Add bits as an optional feature for bitvec (#446)

* Make bitvec completely optional

* Add bits feature to bench

* Add docs

* Add bits to ensure_no_std features

* Add bits feature to deku-derive

* Use bits feature to correctly disallow bit related attributes from being
  used

Author: wcampbell0x2a

.github/workflows/main.yml

@@ -22,6 +22,8 @@ jobs:
       - run: cargo test --all
       # run examples
       - run: cargo run --example 2>&1 | grep -P '   ' | awk '{print $1}' | xargs -i cargo run --example {}
+      # test with no bits feature (don't test docs)
+      - run: cargo test --lib --examples --tests --features std --no-default-features
 
   # Only build on MSRV, since trybuild will fail on older version
   build-msrv:

Cargo.toml

@@ -20,16 +20,17 @@ members = [
 ]
 
 [features]
-default = ["std"]
-std = ["deku_derive/std", "bitvec/std", "alloc", "no_std_io/std"]
-alloc = ["bitvec/alloc"]
+default = ["std", "bits"]
+std = ["deku_derive/std", "bitvec?/std", "alloc", "no_std_io/std"]
+alloc = ["bitvec?/alloc"]
 logging = ["deku_derive/logging", "log"]
 no-assert-string = ["deku_derive/no-assert-string"]
 error_in_core = []
+bits = ["dep:bitvec", "deku_derive/bits"]
 
 [dependencies]
 deku_derive = { version = "^0.17.0", path = "deku-derive", default-features = false}
-bitvec = { version = "1.0.1", default-features = false }
+bitvec = { version = "1.0.1", default-features = false, optional = true }
 log = { version = "0.4.21", optional = true }
 no_std_io = { version = "0.8.0", default-features = false, features = ["alloc"], package = "no_std_io2" }
 rustversion = "1.0.16"
@@ -55,3 +56,31 @@ workspace = true
 # Triggers in macro generated code of darling
 # https://github.com/rust-lang/rust-clippy/issues/12643
 manual-unwrap-or-default = "allow"
+
+[[example]]
+name = "custom_reader_and_writer"
+required-features = ["bits"]
+
+[[example]]
+name = "deku_input"
+
+[[example]]
+name = "enums_catch_all"
+required-features = ["bits"]
+
+[[example]]
+name = "enums"
+
+[[example]]
+name = "example"
+required-features = ["bits"]
+
+[[example]]
+name = "ipv4"
+required-features = ["bits"]
+
+[[example]]
+name = "many"
+
+[[example]]
+name = "read_all"

benches/deku.rs

@@ -3,6 +3,7 @@ use std::io::{Cursor, Read, Seek};
 use criterion::{black_box, criterion_group, criterion_main, BatchSize, Criterion};
 use deku::prelude::*;
 
+#[cfg(feature = "bits")]
 #[derive(Debug, PartialEq, DekuRead, DekuWrite)]
 struct DekuBits {
     #[deku(bits = 1)]
@@ -61,6 +62,7 @@ fn criterion_benchmark(c: &mut Criterion) {
             }))
         })
     });
+    #[cfg(feature = "bits")]
     c.bench_function("deku_read_bits", |b| {
         let reader = Cursor::new(&[0x01; 1]);
         b.iter_batched(
@@ -69,6 +71,7 @@ fn criterion_benchmark(c: &mut Criterion) {
             BatchSize::SmallInput,
         )
     });
+    #[cfg(feature = "bits")]
     c.bench_function("deku_write_bits", |b| {
         b.iter(|| {
             deku_write(black_box(&DekuBits {

deku-derive/Cargo.toml

@@ -16,6 +16,7 @@ proc-macro = true
 std = ["proc-macro-crate"]
 logging = []
 no-assert-string = []
+bits = []
 
 [dependencies]
 quote = "1.0"

deku-derive/src/lib.rs

@@ -136,6 +136,7 @@ struct DekuData {
     id_type: Option<TokenStream>,
 
     /// enum only: bit size of the enum `id`
+    #[cfg(feature = "bits")]
     bits: Option<Num>,
 
     /// enum only: byte size of the enum `id`
@@ -198,6 +199,7 @@ impl DekuData {
             magic: receiver.magic,
             id: receiver.id,
             id_type: receiver.id_type?,
+            #[cfg(feature = "bits")]
             bits: receiver.bits,
             bytes: receiver.bytes,
             seek_rewind: receiver.seek_rewind,
@@ -224,7 +226,7 @@ impl DekuData {
         match data.data {
             ast::Data::Struct(_) => {
                 // Validate id_* attributes are being used on an enum
-                if data.id_type.is_some() {
+                let ret = if data.id_type.is_some() {
                     Err(cerror(
                         data.id_type.span(),
                         "`id_type` only supported on enum",
@@ -233,11 +235,16 @@ impl DekuData {
                     Err(cerror(data.id.span(), "`id` only supported on enum"))
                 } else if data.bytes.is_some() {
                     Err(cerror(data.bytes.span(), "`bytes` only supported on enum"))
-                } else if data.bits.is_some() {
-                    Err(cerror(data.bits.span(), "`bits` only supported on enum"))
                 } else {
                     Ok(())
+                };
+
+                #[cfg(feature = "bits")]
+                if ret.is_ok() && data.bits.is_some() {
+                    return Err(cerror(data.bits.span(), "`bits` only supported on enum"));
                 }
+
+                ret
             }
             ast::Data::Enum(_) => {
                 // Validate `id_type` or `id` is specified
@@ -257,6 +264,7 @@ impl DekuData {
                 }
 
                 // Validate `id_*` used correctly
+                #[cfg(feature = "bits")]
                 if data.id.is_some() && data.bits.is_some() {
                     return Err(cerror(
                         data.ident.span(),
@@ -271,6 +279,7 @@ impl DekuData {
                 }
 
                 // Validate either `bits` or `bytes` is specified
+                #[cfg(feature = "bits")]
                 if data.bits.is_some() && data.bytes.is_some() {
                     return Err(cerror(
                         data.bits.span(),
@@ -336,7 +345,10 @@ impl<'a> TryFrom<&'a DekuData> for DekuDataEnum<'a> {
 
         let id_args = crate::macros::gen_id_args(
             deku_data.endian.as_ref(),
+            #[cfg(feature = "bits")]
             deku_data.bits.as_ref(),
+            #[cfg(not(feature = "bits"))]
+            None,
             deku_data.bytes.as_ref(),
         )?;
 
@@ -393,6 +405,7 @@ struct FieldData {
     endian: Option<syn::LitStr>,
 
     /// field bit size
+    #[cfg(feature = "bits")]
     bits: Option<Num>,
 
     /// field byte size
@@ -402,6 +415,7 @@ struct FieldData {
     count: Option<TokenStream>,
 
     /// tokens providing the number of bits for the length of the container
+    #[cfg(feature = "bits")]
     bits_read: Option<TokenStream>,
 
     /// tokens providing the number of bytes for the length of the container
@@ -432,12 +446,14 @@ struct FieldData {
     skip: bool,
 
     /// pad a number of bits before
+    #[cfg(feature = "bits")]
     pad_bits_before: Option<TokenStream>,
 
     /// pad a number of bytes before
     pad_bytes_before: Option<TokenStream>,
 
     /// pad a number of bits after
+    #[cfg(feature = "bits")]
     pad_bits_after: Option<TokenStream>,
 
     /// pad a number of bytes after
@@ -486,9 +502,11 @@ impl FieldData {
             ident: receiver.ident,
             ty: receiver.ty,
             endian: receiver.endian,
+            #[cfg(feature = "bits")]
             bits: receiver.bits,
             bytes: receiver.bytes,
             count: receiver.count?,
+            #[cfg(feature = "bits")]
             bits_read: receiver.bits_read?,
             bytes_read: receiver.bytes_read?,
             until: receiver.until?,
@@ -499,8 +517,10 @@ impl FieldData {
             reader: receiver.reader?,
             writer: receiver.writer?,
             skip: receiver.skip,
+            #[cfg(feature = "bits")]
             pad_bits_before: receiver.pad_bits_before?,
             pad_bytes_before: receiver.pad_bytes_before?,
+            #[cfg(feature = "bits")]
             pad_bits_after: receiver.pad_bits_after?,
             pad_bytes_after: receiver.pad_bytes_after?,
             temp: receiver.temp,
@@ -524,6 +544,7 @@ impl FieldData {
 
     fn validate(data: &FieldData) -> Result<(), TokenStream> {
         // Validate either `read_bytes` or `read_bits` is specified
+        #[cfg(feature = "bits")]
         if data.bits_read.is_some() && data.bytes_read.is_some() {
             return Err(cerror(
                 data.bits_read.span(),
@@ -532,6 +553,7 @@ impl FieldData {
         }
 
         // Validate either `count` or `bits_read`/`bytes_read` is specified
+        #[cfg(feature = "bits")]
         if data.count.is_some() && (data.bits_read.is_some() || data.bytes_read.is_some()) {
             if data.bits_read.is_some() {
                 return Err(cerror(
@@ -546,7 +568,16 @@ impl FieldData {
             }
         }
 
+        #[cfg(not(feature = "bits"))]
+        if data.count.is_some() && data.bytes_read.is_some() {
+            return Err(cerror(
+                data.count.span(),
+                "conflicting: both `count` and `bytes_read` specified on field",
+            ));
+        }
+
         // Validate either `bits` or `bytes` is specified
+        #[cfg(feature = "bits")]
         if data.bits.is_some() && data.bytes.is_some() {
             // FIXME: Use `Span::join` once out of nightly
             return Err(cerror(
@@ -565,6 +596,7 @@ impl FieldData {
         }
 
         // Validate usage of read_all
+        #[cfg(feature = "bits")]
         if data.read_all
             && (data.until.is_some()
                 || data.count.is_some()
@@ -707,6 +739,7 @@ struct DekuReceiver {
     id_type: Result<Option<TokenStream>, ReplacementError>,
 
     /// enum only: bit size of the enum `id`
+    #[cfg(feature = "bits")]
     #[darling(default)]
     bits: Option<Num>,
 
@@ -816,6 +849,7 @@ struct DekuFieldReceiver {
     endian: Option<syn::LitStr>,
 
     /// field bit size
+    #[cfg(feature = "bits")]
     #[darling(default)]
     bits: Option<Num>,
 
@@ -828,6 +862,7 @@ struct DekuFieldReceiver {
     count: Result<Option<TokenStream>, ReplacementError>,
 
     /// tokens providing the number of bits for the length of the container
+    #[cfg(feature = "bits")]
     #[darling(default = "default_res_opt", map = "map_litstr_as_tokenstream")]
     bits_read: Result<Option<TokenStream>, ReplacementError>,
 
@@ -871,6 +906,7 @@ struct DekuFieldReceiver {
     skip: bool,
 
     /// pad a number of bits before
+    #[cfg(feature = "bits")]
     #[darling(default = "default_res_opt", map = "map_litstr_as_tokenstream")]
     pad_bits_before: Result<Option<TokenStream>, ReplacementError>,
 
@@ -879,6 +915,7 @@ struct DekuFieldReceiver {
     pad_bytes_before: Result<Option<TokenStream>, ReplacementError>,
 
     /// pad a number of bits after
+    #[cfg(feature = "bits")]
     #[darling(default = "default_res_opt", map = "map_litstr_as_tokenstream")]
     pad_bits_after: Result<Option<TokenStream>, ReplacementError>,