Cleaned up a lot of config specific code

In a number of places we were using `cfg(not(...))` or `cfg(all(...))`
like code, which was not required. The features `python-bindings` and
`wasm` are mutually exclusive and that is checked once already, at all
other places those checks made this look ugly.

Signed-off-by: Abhijit Gadgil <gabhijit@iitbombay.org>

Cargo.toml

@@ -20,12 +20,11 @@ serde_json = { version = "1.0" }
 erased-serde = "0.4"
 log =  { version = "0.4", optional = true }
 
-[target.'cfg(target_family = "wasm")'.dependencies]
-wasm-bindgen = { version = "0.2", optional=true}
+# Required for feature - python-bindings
+pyo3 = { version = "0.20", features = ["extension-module"], optional = true}
 
-
-[target.'cfg(not(target_family = "wasm"))'.dependencies]
-pyo3 = { version = "0.20", features = ["extension-module"], optional=true}
+# Required for feature - wasm
+wasm-bindgen = { version = "0.2" , optional = true}
 
 [dev-dependencies]
 clap = { version = "4.0" , features = ["derive"] }
@@ -34,8 +33,8 @@ clap = { version = "4.0" , features = ["derive"] }
 pcap = { version = "1.3"}
 criterion = "0.5"
 
-[target.'cfg(target_family = "wasm")'.dev-dependencies]
-wasm-bindgen-test = { version = "0.3"}
+[target.'cfg(target_family= "wasm")'.dev-dependencies]
+wasm-bindgen-test = { version = "0.3" }
 
 # Required by `cargo flamegraph`
 [profile.bench]
@@ -75,5 +74,4 @@ walkdir = "2"
 python-bindings = ['pyo3']
 logging = ["log"]
 sculpting = []
-
 wasm = ['wasm-bindgen']

src/errors.rs

@@ -30,7 +30,7 @@ impl core::fmt::Display for Error {
 }
 
 // Python Bindings
-#[cfg(all(feature = "python-bindings", not(target_family = "wasm")))]
+#[cfg(feature = "python-bindings")]
 impl std::convert::From<Error> for pyo3::PyErr {
     // TODO: Add proper error reporting
     fn from(_e: Error) -> pyo3::PyErr {

src/lib.rs

@@ -43,11 +43,12 @@ compile_error!(
     "feature \"python-bindings\" and feature \"wasm\" cannot be enabled at the same time"
 );
 
-#[cfg(all(target_arch = "wasm32", not(feature = "wasm")))]
+#[cfg(all(target_family = "wasm", not(feature = "wasm")))]
 compile_error!("feature \"wasm\" is required for \"wasm32\" targets.");
 
-#[cfg(all(not(target_arch = "wasm32"), feature = "wasm"))]
+/* #[cfg(all(not(target_family = "wasm"), feature = "wasm"))]
 compile_error!("feature \"wasm\" is only supported for \"wasm32\" targets.");
+*/
 
 #[cfg(all(target_family = "wasm", feature = "python-bindings"))]
 compile_error!("feature \"python-bindings\" is not supported for \"wasm32\" targets.");
@@ -76,21 +77,21 @@ pub use packet::Packet;
 #[doc(inline)]
 pub use types::{ENCAP_TYPE_ETH, ENCAP_TYPE_LINUX_SLL, ENCAP_TYPE_LINUX_SLL2};
 
-#[cfg(all(feature = "python-bindings", not(target_family = "wasm")))]
+#[cfg(feature = "python-bindings")]
 use pyo3::prelude::*;
 
 /// Python bindings for packet dissection and sculpting in Rust (scalpel)
-#[cfg(all(feature = "python-bindings", not(target_family = "wasm")))]
+#[cfg(feature = "python-bindings")]
 #[pymodule]
 fn scalpel(py: Python, m: &PyModule) -> PyResult<()> {
     packet::register(py, m)?;
     Ok(())
 }
 
-#[cfg(all(not(feature = "python-bindings"), target_family = "wasm"))]
+#[cfg(feature = "wasm")]
 use wasm_bindgen::prelude::*;
 
-#[cfg(all(not(feature = "python-bindings"), target_family = "wasm"))]
+#[cfg(feature = "wasm")]
 #[wasm_bindgen]
 pub fn dissect_packet(packet: String) -> String {
     let _ = layers::register_defaults();

src/packet.rs

@@ -12,7 +12,7 @@ use crate::errors::Error;
 use crate::types::{EncapType, LayerCreatorFn};
 use crate::Layer;
 
-#[cfg(all(feature = "python-bindings", not(target_family = "wasm")))]
+#[cfg(feature = "python-bindings")]
 use pyo3::prelude::*;
 
 fn get_encap_types_map() -> &'static RwLock<HashMap<EncapType, LayerCreatorFn>> {
@@ -44,7 +44,7 @@ pub(crate) fn register_defaults() -> Result<(), Error> {
 ///              Each of the following is a Layer - `Ethernet`, `IPv4`, `TCP` etc.
 ///  * `unprocessed`: The part of the original byte-stream that is not processed and captured into
 ///                   `layers` above.
-#[cfg_attr(all(feature = "python-bindings", not(target_family = "wasm")), pyclass)]
+#[cfg_attr(feature = "python-bindings", pyclass)]
 #[derive(Debug, Default, Serialize)]
 pub struct Packet {
     pub meta: PacketMetadata,
@@ -177,7 +177,7 @@ impl Packet {
 
 // Python Bindings
 #[allow(clippy::borrow_deref_ref)]
-#[cfg(all(feature = "python-bindings", not(target_family = "wasm")))]
+#[cfg(feature = "python-bindings")]
 #[pymethods]
 impl Packet {
     #[staticmethod]
@@ -192,7 +192,7 @@ impl Packet {
     }
 }
 
-#[cfg(all(feature = "python-bindings", not(target_family = "wasm")))]
+#[cfg(feature = "python-bindings")]
 pub(crate) fn register(_py: Python, m: &PyModule) -> PyResult<()> {
     m.add_class::<Packet>()?;
     Ok(())