Guard against basic T::value_type recursion, fixes #90

include/libassert/assert.hpp

@@ -573,7 +573,11 @@ namespace libassert::detail {
     template<typename T> constexpr bool stringifiable_container() {
         // TODO: Guard against std::expected....?
         if constexpr(has_value_type<T>::value) {
-            return stringifiable<typename T::value_type>;
+            if constexpr(std::is_same_v<typename T::value_type, T>) {
+                return false;
+            } else {
+                return stringifiable<typename T::value_type>;
+            }
         } else if constexpr(std::is_array_v<typename std::remove_reference_t<T>>) { // C arrays
             return stringifiable<decltype(std::declval<T>()[0])>;
         } else if constexpr(stringification::is_tuple_like<T>::value) {

tests/unit/stringify.cpp

@@ -13,6 +13,31 @@
 using namespace libassert::detail;
 using namespace std::literals;
 
+struct basic_fields {
+    struct value_type {
+        value_type() {}
+    };
+    struct const_iterator {
+        bool operator==(const const_iterator&) const {
+            return true;
+        }
+    };
+    const_iterator begin() {
+        return {};
+    }
+    const_iterator end() {
+        return {};
+    }
+};
+
+void regression01() {
+    // regression test for #90, just making sure this can compile
+    constexpr bool b = stringifiable_container<basic_fields::value_type>();
+    ASSERT(!b);
+    basic_fields fields;
+    ASSERT(fields.begin() == fields.end());
+}
+
 struct S {};
 struct S2 {};
 
@@ -124,4 +149,6 @@ int main() {
     // libfmt
     // std::format
     // stringification tests
+
+    regression01();
 }