validate macro input at entry point

bilge-impl/src/bitsize.rs

@@ -13,8 +13,8 @@ struct ItemIr {
     expanded: TokenStream,
 }
 
-pub(super) fn bitsize(args: TokenStream, item: TokenStream) -> TokenStream {
-    let (item, declared_bitsize) = parse(item, args);
+pub(super) fn bitsize(args: TokenStream, item: Item) -> TokenStream {
+    let (declared_bitsize, _arb_int) = shared::bitsize_and_arbitrary_int_from(args);
     let attrs = SplitAttributes::from_item(&item);
     let ir = match item {
         Item::Struct(mut item) => {
@@ -33,17 +33,6 @@ pub(super) fn bitsize(args: TokenStream, item: TokenStream) -> TokenStream {
     generate_common(ir, attrs, declared_bitsize)
 }
 
-fn parse(item: TokenStream, args: TokenStream) -> (Item, BitSize) {
-    let item = syn::parse2(item).unwrap_or_else(unreachable);
-
-    if args.is_empty() {
-        abort_call_site!("missing attribute value"; help = "you need to define the size like this: `#[bitsize(32)]`")
-    }
-
-    let (declared_bitsize, _arb_int) = shared::bitsize_and_arbitrary_int_from(args);
-    (item, declared_bitsize)
-}
-
 fn check_type_is_supported(ty: &Type) {
     use Type::*;
     match ty {

bilge-impl/src/fmt_bits.rs

@@ -3,8 +3,7 @@ use proc_macro2::{Ident, TokenStream};
 use quote::quote;
 use syn::{Data, DeriveInput, Fields, Variant, punctuated::Iter};
 
-pub(crate) fn binary(item: TokenStream) -> TokenStream {
-    let derive_input = parse(item);
+pub(crate) fn binary(derive_input: DeriveInput) -> TokenStream {
     let (derive_data, arb_int, name, bitsize, ..) = analyze(&derive_input);
 
     match derive_data {
@@ -86,10 +85,6 @@ fn generate_to_int_match_arms(variants: Iter<Variant>, enum_name: &Ident, bitsiz
         .collect()
 }
 
-fn parse(item: TokenStream) -> DeriveInput {
-    shared::parse_derive(item)
-}
-
 fn analyze(derive_input: &DeriveInput) -> (&Data, TokenStream, &Ident, BitSize, Option<Fallback>) {
     shared::analyze_derive(derive_input, false)
 }

bilge-impl/src/from_bits.rs

@@ -5,8 +5,7 @@ use quote::quote;
 use syn::{Type, Fields, DeriveInput, Data, punctuated::Iter, Variant};
 use crate::shared::{fallback::Fallback, self, BitSize, unreachable, discriminant_assigner::DiscriminantAssigner, enum_fills_bitsize};
 
-pub(super) fn from_bits(item: TokenStream) -> TokenStream {
-    let derive_input = parse(item);
+pub(super) fn from_bits(derive_input: DeriveInput) -> TokenStream {
     let (derive_data, arb_int, name, internal_bitsize, fallback) = analyze(&derive_input);
     let expanded = match &derive_data {
         Data::Struct(struct_data) => {
@@ -22,10 +21,6 @@ pub(super) fn from_bits(item: TokenStream) -> TokenStream {
     generate_common(expanded)
 }
 
-fn parse(item: TokenStream) -> DeriveInput {
-    shared::parse_derive(item)
-}
-
 fn analyze(derive_input: &DeriveInput) -> (&syn::Data, TokenStream, &Ident, BitSize, Option<Fallback>) {
     shared::analyze_derive(derive_input, false)
 }

bilge-impl/src/lib.rs

@@ -1,5 +1,6 @@
 use proc_macro::TokenStream;
 use proc_macro_error::proc_macro_error;
+use syn::parse_macro_input;
 
 mod bitsize;
 mod bitsize_internal;
@@ -19,15 +20,19 @@ mod shared;
 #[proc_macro_error]
 #[proc_macro_attribute]
 pub fn bitsize(args: TokenStream, item: TokenStream) -> TokenStream {
-    bitsize::bitsize(args.into(), item.into()).into()
+    let item = parse_macro_input!(item);
+
+    bitsize::bitsize(args.into(), item).into()
 }
 
 /// This is internally used, not to be used by anything besides `bitsize`.
 /// No guarantees are given.
 #[proc_macro_error]
 #[proc_macro_attribute]
 pub fn bitsize_internal(args: TokenStream, item: TokenStream) -> TokenStream {
-    bitsize_internal::bitsize_internal(args.into(), item.into()).into()
+    let item = parse_macro_input!(item);
+
+    bitsize_internal::bitsize_internal(args.into(), item).into()
 }
 
 /// Generate an `impl TryFrom<uN>` for unfilled bitfields.
@@ -36,8 +41,10 @@ pub fn bitsize_internal(args: TokenStream, item: TokenStream) -> TokenStream {
 /// a struct don't fill their given `bitsize`.
 #[proc_macro_error]
 #[proc_macro_derive(TryFromBits, attributes(bitsize_internal, fallback))]
-pub fn derive_try_from_bits(item: TokenStream) -> TokenStream {
-    try_from_bits::try_from_bits(item.into()).into()
+pub fn derive_try_from_bits(derive_input: TokenStream) -> TokenStream {
+    let derive_input = parse_macro_input!(derive_input);
+
+    try_from_bits::try_from_bits(derive_input).into()
 }
 
 /// Generate an `impl From<uN>` for filled bitfields.
@@ -47,22 +54,28 @@ pub fn derive_try_from_bits(item: TokenStream) -> TokenStream {
 /// using enums.
 #[proc_macro_error]
 #[proc_macro_derive(FromBits, attributes(bitsize_internal, fallback))]
-pub fn derive_from_bits(item: TokenStream) -> TokenStream {
-    from_bits::from_bits(item.into()).into()
+pub fn derive_from_bits(derive_input: TokenStream) -> TokenStream {
+    let derive_input = parse_macro_input!(derive_input);
+
+    from_bits::from_bits(derive_input).into()
 }
 
 /// Generate an `impl Debug` for bitfield structs.
 /// 
 /// Please use normal #[derive(Debug)] for enums.
 #[proc_macro_error]
 #[proc_macro_derive(DebugBits, attributes(bitsize_internal))]
-pub fn debug_bits(item: TokenStream) -> TokenStream {
-    debug_bits::debug_bits(item.into()).into()
+pub fn debug_bits(derive_input: TokenStream) -> TokenStream {
+    let derive_input = parse_macro_input!(derive_input);
+
+    debug_bits::debug_bits(derive_input).into()
 }
 
 /// Generate an `impl core::fmt::Binary` for bitfields.
 #[proc_macro_error]
 #[proc_macro_derive(BinaryBits)]
-pub fn derive_binary_bits(item: TokenStream) -> TokenStream {
-    fmt_bits::binary(item.into()).into()
+pub fn derive_binary_bits(derive_input: TokenStream) -> TokenStream {
+    let derive_input = parse_macro_input!(derive_input);
+
+    fmt_bits::binary(derive_input).into()
 }

bilge-impl/src/shared.rs

@@ -67,6 +67,10 @@ pub(crate) fn analyze_derive(derive_input: &DeriveInput, try_from: bool) -> (&sy
 
 // If we want to support bitsize(u4) besides bitsize(4), do that here.
 pub fn bitsize_and_arbitrary_int_from(bitsize_arg: TokenStream) -> (BitSize, TokenStream) {
+    if bitsize_arg.is_empty() {
+        abort_call_site!("missing attribute value"; help = "you need to define the size like this: `#[bitsize(32)]`")
+    }
+
     let bitsize: LitInt = syn::parse2(bitsize_arg.clone()).unwrap_or_else(|_|
         abort!(bitsize_arg, "attribute value is not a number"; help = "you need to define the size like this: `#[bitsize(32)]`")
     );

bilge-impl/src/try_from_bits.rs

@@ -5,8 +5,7 @@ use syn::{DeriveInput, Data, punctuated::Iter, Variant, Type, Fields};
 use crate::shared::{last_ident_of_path, bitsize_from_type_ident};
 use crate::shared::{fallback::Fallback, self, BitSize, unreachable, enum_fills_bitsize, discriminant_assigner::DiscriminantAssigner};
 
-pub(super) fn try_from_bits(item: TokenStream) -> TokenStream {
-    let derive_input = parse(item);
+pub(super) fn try_from_bits(derive_input: DeriveInput) -> TokenStream {
     let (derive_data, arb_int, name, internal_bitsize, ..) = analyze(&derive_input);
     match derive_data {
         Data::Struct(ref data) => {
@@ -21,10 +20,6 @@ pub(super) fn try_from_bits(item: TokenStream) -> TokenStream {
     }
 }
 
-fn parse(item: TokenStream) -> DeriveInput {
-    shared::parse_derive(item)
-}
-
 fn analyze(derive_input: &DeriveInput) -> (&syn::Data, TokenStream, &Ident, BitSize, Option<Fallback>) {
     shared::analyze_derive(derive_input, true)
 }