     fun getTypeArgumentLabel(
         arg: IrTypeArgument
diff --git a/java/ql/test/kotlin/library-tests/java-map-methods/test.kt b/java/ql/test/kotlin/library-tests/java-map-methods/test.kt
@@ -0,0 +1 @@
+fun test(m: Map<Int, Int>) = m.getOrDefault(1, 2)
diff --git a/java/ql/test/kotlin/library-tests/java-map-methods/test.ql b/java/ql/test/kotlin/library-tests/java-map-methods/test.ql
@@ -0,0 +1,4 @@
+import java
+
+from MethodAccess ma
+select ma.getCallee().getAParameter().getType().toString()

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+fun test(m: Map<Int, Int>) = m.getOrDefault(1, 2)`