---
title: "SE-0181: Package Manager C/C++ Language Standard Support"
framework: swift-evolution
role: article
path: swift-evolution/0181-package-manager-cpp-language-version
---

# SE-0181: Package Manager C/C++ Language Standard Support

* Proposal: [SE-0181](0181-package-manager-cpp-language-version.md)
* Author: [Ankit Aggarwal](https://github.com/aciidb0mb3r)
* Review Manager: [Daniel Dunbar](https://github.com/ddunbar)
* Status: **Implemented (Swift 4.0)**
* Decision Notes: [Rationale](https://forums.swift.org/t/accepted-with-revision-se-0181-package-manager-c-c-language-standard-support/6353)
* Implementation: [apple/swift-package-manager#1264](https://github.com/apple/swift-package-manager/pull/1264)

## Introduction

This proposal adds support for declaring the language standard for C and C++ targets in a SwiftPM package.

## Motivation

The C++ language standard is one of the most important build setting needed to compile C++ targets. We want to add some mechanism to declare it until we get the complete build settings feature, which is deferred from the Swift 4 release.

## Proposed solution

We will add support to the package manifest declaration to specify the C and C++ language standards:

```swift let package = Package(     name: "CHTTP",     ...     cLanguageStandard: .c89,     cxxLanguageStandard: .cxx11 ) ```

These settings will apply to all the C and C++ targets in the package. The default value of these properties will be `nil`, i.e., a language standard flag will not be passed when invoking the C/C++ compiler.

_Once we get the build settings feature, we will deprecate these properties._

## Detailed design

The C/C++ language standard will be defined by the enums below and updated as per the Clang compiler [repository](https://github.com/llvm-mirror/clang/blob/master/include/clang/Frontend/LangStandards.def).

```swift public enum CLanguageStandard {     case c89     case c90     case iso9899_1990     case iso9899_199409     case gnu89     case gnu90     case c99     case iso9899_1999     case gnu99     case c11     case iso9899_2011     case gnu11 }

public enum CXXLanguageStandard {     case cxx98     case cxx03     case gnucxx98     case gnucxx03     case cxx11     case gnucxx11     case cxx14     case gnucxx14     case cxx1z     case gnucxx1z } ```

## Impact on existing code

There will be no impact on existing packages because this is a new API and the default behaviour remains unchanged.

## Alternatives considered

We considered adding this property at target level but we think that will pollute the target namespace. Moreover, this is a temporary measure until we get the build settings feature.