[breaking change] Add no_std support for tls_codec_derive

.github/workflows/tls_codec.yml

@@ -36,7 +36,7 @@ jobs:
           toolchain: ${{ matrix.rust }}
           targets: ${{ matrix.target }}
       - uses: RustCrypto/actions/cargo-hack-install@master
-      - run: cargo hack build --target ${{ matrix.target }} --feature-powerset --exclude-features std,default,derive,serde,arbitrary
+      - run: cargo hack build --target ${{ matrix.target }} --feature-powerset --exclude-features std,default,serde,arbitrary
 
   minimal-versions:
     uses: RustCrypto/actions/.github/workflows/minimal-versions.yml@master
@@ -70,4 +70,4 @@ jobs:
       - run: ${{ matrix.deps }}
       - uses: RustCrypto/actions/cargo-hack-install@master
       - run: cargo hack test --feature-powerset
-      - run: cargo hack test -p tls_codec_derive --test encode\* --test decode\*
+      - run: cargo hack test -p tls_codec_derive --feature-powerset --test encode\* --test decode\*

tls_codec/Cargo.toml

@@ -28,10 +28,10 @@ regex = "1.8"
 [features]
 default = [ "std" ]
 arbitrary = [ "std", "dep:arbitrary" ]
-derive = [ "std", "tls_codec_derive" ]
+derive = [ "tls_codec_derive" ]
 serde = [ "std", "dep:serde" ]
 mls = [] # In MLS variable length vectors are limited compared to QUIC.
-std = []
+std = [ "tls_codec_derive?/std" ]
 
 [[bench]]
 name = "tls_vec"

tls_codec/derive/Cargo.toml

@@ -21,3 +21,7 @@ proc-macro2 = "1.0"
 [dev-dependencies]
 tls_codec = { path = "../" }
 trybuild = "1"
+
+[features]
+default = [ "std" ]
+std = []

tls_codec/derive/src/lib.rs

@@ -698,7 +698,7 @@ fn impl_tls_size(parsed_ast: TlsStruct) -> TokenStream2 {
                         let field_len = match self {
                             #(#field_arms)*
                         };
-                        std::mem::size_of::<#repr>() + field_len
+                        core::mem::size_of::<#repr>() + field_len
                     }
                 }
 
@@ -740,6 +740,7 @@ fn impl_serialize(parsed_ast: TlsStruct, svariant: SerializeVariant) -> TokenStr
                 SerializeVariant::Write => {
                     quote! {
                         impl #impl_generics tls_codec::Serialize for #ident #ty_generics #where_clause {
+                            #[cfg(feature = "std")]
                             fn tls_serialize<W: std::io::Write>(&self, writer: &mut W) -> core::result::Result<usize, tls_codec::Error> {
                                 let mut written = 0usize;
                                 #(
@@ -760,6 +761,7 @@ fn impl_serialize(parsed_ast: TlsStruct, svariant: SerializeVariant) -> TokenStr
                         }
 
                         impl #impl_generics tls_codec::Serialize for &#ident #ty_generics #where_clause {
+                            #[cfg(feature = "std")]
                             fn tls_serialize<W: std::io::Write>(&self, writer: &mut W) -> core::result::Result<usize, tls_codec::Error> {
                                 tls_codec::Serialize::tls_serialize(*self, writer)
                             }
@@ -850,6 +852,7 @@ fn impl_serialize(parsed_ast: TlsStruct, svariant: SerializeVariant) -> TokenStr
                 SerializeVariant::Write => {
                     quote! {
                         impl #impl_generics tls_codec::Serialize for #ident #ty_generics #where_clause {
+                            #[cfg(feature = "std")]
                             fn tls_serialize<W: std::io::Write>(&self, writer: &mut W) -> core::result::Result<usize, tls_codec::Error> {
                                 #discriminant_constants
                                 match self {
@@ -859,6 +862,7 @@ fn impl_serialize(parsed_ast: TlsStruct, svariant: SerializeVariant) -> TokenStr
                         }
 
                         impl #impl_generics tls_codec::Serialize for &#ident #ty_generics #where_clause {
+                            #[cfg(feature = "std")]
                             fn tls_serialize<W: std::io::Write>(&self, writer: &mut W) -> core::result::Result<usize, tls_codec::Error> {
                                 tls_codec::Serialize::tls_serialize(*self, writer)
                             }
@@ -909,6 +913,7 @@ fn impl_deserialize(parsed_ast: TlsStruct) -> TokenStream2 {
             let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
             quote! {
                 impl #impl_generics tls_codec::Deserialize for #ident #ty_generics #where_clause {
+                    #[cfg(feature = "std")]
                     fn tls_deserialize<R: std::io::Read>(bytes: &mut R) -> core::result::Result<Self, tls_codec::Error> {
                         Ok(Self {
                             #(#members: #prefixes::tls_deserialize(bytes)?,)*
@@ -948,6 +953,7 @@ fn impl_deserialize(parsed_ast: TlsStruct) -> TokenStream2 {
             quote! {
                 impl #impl_generics tls_codec::Deserialize for #ident #ty_generics #where_clause {
                     #[allow(non_upper_case_globals)]
+                    #[cfg(feature = "std")]
                     fn tls_deserialize<R: std::io::Read>(bytes: &mut R) -> core::result::Result<Self, tls_codec::Error> {
                         #discriminant_constants
                         let discriminant = <#repr as tls_codec::Deserialize>::tls_deserialize(bytes)?;

tls_codec/derive/tests/decode.rs

@@ -1,3 +1,4 @@
+#![cfg(feature = "std")]
 use tls_codec::{
     Deserialize, Error, Serialize, Size, TlsSliceU16, TlsVecU16, TlsVecU32, TlsVecU8, VLBytes,
 };