Compare ABI entries by their type and name as strings

The ABI entries were ordered by comparing tuples of JSON values, which
uses operator<=>. Where nlohmann::json has no three-way comparison
because the standard library lacks it, as in the emscripten build, and
implicit conversions are disabled, that resolves to the implicit
conversion of both values to their value_t and compares only their
types. The emscripten build then left the ABI unsorted.

Author: djolertrk

libsolidity/interface/ABI.cpp

@@ -40,10 +40,12 @@ bool anyDataStoredInStorage(TypePointers const& _pointers)
 
 Json ABI::generate(ContractDefinition const& _contractDef)
 {
+	// Compare the keys as strings: tuples compare JSON values with operator<=>, which, without
+	// three-way comparison support in nlohmann::json, resolves to comparing only their types.
 	auto compare = [](Json const& _a, Json const& _b) -> bool
 	{
-		return std::make_tuple(_a.value("type", Json()), _a.value("name", Json())) <
-					std::make_tuple(_b.value("type", Json()), _b.value("name", Json()));
+		return std::make_tuple(_a.value("type", std::string{}), _a.value("name", std::string{})) <
+					std::make_tuple(_b.value("type", std::string{}), _b.value("name", std::string{}));
 	};
 	std::multiset<Json, decltype(compare)> abi(compare);