[codex] Add runtime string format opt-ins

smoke/CMakeLists.txt

@@ -12,6 +12,7 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
 include(FetchContent)
+include(CheckCXXSourceCompiles)
 
 set(PROTOCYTE_REPO_ROOT "${CMAKE_CURRENT_LIST_DIR}/..")
 set(PROTOCYTE_SMOKE_PROTO_DIR "${CMAKE_CURRENT_LIST_DIR}/proto")
@@ -42,6 +43,29 @@ set(PROTOCYTE_GENERATED_FILES
     "${PROTOCYTE_GENERATED_DIR}/protocyte/runtime/runtime.hpp"
 )
 
+check_cxx_source_compiles([=[
+#include <version>
+#if !defined(__cpp_lib_format) || __cpp_lib_format < 201907L
+#error "std::format is unavailable"
+#endif
+#include <format>
+#include <string_view>
+#include <type_traits>
+
+int main() {
+    using Formatter = ::std::formatter<::std::string_view, char>;
+    static_assert(::std::is_default_constructible_v<Formatter>);
+    const auto formatted = ::std::format("{}", ::std::string_view {"ok"});
+    return formatted == "ok" ? 0 : 1;
+}
+]=] PROTOCYTE_SMOKE_HAS_STD_FORMAT)
+
+function(protocyte_smoke_enable_std_format_if_available target_name)
+    if(PROTOCYTE_SMOKE_HAS_STD_FORMAT)
+        target_compile_definitions("${target_name}" PRIVATE PROTOCYTE_ENABLE_STD_FORMAT=1)
+    endif()
+endfunction()
+
 if(PROTOCYTE_SMOKE_REGENERATE OR PROTOCYTE_SMOKE_BUILD_BENCHMARKS)
     set(PROTOCYTE_FETCH_PROTOBUF "${PROTOCYTE_SMOKE_FETCH_PROTOBUF}")
 else()
@@ -212,6 +236,7 @@ target_compile_definitions(
         PROTOCYTE_ENABLE_HOSTED_ALLOCATOR=1
         PROTOCYTE_ENABLE_STD_STRING_VIEW=1
 )
+protocyte_smoke_enable_std_format_if_available(protocyte_host_smoke)
 target_compile_features(protocyte_host_smoke PRIVATE cxx_std_20)
 target_link_libraries(protocyte_host_smoke PRIVATE Catch2::Catch2WithMain)
 
@@ -239,6 +264,7 @@ if(PROTOCYTE_SMOKE_BUILD_BENCHMARKS)
             PROTOCYTE_ENABLE_HOSTED_ALLOCATOR=1
             PROTOCYTE_ENABLE_STD_STRING_VIEW=1
     )
+    protocyte_smoke_enable_std_format_if_available(protocyte_host_benchmark)
     target_compile_features(protocyte_host_benchmark PRIVATE cxx_std_20)
     target_link_libraries(protocyte_host_benchmark PRIVATE benchmark::benchmark_main)
 
@@ -268,6 +294,7 @@ if(PROTOCYTE_SMOKE_BUILD_BENCHMARKS)
             PROTOCYTE_ENABLE_HOSTED_ALLOCATOR=1
             PROTOCYTE_ENABLE_STD_STRING_VIEW=1
     )
+    protocyte_smoke_enable_std_format_if_available(protocyte_host_protobuf_benchmark)
     target_compile_features(protocyte_host_protobuf_benchmark PRIVATE cxx_std_20)
     target_link_libraries(
         protocyte_host_protobuf_benchmark

smoke/generated/protocyte/runtime/runtime.hpp

@@ -11,7 +11,14 @@
 #include <new>
 #include <type_traits>
 
-#if PROTOCYTE_ENABLE_STD_STRING_VIEW
+#if PROTOCYTE_ENABLE_STD_FORMAT
+#include <version>
+#if defined(__cpp_lib_format) && __cpp_lib_format >= 201907L
+#include <format>
+#endif
+#endif
+
+#if PROTOCYTE_ENABLE_STD_STRING_VIEW || PROTOCYTE_ENABLE_STD_FORMAT || PROTOCYTE_ENABLE_FMT_FORMAT
 #include <string_view>
 #endif
 
@@ -2974,6 +2981,12 @@ namespace protocyte {
         typename Config::Bytes bytes_;
     };
 
+#if PROTOCYTE_ENABLE_FMT_FORMAT
+    template<class Config> std::string_view format_as(const String<Config> &value) noexcept {
+        return ::std::string_view {value.data(), value.size()};
+    }
+#endif
+
     template<class T, class Config> struct Box {
         using Context = typename Config::Context;
 
@@ -4299,4 +4312,18 @@ namespace protocyte {
 
 } // namespace protocyte
 
+#if PROTOCYTE_ENABLE_STD_FORMAT && defined(__cpp_lib_format) && __cpp_lib_format >= 201907L
+namespace std {
+
+    template<class Config> struct formatter<::protocyte::String<Config>, char>
+        : public ::std::formatter<::std::string_view, char> {
+        template<class FormatContext> auto format(const ::protocyte::String<Config> &value, FormatContext &ctx) const {
+            return ::std::formatter<::std::string_view, char>::format(::std::string_view {value.data(), value.size()},
+                                                                      ctx);
+        }
+    };
+
+} // namespace std
+#endif
+
 #endif // PROTOCYTE_RUNTIME_RUNTIME_HPP

smoke/src/host_smoke.cpp

@@ -2621,6 +2621,10 @@ TEST_CASE("byte setters accept contiguous byte containers", "[smoke][runtime][by
     CHECK(converted_span == std::string_view {"hello"});
 #if defined(__cpp_lib_format)
     CHECK(std::format("{}", message.f_string()) == "hello");
+#if PROTOCYTE_ENABLE_STD_FORMAT
+    CHECK(std::format("{}", message.mutable_f_string()) == "hello");
+    CHECK(std::format("{:>8}", message.mutable_f_string()) == "   hello");
+#endif
 #endif
     const std::string_view converted_string = message.mutable_f_string();
     CHECK(converted_string == converted_span);
@@ -2635,6 +2639,10 @@ TEST_CASE("byte setters accept contiguous byte containers", "[smoke][runtime][by
     REQUIRE(embedded_nul_string_view);
     CHECK(message.f_string().size() == 3u);
     CHECK(view_equal(message.f_string(), *embedded_nul_string_view));
+#if defined(__cpp_lib_format) && PROTOCYTE_ENABLE_STD_FORMAT
+    const auto formatted_embedded_nul = std::format("{}", message.mutable_f_string());
+    CHECK(formatted_embedded_nul == std::string {"a\0b", 3u});
+#endif
 
     const char *c_string_payload = "hello from pointer";
     require_success(message.set_f_string(c_string_payload));

src/protocyte/runtime/runtime.hpp

@@ -11,7 +11,14 @@
 #include <new>
 #include <type_traits>
 
-#if PROTOCYTE_ENABLE_STD_STRING_VIEW
+#if PROTOCYTE_ENABLE_STD_FORMAT
+#include <version>
+#if defined(__cpp_lib_format) && __cpp_lib_format >= 201907L
+#include <format>
+#endif
+#endif
+
+#if PROTOCYTE_ENABLE_STD_STRING_VIEW || PROTOCYTE_ENABLE_STD_FORMAT || PROTOCYTE_ENABLE_FMT_FORMAT
 #include <string_view>
 #endif
 
@@ -2974,6 +2981,12 @@ namespace protocyte {
         typename Config::Bytes bytes_;
     };
 
+#if PROTOCYTE_ENABLE_FMT_FORMAT
+    template<class Config> std::string_view format_as(const String<Config> &value) noexcept {
+        return ::std::string_view {value.data(), value.size()};
+    }
+#endif
+
     template<class T, class Config> struct Box {
         using Context = typename Config::Context;
 
@@ -4299,4 +4312,18 @@ namespace protocyte {
 
 } // namespace protocyte
 
+#if PROTOCYTE_ENABLE_STD_FORMAT && defined(__cpp_lib_format) && __cpp_lib_format >= 201907L
+namespace std {
+
+    template<class Config> struct formatter<::protocyte::String<Config>, char>
+        : public ::std::formatter<::std::string_view, char> {
+        template<class FormatContext> auto format(const ::protocyte::String<Config> &value, FormatContext &ctx) const {
+            return ::std::formatter<::std::string_view, char>::format(::std::string_view {value.data(), value.size()},
+                                                                      ctx);
+        }
+    };
+
+} // namespace std
+#endif
+
 #endif // PROTOCYTE_RUNTIME_RUNTIME_HPP

tests/test_cmake.py

@@ -131,6 +131,25 @@ def test_cmake_requires_python_314_for_codegen_wrapper() -> None:
     assert "find_package(Python3 3.14 COMPONENTS Interpreter REQUIRED)" in functions
 
 
+def test_smoke_cmake_gates_std_format_opt_in_on_compile_probe() -> None:
+    smoke_cmake = (Path(__file__).resolve().parents[1] / "smoke" / "CMakeLists.txt").read_text(encoding="utf-8")
+
+    assert "include(CheckCXXSourceCompiles)" in smoke_cmake
+    assert "check_cxx_source_compiles(" in smoke_cmake
+    assert "#include <version>" in smoke_cmake
+    assert "#if !defined(__cpp_lib_format) || __cpp_lib_format < 201907L" in smoke_cmake
+    assert '#error "std::format is unavailable"' in smoke_cmake
+    assert "#include <format>" in smoke_cmake
+    assert "#include <string_view>" in smoke_cmake
+    assert "::std::formatter<::std::string_view, char>" in smoke_cmake
+    assert "::std::format(\"{}\", ::std::string_view {\"ok\"})" in smoke_cmake
+    assert "PROTOCYTE_SMOKE_HAS_STD_FORMAT" in smoke_cmake
+    assert "if(PROTOCYTE_SMOKE_HAS_STD_FORMAT)" in smoke_cmake
+    assert "target_compile_definitions(\"${target_name}\" PRIVATE PROTOCYTE_ENABLE_STD_FORMAT=1)" in smoke_cmake
+    assert "\n        PROTOCYTE_ENABLE_STD_FORMAT=1" not in smoke_cmake
+    assert "\n            PROTOCYTE_ENABLE_STD_FORMAT=1" not in smoke_cmake
+
+
 def test_prerelease_cmake_version_file_marks_versioned_requests_unsuitable() -> None:
     template = (
         Path(__file__).resolve().parents[1] / "cmake" / "protocyteConfigVersionPrerelease.cmake.in"

tests/test_plugin.py

@@ -183,8 +183,11 @@ def test_runtime_byte_containers_use_bulk_copy_helpers() -> None:
     )[0]
 
     assert "#include <cstring>" in runtime_header
-    assert "#if PROTOCYTE_ENABLE_STD_STRING_VIEW\n#include <string_view>\n#endif" in runtime_header
+    assert "#if PROTOCYTE_ENABLE_STD_FORMAT\n#include <version>\n#if defined(__cpp_lib_format) && __cpp_lib_format >= 201907L\n#include <format>\n#endif\n#endif" in runtime_header
+    assert "#if PROTOCYTE_ENABLE_STD_STRING_VIEW || PROTOCYTE_ENABLE_STD_FORMAT || PROTOCYTE_ENABLE_FMT_FORMAT\n#include <string_view>\n#endif" in runtime_header
     assert "#ifdef PROTOCYTE_ENABLE_STD_STRING_VIEW" not in runtime_header
+    assert "#ifdef PROTOCYTE_ENABLE_STD_FORMAT" not in runtime_header
+    assert "#ifdef PROTOCYTE_ENABLE_FMT_FORMAT" not in runtime_header
     assert "inline void copy_bytes(u8 *dst, const u8 *src, const usize count) noexcept" in runtime_header
     assert "if (!count || dst == src)" in runtime_header
     assert "::std::memmove(dst, src, count);" in runtime_header
@@ -218,6 +221,12 @@ def test_runtime_byte_containers_use_bulk_copy_helpers() -> None:
     assert "const char *data() const noexcept" in string_body
     assert "usize length() const noexcept { return size(); }" in string_body
     assert "operator ::std::string_view() const noexcept { return view(); }" in string_body
+    assert "#if PROTOCYTE_ENABLE_FMT_FORMAT\n    template<class Config> std::string_view format_as(const String<Config> &value) noexcept" in runtime_header
+    assert "return ::std::string_view {value.data(), value.size()};" in runtime_header
+    assert "#if PROTOCYTE_ENABLE_STD_FORMAT && defined(__cpp_lib_format) && __cpp_lib_format >= 201907L\nnamespace std {" in runtime_header
+    assert "template<class Config> struct formatter<::protocyte::String<Config>, char>" in runtime_header
+    assert "public ::std::formatter<::std::string_view, char>" in runtime_header
+    assert "auto format(const ::protocyte::String<Config> &value, FormatContext &ctx) const" in runtime_header
     assert "Status assign(const Span<const char> view) noexcept" in string_body
     assert "Status assign(const Span<const u8> view) noexcept" in string_body
     assert "copy_bytes(out, data_ + pos_, count);" in slice_reader_body