Remove dependency on num_enum.

[rbartlensky]

Hello!

I am using libbpf-rs in one of my personal projects and I noticed that I was pulling in toml-edit via libbpf-rs which accounted for 1.3 seconds of my total build time. With the help of cargo tree I realized that num_enum is pulling in that dependency (and many others!) and I decided to try to remove it from libbpf-rs completely. Let me know what you think!

cargo udeps also noticed some extra things that can be removed, so I went ahead and removed those.

[danielocfb]

Thanks for the proposal! I am in favor of removing these dependencies, I am just not sure about the current implementation hardcoding the values. Can we instead rely on the symbolic values, ala:

--- libbpf-rs/src/btf/mod.rs
+++ libbpf-rs/src/btf/mod.rs
@@ -96,7 +96,7 @@ impl TryFrom<u32> for BtfKind {
         use BtfKind::*;

         Ok(match value {
-            0 => Void,
+            x if x == Void as u32 => Void,

[danielocfb]

Can we remove this case? What purpose does it serve?

[rbartlensky]

consistency with the "old" implementation, but to be fair it's useless, so I removed it

[rbartlensky]

Thanks for the proposal! I am in favor of removing these dependencies, I am just not sure about the current implementation hardcoding the values. Can we instead rely on the symbolic values, ala:

--- libbpf-rs/src/btf/mod.rs
+++ libbpf-rs/src/btf/mod.rs
@@ -96,7 +96,7 @@ impl TryFrom<u32> for BtfKind {
         use BtfKind::*;

         Ok(match value {
-            0 => Void,
+            x if x == Void as u32 => Void,

I think that's even better! I made the changes suggested.

[rbartlensky]

@danielocfb Thank you for taking the time to review! When you're happy with the PR I will squash the fixups away.

[danielocfb]

The changes look great now! Feel free to squash and we can go ahead with the merge. Thanks!

[rbartlensky]

The changes look great now! Feel free to squash and we can go ahead with the merge. Thanks!

Squashed, and ready to go -- thank you!