Using system libraries in C++ targets with SwiftPM

[code-per-day]

I'm trying to use curl by creating a system library target and adding it as a dependency to my C++ target.

I can't include any of the headers, is this supported?

// swift-tools-version: 5.9

import PackageDescription

let package = Package(
    name: "CxxProject",
    platforms: [
        .iOS(.v14),
    ],
    products: [
        .library(
            name: "CxxProject",
            targets: ["CxxProject"]),
    ],
    targets: [
        .systemLibrary(
            name: "libcurl",
            path: "Dependencies/curl",
            pkgConfig: "curl",
            providers: [.brew(["curl"])]),

        .target(
            name: "CxxProject",
            dependencies: ["libcurl"]),
    ],
    cxxLanguageStandard: .cxx14
)

[code-per-day]

Update to this, I'm now bundling an xcframework imported via .binaryTarget but I'm getting an issue with non-modular includes within curl/curl.h.

// Include of non-modular header inside framework module 'curl'
#include <limits.h>

I have (and need) the following unsafe flags. Is there a way to apply different flags to curl or link dynamically rather than statically?

.unsafeFlags(["-x", "objective-c++", "-fno-objc-arc", "-fmodules", "-fcxx-modules"]