Resolving unary operators

binary operator also works now

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/ScopeManager.kt

@@ -1203,7 +1203,10 @@ fun FunctionDeclaration.matchesSignature(
  * of the call resolution.
  */
 data class CallResolutionResult(
-    /** The original call expression or a node that implements [HasCallableArguments]. */
+    /**
+     * The original call expression or something that implements [HasCallableArguments] (e.g. an
+     * overloaded operator expression).
+     */
     val call: HasCallableArguments,
 
     /**

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/ExpressionBuilder.kt

@@ -280,6 +280,28 @@ fun MetadataProvider.newCallExpression(
     return node
 }
 
+/**
+ * Creates a new [MemberCallExpression]. The [MetadataProvider] receiver will be used to fill
+ * different meta-data using [Node.applyMetadata]. Calling this extension function outside of Kotlin
+ * requires an appropriate [MetadataProvider], such as a [LanguageFrontend] as an additional
+ * prepended argument.
+ */
+@JvmOverloads
+fun MetadataProvider.newOperatorCallExpression(
+    operatorCode: String,
+    callee: Expression?,
+    rawNode: Any? = null
+): OperatorCallExpression {
+    val node = OperatorCallExpression()
+    node.applyMetadata(this, operatorCode, rawNode)
+
+    node.operatorCode = operatorCode
+    node.callee = callee
+
+    log(node)
+    return node
+}
+
 /**
  * Creates a new [MemberCallExpression]. The [MetadataProvider] receiver will be used to fill
  * different meta-data using [Node.applyMetadata]. Calling this extension function outside of Kotlin

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/Interfaces.kt

@@ -149,4 +149,4 @@ interface HasCallableArguments : HasLanguage, HasNameAndLocation, HasScope {
  * Specifies that this node (e.g. a [BinaryOperator] contains an operation that can be overloaded by
  * an [OperatorDeclaration].
  */
-interface HasOverloadedOperation : HasBase
+interface HasOverloadedOperation : HasCallableArguments, HasBase, HasType

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/edge/PropertyEdge.kt

@@ -370,7 +370,7 @@ open class PropertyEdge<T : Node> : Persistable {
 @Transient
 class PropertyEdgeDelegate<T : Node, S : Node>(
     val edge: KProperty1<S, List<PropertyEdge<T>>>,
-    val outgoing: Boolean = true
+    val outgoing: Boolean = true,
 ) {
     operator fun getValue(thisRef: S, property: KProperty<*>): List<T> {
         return PropertyEdge.unwrap(edge.get(thisRef), outgoing)

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/statements/expressions/BinaryOperator.kt

@@ -72,6 +72,9 @@ open class BinaryOperator :
             }
         }
 
+    override val arguments
+        get() = listOf(rhs)
+
     private fun connectNewLhs(lhs: Expression) {
         lhs.registerTypeObserver(this)
         if (lhs is Reference && "=" == operatorCode) {

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/statements/expressions/MemberExpression.kt

@@ -25,12 +25,8 @@
  */
 package de.fraunhofer.aisec.cpg.graph.statements.expressions
 
-import de.fraunhofer.aisec.cpg.graph.AST
-import de.fraunhofer.aisec.cpg.graph.ArgumentHolder
-import de.fraunhofer.aisec.cpg.graph.HasBase
-import de.fraunhofer.aisec.cpg.graph.HasOverloadedOperation
+import de.fraunhofer.aisec.cpg.graph.*
 import de.fraunhofer.aisec.cpg.graph.declarations.RecordDeclaration
-import de.fraunhofer.aisec.cpg.graph.fqn
 import de.fraunhofer.aisec.cpg.graph.types.HasType
 import de.fraunhofer.aisec.cpg.graph.types.Type
 import java.util.Objects
@@ -98,4 +94,11 @@ class MemberExpression : Reference(), HasOverloadedOperation, ArgumentHolder, Ha
     private fun updateName() {
         this.name = base.type.root.name.fqn(name.localName)
     }
+
+    /**
+     * This is actually just needed for operator overloading to member access expressions (which is
+     * possible in languages, such as C++). The arguments are always empty.
+     */
+    override val arguments: List<Expression>
+        get() = listOf()
 }

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/statements/expressions/OperatorCallExpression.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2024, Fraunhofer AISEC. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ *                    $$$$$$\  $$$$$$$\   $$$$$$\
+ *                   $$  __$$\ $$  __$$\ $$  __$$\
+ *                   $$ /  \__|$$ |  $$ |$$ /  \__|
+ *                   $$ |      $$$$$$$  |$$ |$$$$\
+ *                   $$ |      $$  ____/ $$ |\_$$ |
+ *                   $$ |  $$\ $$ |      $$ |  $$ |
+ *                   \$$$$$   |$$ |      \$$$$$   |
+ *                    \______/ \__|       \______/
+ *
+ */
+package de.fraunhofer.aisec.cpg.graph.statements.expressions
+
+import de.fraunhofer.aisec.cpg.graph.HasBase
+import de.fraunhofer.aisec.cpg.graph.HasOperatorCode
+import de.fraunhofer.aisec.cpg.graph.Name
+import de.fraunhofer.aisec.cpg.graph.declarations.OperatorDeclaration
+
+/**
+ * This special call expression is used when an operator (such as a [BinaryOperator]) is overloaded.
+ * In this case, we replace the original [BinaryOperator] with an [OperatorCallExpression], which
+ * points to its respective [OperatorDeclaration].
+ */
+class OperatorCallExpression : CallExpression(), HasOperatorCode, HasBase {
+
+    override var operatorCode: String? = null
+
+    override var name: Name
+        get() = Name(operatorCode ?: "")
+        set(_) {}
+
+    /**
+     * The base object. This is basically a shortcut to accessing the base of the [callee], if it
+     * has one (i.e., if it implements [HasBase]). This is the case for example, if it is a
+     * [MemberExpression].
+     */
+    override val base: Expression?
+        get() {
+            return (callee as? HasBase)?.base
+        }
+}

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/graph/statements/expressions/UnaryOperator.kt

@@ -25,11 +25,7 @@
  */
 package de.fraunhofer.aisec.cpg.graph.statements.expressions
 
-import de.fraunhofer.aisec.cpg.graph.AST
-import de.fraunhofer.aisec.cpg.graph.AccessValues
-import de.fraunhofer.aisec.cpg.graph.ArgumentHolder
-import de.fraunhofer.aisec.cpg.graph.HasOverloadedOperation
-import de.fraunhofer.aisec.cpg.graph.pointer
+import de.fraunhofer.aisec.cpg.graph.*
 import de.fraunhofer.aisec.cpg.graph.types.HasType
 import de.fraunhofer.aisec.cpg.graph.types.Type
 import org.apache.commons.lang3.builder.ToStringBuilder
@@ -63,6 +59,8 @@ class UnaryOperator : Expression(), HasOverloadedOperation, ArgumentHolder, HasT
     /** Specifies, whether this a pre fix operation. */
     var isPrefix = false
 
+    override val arguments = listOf<Expression>()
+
     private fun changeExpressionAccess() {
         var access = AccessValues.READ
         if (operatorCode == "++" || operatorCode == "--") {

cpg-core/src/main/kotlin/de/fraunhofer/aisec/cpg/passes/SymbolResolver.kt

@@ -341,7 +341,38 @@ open class SymbolResolver(ctx: TranslationContext) : ComponentPass(ctx) {
             return null
         }
         var member: ValueDeclaration? = null
-        val record = containingClass.recordDeclaration
+        var type = containingClass
+
+        // Check for a possible overloaded operator-> (C++ only?!)
+        if (
+            reference.language is HasOperatorOverloading &&
+                reference is MemberExpression &&
+                reference.operatorCode == "->" &&
+                reference.base.type !is PointerType
+        ) {
+            var op =
+                resolveCalleeByName("operator->", reference)
+                    .filterIsInstance<OperatorDeclaration>()
+                    .singleOrNull()
+
+            if (op != null) {
+                type = op.returnTypes.singleOrNull()?.root ?: unknownType()
+
+                // We need to insert a new operator call expression in between
+                val ref =
+                    newMemberExpression(op.name, reference.base, operatorCode = ".")
+                        .implicit(op.name.localName, location = reference.location)
+                ref.refersTo = op
+                var call =
+                    newOperatorCallExpression(operatorCode = "->", ref).codeAndLocationFrom(ref)
+                call.invokes = listOf(op)
+
+                // Make the call our new base
+                reference.base = call
+            }
+        }
+
+        val record = type.recordDeclaration
         if (record != null) {
             member =
                 record.fields
@@ -351,8 +382,8 @@ open class SymbolResolver(ctx: TranslationContext) : ComponentPass(ctx) {
         }
         if (member == null) {
             member =
-                (containingClass.recordDeclaration?.superTypeDeclarations?.flatMap { it.fields }
-                        ?: listOf())
+                type.superTypes
+                    .flatMap { it.recordDeclaration?.fields ?: listOf() }
                     .filter { it.name.localName == reference.name.localName }
                     .map { it.definition }
                     .firstOrNull()
@@ -446,6 +477,7 @@ open class SymbolResolver(ctx: TranslationContext) : ComponentPass(ctx) {
             is Reference -> handleReference(currClass, node)
             is ConstructExpression -> handleConstructExpression(node)
             is CallExpression -> handleCallExpression(node)
+            is HasOverloadedOperation -> handleOverloadedOperator(node)
         }
     }
 
@@ -645,6 +677,27 @@ open class SymbolResolver(ctx: TranslationContext) : ComponentPass(ctx) {
         }
     }
 
+    private fun handleOverloadedOperator(operator: HasOverloadedOperation) {
+        val language = operator.language
+        if (language !is HasOperatorOverloading || language.isPrimitive(operator.type)) {
+            return
+        }
+
+        val symbol = language.overloadedOperatorNames[Pair(operator::class, operator.operatorCode)]
+        if (symbol == null) {
+            log.warn(
+                "Could not resolve operator overloading for unknown operatorCode ${operator.operatorCode}"
+            )
+            return
+        }
+
+        // operator.invokes =
+        //    resolveCalleeByName(symbol, operator).filterIsInstance<OperatorDeclaration>()
+        // TODO: replace with call
+        val ops = resolveCalleeByName(symbol, operator).filterIsInstance<OperatorDeclaration>()
+        println(ops)
+    }
+
     /**
      * Returns a set of types in which the callee of our [call] could reside in. More concretely, it
      * returns a [Pair], where the first element is the set of types and the second is our best
@@ -653,19 +706,19 @@ open class SymbolResolver(ctx: TranslationContext) : ComponentPass(ctx) {
     protected fun getPossibleContainingTypes(call: HasCallableArguments): Pair<Set<Type>, Type?> {
         val possibleTypes = mutableSetOf<Type>()
         var bestGuess: Type? = null
-        if (call is MemberCallExpression) {
-            call.base?.let { base ->
-                bestGuess = base.type
-                possibleTypes.add(base.type)
-                possibleTypes.addAll(base.assignedTypes)
-            }
-        } else {
+        if (call is CallExpression && call !is MemberCallExpression) {
             // This could be a C++ member call with an implicit this (which we do not create), so
             // let's add the current class to the possible list
             scopeManager.currentRecord?.toType()?.let {
                 bestGuess = it
                 possibleTypes.add(it)
             }
+        } else if (call is HasBase) {
+            call.base?.let { base ->
+                bestGuess = base.type
+                possibleTypes.add(base.type)
+                possibleTypes.addAll(base.assignedTypes)
+            }
         }
 
         return Pair(possibleTypes, bestGuess)

cpg-language-cxx/src/main/kotlin/de/fraunhofer/aisec/cpg/frontends/cxx/CLanguage.kt

@@ -27,7 +27,6 @@ package de.fraunhofer.aisec.cpg.frontends.cxx
 
 import com.fasterxml.jackson.annotation.JsonIgnore
 import de.fraunhofer.aisec.cpg.frontends.*
-import de.fraunhofer.aisec.cpg.graph.declarations.ParameterDeclaration
 import de.fraunhofer.aisec.cpg.graph.types.*
 import kotlin.reflect.KClass
 import org.neo4j.ogm.annotation.Transient
@@ -130,18 +129,6 @@ open class CLanguage :
             return ImplicitCast
         }
 
-        // Another special rule is that if we have a const reference (e.g. const T&) in a function
-        // call, this will match the type T because this means that the parameter is given by
-        // reference rather than by value.
-        if (
-            targetType is ReferenceType &&
-                targetType.elementType == type &&
-                targetHint is ParameterDeclaration &&
-                CONST in targetHint.modifiers
-        ) {
-            return DirectMatch
-        }
-
         return CastNotPossible
     }
 }

cpg-language-cxx/src/main/kotlin/de/fraunhofer/aisec/cpg/frontends/cxx/CPPLanguage.kt

@@ -25,19 +25,23 @@
  */
 package de.fraunhofer.aisec.cpg.frontends.cxx
 
+import de.fraunhofer.aisec.cpg.CallResolutionResult
+import de.fraunhofer.aisec.cpg.SignatureMatches
 import de.fraunhofer.aisec.cpg.TranslationContext
 import de.fraunhofer.aisec.cpg.frontends.*
 import de.fraunhofer.aisec.cpg.graph.HasOverloadedOperation
 import de.fraunhofer.aisec.cpg.graph.Node
 import de.fraunhofer.aisec.cpg.graph.declarations.*
 import de.fraunhofer.aisec.cpg.graph.edge.Properties
+import de.fraunhofer.aisec.cpg.graph.primitiveType
 import de.fraunhofer.aisec.cpg.graph.scopes.Symbol
 import de.fraunhofer.aisec.cpg.graph.statements.expressions.BinaryOperator
 import de.fraunhofer.aisec.cpg.graph.statements.expressions.CallExpression
 import de.fraunhofer.aisec.cpg.graph.statements.expressions.MemberCallExpression
 import de.fraunhofer.aisec.cpg.graph.statements.expressions.MemberExpression
 import de.fraunhofer.aisec.cpg.graph.statements.expressions.UnaryOperator
 import de.fraunhofer.aisec.cpg.graph.types.*
+import de.fraunhofer.aisec.cpg.matchesSignature
 import de.fraunhofer.aisec.cpg.passes.*
 import de.fraunhofer.aisec.cpg.passes.inference.startInference
 import kotlin.reflect.KClass
@@ -171,6 +175,17 @@ open class CPPLanguage :
             return match
         }
 
+        // Another special rule is that if we have a (const) reference (e.g. const T&) in a function
+        // call, this will match the type T because this means that the parameter is given by
+        // reference rather than by value.
+        if (
+            targetType is ReferenceType &&
+                targetType.elementType == type &&
+                targetHint is ParameterDeclaration
+        ) {
+            return DirectMatch
+        }
+
         // In C++, it is possible to have conversion constructors. We will not have full support for
         // them yet, but at least we should have some common cases here, such as const char* to
         // std::string
@@ -185,6 +200,27 @@ open class CPPLanguage :
         return CastNotPossible
     }
 
+    override fun bestViableResolution(
+        result: CallResolutionResult
+    ): Pair<Set<FunctionDeclaration>, CallResolutionResult.SuccessKind> {
+        // There is a sort of weird workaround in C++ to select a prefix vs. postfix operator for
+        // increment and decrement operators. See
+        // https://en.cppreference.com/w/cpp/language/operator_incdec
+        val expr = result.call
+        if (expr is UnaryOperator && (expr.operatorCode == "++" || expr.operatorCode == "--")) {
+            // If it is a postfix, we need to match for a function with a fake "int" parameter
+            if (expr.isPostfix) {
+                result.signatureResults =
+                    result.candidateFunctions
+                        .map { Pair(it, it.matchesSignature(listOf(primitiveType("int")))) }
+                        .filter { it.second is SignatureMatches }
+                        .associate { it }
+            }
+        }
+
+        return super.bestViableResolution(result)
+    }
+
     override val startCharacter = '<'
     override val endCharacter = '>'