C++: Silence alerts coming from CMake test compilation files

cpp/ql/lib/semmle/code/cpp/ConfigurationTestFile.qll

@@ -0,0 +1,28 @@
+/**
+ * Provides classes for identifying files that created to test the
+ * build configuration. It is often desirable to exclude these files
+ * from analysis.
+ */
+
+import File
+
+/**
+ * A file created to test the system configuration.
+ */
+abstract class ConfigurationTestFile extends File { }
+
+/**
+ * A file created by CMake to test the system configuration.
+ */
+class CmakeTryCompileFile extends ConfigurationTestFile {
+  CmakeTryCompileFile() {
+    exists(Folder folder, Folder parent |
+      folder = this.getParentContainer() and
+      parent = folder.getParentContainer()
+    |
+      folder.getBaseName().matches("TryCompile-%") and
+      parent.getBaseName() = "CMakeScratch" and
+      parent.getParentContainer().getBaseName() = "CMakeFiles"
+    )
+  }
+}