BGCS.Cpp2C 2.0.4

BGCS.Cpp2C

BGCS.Cpp2C generates an extern "C" ABI bridge for C++ classes, functions, explicit template instances, ownership types, and supported standard-library semantics. The resulting C surface can be consumed by P/Invoke and can optionally be passed directly to BGCS to generate matching C# bindings.

Common C/C++ is automatic. Complex semantics use the final extension architecture: declarative type/callable lowerings, typed lowering plugins, or explicit project-owned C shims. Unsupported or ambiguous constructs are diagnosed instead of being silently treated as blittable values; projects may explicitly accept reviewed or unsafe lowerings through LoweringSafetyPolicy.

Install

dotnet add package BGCS.Cpp2C

Command-line users can install the BindGen-CS .NET tool and run bindgen-cs bridge bridge.json; the tool already includes this package.

Generate from configuration

{
  "ConfigVersion": 1,
  "EntryFiles": ["include/library.hpp"],
  "AllowedHeaders": ["include/library.hpp"],
  "OutputPath": "GeneratedBridge",
  "LanguageStandard": "c++23",
  "GenerateBuildManifest": true,
  "GenerateCSharpBindings": true,
  "CSharpNamespace": "Example.Native",
  "CSharpApiName": "NativeApi",
  "NativeLibraryName": "example",
  "CSharpOutputPath": "GeneratedBindings",
  "CSharpStrictSafetySeverity": "SuppressFriendly",
  "LoweringSafetyPolicy": "VerifiedOnly",
  "TypeLowerings": [],
  "CallableLowerings": [],
  "NativeShims": [],
  "PluginAssemblies": []
}

using BGCS.Cpp2C;

Cpp2CGeneratorConfig config = Cpp2CGeneratorConfig.Load("bridge.json");
Cpp2CCodeGenerator generator = new(config);
generator.GenerateConfigured();

if (generator.LastResult is { Success: false } result)
{
    foreach (var diagnostic in result.Diagnostics)
        Console.Error.WriteLine(diagnostic);
}

Configuration paths are resolved relative to bridge.json. The bridge output contains C-facing headers, src/Classes.cpp, and a deterministic bridge.manifest.json with target, source, include, definition, compiler/linker, language-standard, and library inputs. The BindGen-CS tool can compile this manifest with native-build; embedded consumers can use ClangNativeBuildProvider and NativeBuildExecutor directly.

Verified bridge scope

The regression suite covers constructors/destructors, instance and static methods, overloads, namespace functions, exception boundaries, pointer-adjusting multiple inheritance, explicit class and function template instances, std::string, std::vector, std::span, std::array, std::map, std::set, std::optional, std::variant, std::expected, std::filesystem::path, std::chrono, std::unique_ptr, std::shared_ptr, and configured pure-virtual callback proxies.

Unknown template specializations and undeclared ownership or allocator contracts remain explicit boundaries. VerifiedOnly rejects project-supplied assumptions. AllowUserAsserted accepts reviewed project contracts. AllowUnsafe continues with an auditable BGCS-SAFETY-LOWERING-BYPASS warning; it transfers risk but cannot make an unrepresentable ABI valid.

Documentation

• C++ quick start
• Capabilities and boundaries
• C++ configuration catalog
• Final lowering architecture
• C++ extension cookbook
• Diagnostics

BindGen-CS is licensed under the MIT License. Portions derived from CppAst/HexaGen retain their original notices.