Add test cases for CXX ambiguities (#682)

* Add test case for function pointer vs type cast ambiguity
* Add test case MemberCallExpression vs CallExpression ambiguity
* Update README.md

Co-authored-by: Christian Banse <[email protected]>

README.md

@@ -127,6 +127,7 @@ The following authors have contributed to this project (in alphabetical order):
 * [maximiliankaul](https://github.com/maximiliankaul)
 * [obraunsdorf](https://github.com/obraunsdorf)
 * [oxisto](https://github.com/oxisto)
+* [peckto](https://github.com/peckto)
 * [titze](https://github.com/titze)
 * [vfsrfs](https://github.com/vfsrfs)
 

cpg-core/src/test/java/de/fraunhofer/aisec/cpg/frontends/cpp/CXXAmbiguitiesTest.kt

@@ -28,10 +28,14 @@ package de.fraunhofer.aisec.cpg.frontends.cpp
 import de.fraunhofer.aisec.cpg.TestUtils
 import de.fraunhofer.aisec.cpg.graph.bodyOrNull
 import de.fraunhofer.aisec.cpg.graph.byNameOrNull
+import de.fraunhofer.aisec.cpg.graph.declarations.FunctionDeclaration
 import de.fraunhofer.aisec.cpg.graph.declarations.MethodDeclaration
 import de.fraunhofer.aisec.cpg.graph.declarations.ProblemDeclaration
 import de.fraunhofer.aisec.cpg.graph.declarations.RecordDeclaration
 import de.fraunhofer.aisec.cpg.graph.statements.DeclarationStatement
+import de.fraunhofer.aisec.cpg.graph.statements.expressions.CallExpression
+import de.fraunhofer.aisec.cpg.graph.statements.expressions.CastExpression
+import de.fraunhofer.aisec.cpg.graph.statements.expressions.MemberCallExpression
 import java.io.File
 import kotlin.test.assertContains
 import kotlin.test.assertEquals
@@ -76,4 +80,61 @@ class CXXAmbiguitiesTest {
         assertNotNull(problem)
         assertContains(problem.problem, "CDT")
     }
+
+    /**
+     * In CXX there is an ambiguity with the statement: "(A)(B);" 1) If A is a function pointer,
+     * this is a [CallExpression] 2) If A is a type, this is a [CastExpression]
+     */
+    @Test
+    fun testFunctionCallOrTypeCast() {
+        val file = File("src/test/resources/function_ptr_or_type_cast.c")
+        val tu = TestUtils.analyzeAndGetFirstTU(listOf(file), file.parentFile.toPath(), true)
+        assertNotNull(tu)
+
+        val mainFunc = tu.byNameOrNull<FunctionDeclaration>("main")
+        assertNotNull(mainFunc)
+
+        val fooFunc = tu.byNameOrNull<FunctionDeclaration>("foo")
+        assertNotNull(fooFunc)
+
+        // First two Statements are CallExpressions
+        val s1 = mainFunc.getBodyStatementAs(1, CallExpression::class.java)
+        assertNotNull(s1)
+        assertEquals(s1.invokes.iterator().next(), fooFunc)
+
+        val s2 = mainFunc.getBodyStatementAs(2, CallExpression::class.java)
+        assertNotNull(s2)
+        assertEquals(s2.invokes.iterator().next(), fooFunc)
+
+        // Last two Statements are CastExpressions
+        val s3 = mainFunc.getBodyStatementAs(3, CastExpression::class.java)
+        assertNotNull(s3)
+
+        val s4 = mainFunc.getBodyStatementAs(4, CastExpression::class.java)
+        assertNotNull(s4)
+    }
+
+    /**
+     * In CXX there is an ambiguity with the statement: "(A.B)(C);" 1) If B is a method, this is a
+     * [MemberCallExpression] 2) if B is a function pointer, this is a [CallExpression].
+     *
+     * Function pointer as a struct member are currently not supported in the cpg. This test case
+     * will just ensure that there will be no crash when parsing such a statement. When adding this
+     * functionality in the cpg, this test case must be adapted accordingly.
+     */
+    @Test
+    fun testMethodOrFunction() {
+        val file = File("src/test/resources/method_or_function_call.cpp")
+        val tu = TestUtils.analyzeAndGetFirstTU(listOf(file), file.parentFile.toPath(), true)
+        assertNotNull(tu)
+
+        val mainFunc = tu.byNameOrNull<FunctionDeclaration>("main")
+        assertNotNull(mainFunc)
+
+        val classA = tu.byNameOrNull<RecordDeclaration>("A")
+        assertNotNull(classA)
+
+        val structB = tu.byNameOrNull<RecordDeclaration>("B")
+        assertNotNull(structB)
+    }
 }

cpg-core/src/test/resources/function_ptr_or_type_cast.c

@@ -0,0 +1,22 @@
+void foo(int i) {
+}
+
+struct S {
+    int a;
+} typedef s_t;
+
+typedef s_t* s_t_p;
+
+int main() {
+    void (*ptr)(int) = &foo;
+
+    // this is a function call
+    (*ptr)(1);
+    (ptr)(2);
+
+    // this is a type case
+    (int)(3);
+    (s_t_p)(4);
+
+    return 0;
+}

cpg-core/src/test/resources/method_or_function_call.cpp

@@ -0,0 +1,27 @@
+struct A {
+    void foo(int i) {
+    }
+};
+
+struct B {
+    void (*bar)(int);
+};
+
+void bar(int i) {
+}
+
+int main() {
+    A a;
+    B b;
+    b.bar = &bar;
+
+    // foo is a method
+    (a.foo)(1);
+    a.foo(2);
+
+    // bar is a function
+    (b.bar)(3);
+    (*b.bar)(3);
+
+    return 0;
+}