aya-build: plumb features of ebpf crates

This allows callers to select features of the ebpf crate.

aya-build/src/lib.rs

@@ -11,9 +11,12 @@ use std::{
 use anyhow::{Context as _, Result, anyhow};
 use cargo_metadata::{Artifact, CompilerMessage, Message, Target};
 
+#[derive(Default)]
 pub struct Package<'a> {
     pub name: &'a str,
     pub root_dir: &'a str,
+    pub no_default_features: bool,
+    pub features: &'a [&'a str],
 }
 
 fn target_arch_fixup(target_arch: Cow<'_, str>) -> Cow<'_, str> {
@@ -62,7 +65,13 @@ pub fn build_ebpf<'a>(
     let bpf_target_arch = target_arch_fixup(bpf_target_arch.into());
     let target = format!("{target}-unknown-none");
 
-    for Package { name, root_dir } in packages {
+    for Package {
+        name,
+        root_dir,
+        no_default_features,
+        features,
+    } in packages
+    {
         // We have a build-dependency on `name`, so cargo will automatically rebuild us if `name`'s
         // *library* target or any of its dependencies change. Since we depend on `name`'s *binary*
         // targets, that only gets us half of the way. This stanza ensures cargo will rebuild us on
@@ -85,6 +94,10 @@ pub fn build_ebpf<'a>(
             "--target",
             &target,
         ]);
+        if no_default_features {
+            cmd.arg("--no-default-features");
+        }
+        cmd.args(["--features", &features.join(",")]);
 
         {
             const SEPARATOR: &str = "\x1f";

test/integration-test/build.rs

@@ -219,6 +219,7 @@ fn main() -> Result<()> {
                 .parent()
                 .ok_or_else(|| anyhow!("no parent for {manifest_path}"))?
                 .as_str(),
+            ..Default::default()
         };
         aya_build::build_ebpf([integration_ebpf_package], aya_build::Toolchain::default())?;
     } else {

xtask/public-api/aya-build.txt

@@ -27,8 +27,12 @@ pub fn aya_build::Toolchain<'a>::borrow_mut(&mut self) -> &mut T
 impl<T> core::convert::From<T> for aya_build::Toolchain<'a>
 pub fn aya_build::Toolchain<'a>::from(t: T) -> T
 pub struct aya_build::Package<'a>
+pub aya_build::Package::features: &'a [&'a str]
 pub aya_build::Package::name: &'a str
+pub aya_build::Package::no_default_features: bool
 pub aya_build::Package::root_dir: &'a str
+impl<'a> core::default::Default for aya_build::Package<'a>
+pub fn aya_build::Package<'a>::default() -> aya_build::Package<'a>
 impl<'a> core::marker::Freeze for aya_build::Package<'a>
 impl<'a> core::marker::Send for aya_build::Package<'a>
 impl<'a> core::marker::Sync for aya_build::Package<'a>