Merge pull request #892 from hvitved/csharp/get-arg-for-param-bad-magic

C#: Prevent bad magic in `getArgumentForParameter()`

csharp/ql/src/semmle/code/csharp/exprs/Call.qll

@@ -76,6 +76,7 @@ class Call extends DotNet::Call, Expr, @call {
    * }
    * ```
    */
+  pragma[nomagic]
   override Expr getArgumentForParameter(DotNet::Parameter p) {
     getTarget().getAParameter() = p and
     (