📝 overwork project infrastructure

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

tests/module_cpp20/main.cpp

@@ -8,7 +8,50 @@
 
 import nlohmann.json;
 
+#include <sstream>
+#include <string>
+
+using namespace nlohmann::literals;
+
+// Exercise each name exported by the nlohmann.json module so that a missing or
+// broken export is caught at compile time. This target is only built (not run)
+// by the ci_module_cpp20 CI job, so the checks are primarily compile-time; the
+// return value additionally validates them if the binary is executed.
 int main()
 {
-    nlohmann::json j;
+    // basic_json / json: parsing and value access
+    nlohmann::json j = nlohmann::json::parse(R"({"a": 1, "list": [1, 2, 3]})");
+    const int a = j["a"].get<int>();
+
+    // json_pointer and operator""_json_pointer
+    nlohmann::json_pointer<std::string> ptr = "/list/2"_json_pointer;
+    const int last = j[ptr].get<int>();
+
+    // operator""_json literal
+    const nlohmann::json lit = R"([1, 2, 3])"_json;
+
+    // ordered_json
+    nlohmann::ordered_json oj;
+    oj["b"] = 2;
+    const int b = oj["b"].get<int>();
+
+    // ordered_map alias
+    nlohmann::ordered_map<std::string, int> m;
+    m["x"] = 1;
+
+    // adl_serializer (reference the exported template)
+    using serializer = nlohmann::adl_serializer<int, void>;
+    static_cast<void>(sizeof(serializer));
+
+    // to_string
+    const std::string dumped = nlohmann::to_string(j);
+
+    // operator<< (hidden friend, reached via ADL through the module)
+    std::ostringstream os;
+    os << j << oj << lit;
+
+    // use every result so the references cannot be optimized away
+    return (a == 1 && last == 3 && b == 2 && lit.size() == 3
+            && m.size() == 1 && !dumped.empty() && !os.str().empty())
+        ? 0 : 1;
 }