CI fixes

Author: franzpoeschel

examples/14_json_template.cpp

@@ -3,10 +3,12 @@
 int main()
 {
     std::string config = R"(
-iteration_encoding = "variable_based"
-
-[json]
-mode = "template"
+{
+  "iteration_encoding": "variable_based",
+  "json": {
+    "mode": "template"
+  }
+}
 )";
 
     openPMD::Series writeTemplate(

src/IO/JSON/JSONIOHandlerImpl.cpp

@@ -72,7 +72,20 @@ namespace
             {
                 return T{};
             }
+#if defined(__INTEL_COMPILER)
+/*
+ * ICPC has trouble with if constexpr, thinking that return statements are
+ * missing afterwards. Deactivate the warning.
+ * Note that putting a statement here will not help to fix this since it will
+ * then complain about unreachable code.
+ * https://community.intel.com/t5/Intel-C-Compiler/quot-if-constexpr-quot-and-quot-missing-return-statement-quot-in/td-p/1154551
+ */
+#pragma warning(disable : 1011)
+        }
+#pragma warning(default : 1011)
+#else
         }
+#endif
 
         static constexpr char const *errorMsg = "JSON default value";
     };