C#: Add meta query for reporting calls to unsupported library methods

Author: hvitved

csharp/ql/src/meta/frameworks/UnsupportedExternalAPIs.ql

@@ -0,0 +1,23 @@
+/**
+ * @name Usage of unsupported external library API
+ * @description A call to an unsuppported external library API.
+ * @kind problem
+ * @problem.severity recommendation
+ * @tags meta
+ * @id csharp/meta/unsupported-external-api
+ * @precision very-low
+ */
+
+private import csharp
+private import semmle.code.csharp.dispatch.Dispatch
+private import semmle.code.csharp.dataflow.internal.FlowSummaryImpl as FlowSummaryImpl
+private import semmle.code.csharp.dataflow.internal.NegativeSummary
+private import Telemetry.ExternalApi
+
+from DispatchCall c, ExternalApi api
+where
+  c = api.getACall() and
+  not api.isUninteresting() and
+  not api.isSupported() and
+  not api instanceof FlowSummaryImpl::Public::NegativeSummarizedCallable
+select c, "Call to unsupported external API $@.", api, api.toString()