SDK Extension for Rust stable

This extension contains various components of the Rust stable toolchain.

Mold

In order to use the (fast) mold linker:

1. Add org.freedesktop.Sdk.Extension.llvm16 along with this extension in order to get clang.
2. Add /usr/lib/sdk/llvm16/bin to append-path. See llvm16 SDK extension readme for more information.
3. Set environment variables:
   • CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER to clang, and
   • CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUSTFLAGS to -C link-arg=-fuse-ld=/usr/lib/sdk/rust-stable/bin/mold.

In total, the changed parts of your flatpak manifest should look like this:

{
    "sdk-extensions": [
        "org.freedesktop.Sdk.Extension.rust-stable",
        "org.freedesktop.Sdk.Extension.llvm16"
    ],
    "build-options": {
        "append-path": "/usr/lib/sdk/rust-stable/bin:/usr/lib/sdk/llvm16/bin",
        "env": {
            "CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER": "clang",
            "CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUSTFLAGS": "-C link-arg=-fuse-ld=/usr/lib/sdk/rust-stable/bin/mold",
            "CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER": "clang",
            "CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_RUSTFLAGS": "-C link-arg=-fuse-ld=/usr/lib/sdk/rust-stable/bin/mold"
        }
    }
}

Note: llvm16 is needed until there is a release of gcc12.1. As soon as gcc12.1 is in the freedesktop sdk, gcc can be used instead of clang.

Debugging/Development

In order to use this extension in flatpak SDK environment you may add all provided tools in your PATH by executing first:

source /usr/lib/sdk/rust-stable/enable.sh

You can also combine this extension with lldb using the LLVM SDK extension. See the extension's readme for more information.