Cargo.lock

@@ -543,9 +543,9 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.83"
+version = "1.0.92"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0b33eb56c327dec362a9e55b3ad14f9d2f0904fb5a5b03b513ab5465399e9f43"
+checksum = "37d3544b3f2748c54e147655edb5025752e2303145b5aefb3c3ea2c78b973bb0"
 dependencies = [
  "unicode-ident",
 ]
@@ -647,9 +647,9 @@ checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
 
 [[package]]
 name = "syn"
-version = "2.0.66"
+version = "2.0.93"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c42f3f41a2de00b01c0aaad383c5a45241efc8b2d1eda5661812fda5f3cdcff5"
+checksum = "9c786062daee0d6db1132800e623df74274a0a87322d8e183338e01b3d98d058"
 dependencies = [
  "proc-macro2",
  "quote",

Cargo.toml

@@ -37,7 +37,7 @@ quote = "1.0.36"
 serde = { version = "1.0.202", features = ["derive"] }
 serde_json = { version = "1.0.117", features = ["preserve_order"] }
 sha2 = "0.10.8"
-syn = { version = "2.0.66", features = ["full", "fold", "visit", "extra-traits"] }
+syn = { version = "2.0.93", features = ["full", "fold", "visit", "extra-traits"] }
 tempfile = "3.10.1"
 thiserror = "1.0.61"
 trybuild = "1.0"

crates/fayalite-proc-macros-impl/src/lib.rs

@@ -3,14 +3,20 @@
 #![cfg_attr(test, recursion_limit = "512")]
 use proc_macro2::{Span, TokenStream};
 use quote::{quote, ToTokens};
-use std::io::{ErrorKind, Write};
+use std::{
+    collections::{hash_map::Entry, HashMap},
+    io::{ErrorKind, Write},
+};
 use syn::{
-    bracketed, parenthesized,
+    bracketed,
+    ext::IdentExt,
+    parenthesized,
     parse::{Parse, ParseStream, Parser},
     parse_quote,
-    punctuated::Pair,
+    punctuated::{Pair, Punctuated},
     spanned::Spanned,
-    AttrStyle, Attribute, Error, Item, ItemFn, Token,
+    token::{Bracket, Paren},
+    AttrStyle, Attribute, Error, Ident, Item, ItemFn, LitBool, LitStr, Meta, Token,
 };
 
 mod fold;
@@ -19,6 +25,7 @@ mod hdl_enum;
 mod hdl_type_alias;
 mod hdl_type_common;
 mod module;
+mod process_cfg;
 
 pub(crate) trait CustomToken:
     Copy
@@ -59,6 +66,11 @@ mod kw {
         };
     }
 
+    custom_keyword!(__evaluated_cfgs);
+    custom_keyword!(all);
+    custom_keyword!(any);
+    custom_keyword!(cfg);
+    custom_keyword!(cfg_attr);
     custom_keyword!(clock_domain);
     custom_keyword!(connect_inexact);
     custom_keyword!(custom_bounds);
@@ -75,6 +87,7 @@ mod kw {
     custom_keyword!(no_reset);
     custom_keyword!(no_runtime_generics);
     custom_keyword!(no_static);
+    custom_keyword!(not);
     custom_keyword!(outline_generated);
     custom_keyword!(output);
     custom_keyword!(reg_builder);
@@ -901,15 +914,335 @@ fn hdl_module_impl(item: ItemFn) -> syn::Result<TokenStream> {
     Ok(contents)
 }
 
-pub fn hdl_module(attr: TokenStream, item: TokenStream) -> syn::Result<TokenStream> {
+#[derive(Clone, PartialEq, Eq, Hash, Debug)]
-    let kw = kw::hdl_module::default();
+pub(crate) enum CfgExpr {
-    hdl_module_impl(syn::parse2(quote! { #[#kw(#attr)] #item })?)
+    Option {
+        ident: Ident,
+        value: Option<(Token![=], LitStr)>,
+    },
+    All {
+        all: kw::all,
+        paren: Paren,
+        exprs: Punctuated<CfgExpr, Token![,]>,
+    },
+    Any {
+        any: kw::any,
+        paren: Paren,
+        exprs: Punctuated<CfgExpr, Token![,]>,
+    },
+    Not {
+        not: kw::not,
+        paren: Paren,
+        expr: Box<CfgExpr>,
+        trailing_comma: Option<Token![,]>,
+    },
 }
 
-pub fn hdl_attr(attr: TokenStream, item: TokenStream) -> syn::Result<TokenStream> {
+impl Parse for CfgExpr {
-    let kw = kw::hdl::default();
+    fn parse(input: ParseStream) -> syn::Result<Self> {
-    let item = quote! { #[#kw(#attr)] #item };
+        match input.cursor().ident() {
-    let item = syn::parse2::<Item>(item)?;
+            Some((_, cursor)) if cursor.eof() => {
+                return Ok(CfgExpr::Option {
+                    ident: input.call(Ident::parse_any)?,
+                    value: None,
+                });
+            }
+            _ => {}
+        }
+        if input.peek(Ident::peek_any) && input.peek2(Token![=]) {
+            return Ok(CfgExpr::Option {
+                ident: input.call(Ident::parse_any)?,
+                value: Some((input.parse()?, input.parse()?)),
+            });
+        }
+        let contents;
+        if input.peek(kw::all) {
+            Ok(CfgExpr::All {
+                all: input.parse()?,
+                paren: parenthesized!(contents in input),
+                exprs: contents.call(Punctuated::parse_terminated)?,
+            })
+        } else if input.peek(kw::any) {
+            Ok(CfgExpr::Any {
+                any: input.parse()?,
+                paren: parenthesized!(contents in input),
+                exprs: contents.call(Punctuated::parse_terminated)?,
+            })
+        } else if input.peek(kw::not) {
+            Ok(CfgExpr::Not {
+                not: input.parse()?,
+                paren: parenthesized!(contents in input),
+                expr: contents.parse()?,
+                trailing_comma: contents.parse()?,
+            })
+        } else {
+            Err(input.error("expected cfg-pattern"))
+        }
+    }
+}
+
+impl ToTokens for CfgExpr {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        match self {
+            CfgExpr::Option { ident, value } => {
+                ident.to_tokens(tokens);
+                if let Some((eq, value)) = value {
+                    eq.to_tokens(tokens);
+                    value.to_tokens(tokens);
+                }
+            }
+            CfgExpr::All { all, paren, exprs } => {
+                all.to_tokens(tokens);
+                paren.surround(tokens, |tokens| exprs.to_tokens(tokens));
+            }
+            CfgExpr::Any { any, paren, exprs } => {
+                any.to_tokens(tokens);
+                paren.surround(tokens, |tokens| exprs.to_tokens(tokens));
+            }
+            CfgExpr::Not {
+                not,
+                paren,
+                expr,
+                trailing_comma,
+            } => {
+                not.to_tokens(tokens);
+                paren.surround(tokens, |tokens| {
+                    expr.to_tokens(tokens);
+                    trailing_comma.to_tokens(tokens);
+                });
+            }
+        }
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Hash, Debug)]
+pub(crate) struct Cfg {
+    cfg: kw::cfg,
+    paren: Paren,
+    expr: CfgExpr,
+    trailing_comma: Option<Token![,]>,
+}
+
+impl Cfg {
+    fn parse_meta(meta: &Meta) -> syn::Result<Self> {
+        syn::parse2(meta.to_token_stream())
+    }
+}
+
+impl ToTokens for Cfg {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let Self {
+            cfg,
+            paren,
+            expr,
+            trailing_comma,
+        } = self;
+        cfg.to_tokens(tokens);
+        paren.surround(tokens, |tokens| {
+            expr.to_tokens(tokens);
+            trailing_comma.to_tokens(tokens);
+        });
+    }
+}
+
+impl Parse for Cfg {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let contents;
+        Ok(Self {
+            cfg: input.parse()?,
+            paren: parenthesized!(contents in input),
+            expr: contents.parse()?,
+            trailing_comma: contents.parse()?,
+        })
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Hash, Debug)]
+pub(crate) struct CfgAttr {
+    cfg_attr: kw::cfg_attr,
+    paren: Paren,
+    expr: CfgExpr,
+    comma: Token![,],
+    attrs: Punctuated<Meta, Token![,]>,
+}
+
+impl CfgAttr {
+    pub(crate) fn to_cfg(&self) -> Cfg {
+        Cfg {
+            cfg: kw::cfg(self.cfg_attr.span),
+            paren: self.paren,
+            expr: self.expr.clone(),
+            trailing_comma: None,
+        }
+    }
+    fn parse_meta(meta: &Meta) -> syn::Result<Self> {
+        syn::parse2(meta.to_token_stream())
+    }
+}
+
+impl Parse for CfgAttr {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let contents;
+        Ok(Self {
+            cfg_attr: input.parse()?,
+            paren: parenthesized!(contents in input),
+            expr: contents.parse()?,
+            comma: contents.parse()?,
+            attrs: contents.call(Punctuated::parse_terminated)?,
+        })
+    }
+}
+
+pub(crate) struct CfgAndValue {
+    cfg: Cfg,
+    eq_token: Token![=],
+    value: LitBool,
+}
+
+impl Parse for CfgAndValue {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        Ok(Self {
+            cfg: input.parse()?,
+            eq_token: input.parse()?,
+            value: input.parse()?,
+        })
+    }
+}
+
+pub(crate) struct Cfgs<T> {
+    pub(crate) bracket: Bracket,
+    pub(crate) cfgs_map: HashMap<Cfg, T>,
+    pub(crate) cfgs_list: Vec<Cfg>,
+}
+
+impl<T> Default for Cfgs<T> {
+    fn default() -> Self {
+        Self {
+            bracket: Default::default(),
+            cfgs_map: Default::default(),
+            cfgs_list: Default::default(),
+        }
+    }
+}
+
+impl<T> Cfgs<T> {
+    fn insert_cfg(&mut self, cfg: Cfg, value: T) {
+        match self.cfgs_map.entry(cfg) {
+            Entry::Occupied(_) => {}
+            Entry::Vacant(entry) => {
+                self.cfgs_list.push(entry.key().clone());
+                entry.insert(value);
+            }
+        }
+    }
+}
+
+impl Parse for Cfgs<bool> {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let contents;
+        let bracket = bracketed!(contents in input);
+        let mut cfgs_map = HashMap::new();
+        let mut cfgs_list = Vec::new();
+        for CfgAndValue {
+            cfg,
+            eq_token,
+            value,
+        } in contents.call(Punctuated::<CfgAndValue, Token![,]>::parse_terminated)?
+        {
+            let _ = eq_token;
+            match cfgs_map.entry(cfg) {
+                Entry::Occupied(_) => {}
+                Entry::Vacant(entry) => {
+                    cfgs_list.push(entry.key().clone());
+                    entry.insert(value.value);
+                }
+            }
+        }
+        Ok(Self {
+            bracket,
+            cfgs_map,
+            cfgs_list,
+        })
+    }
+}
+
+impl Parse for Cfgs<()> {
+    fn parse(input: ParseStream) -> syn::Result<Self> {
+        let contents;
+        let bracket = bracketed!(contents in input);
+        let mut cfgs_map = HashMap::new();
+        let mut cfgs_list = Vec::new();
+        for cfg in contents.call(Punctuated::<Cfg, Token![,]>::parse_terminated)? {
+            match cfgs_map.entry(cfg) {
+                Entry::Occupied(_) => {}
+                Entry::Vacant(entry) => {
+                    cfgs_list.push(entry.key().clone());
+                    entry.insert(());
+                }
+            }
+        }
+        Ok(Self {
+            bracket,
+            cfgs_map,
+            cfgs_list,
+        })
+    }
+}
+
+impl ToTokens for Cfgs<()> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let Self {
+            bracket,
+            cfgs_map: _,
+            cfgs_list,
+        } = self;
+        bracket.surround(tokens, |tokens| {
+            for cfg in cfgs_list {
+                cfg.to_tokens(tokens);
+                <Token![,]>::default().to_tokens(tokens);
+            }
+        });
+    }
+}
+
+fn hdl_main(
+    kw: impl CustomToken,
+    attr: TokenStream,
+    item: TokenStream,
+) -> syn::Result<TokenStream> {
+    let (evaluated_cfgs, attr): (_, TokenStream) = Parser::parse2(
+        |input: ParseStream| {
+            if input.peek(Bracket) && input.peek2(kw::__evaluated_cfgs) {
+                let cfgs = input.parse()?;
+                let _: kw::__evaluated_cfgs = input.parse()?;
+                Ok((Some(cfgs), input.parse()?))
+            } else {
+                Ok((None, input.parse()?))
+            }
+        },
+        attr,
+    )?;
+    let cfgs = if let Some(cfgs) = evaluated_cfgs {
+        cfgs
+    } else {
+        let cfgs = process_cfg::collect_cfgs(syn::parse2(item.clone())?)?;
+        if cfgs.cfgs_list.is_empty() {
+            Cfgs::default()
+        } else {
+            let key = kw::__evaluated_cfgs::default();
+            return Ok(quote! {
+                ::fayalite::__cfg_expansion_helper! {
+                    []
+                    #cfgs
+                    #[::fayalite::#kw:(#key #attr)] { #item }
+                }
+            });
+        }
+    };
+    let item = syn::parse2(quote! { #[#kw(#attr)] #item })?;
+    let Some(item) = process_cfg::process_cfgs(item, cfgs)? else {
+        return Ok(TokenStream::new());
+    };
     match item {
         Item::Enum(item) => hdl_enum::hdl_enum(item),
         Item::Struct(item) => hdl_bundle::hdl_bundle(item),
@@ -921,3 +1254,11 @@ pub fn hdl_attr(attr: TokenStream, item: TokenStream) -> syn::Result<TokenStream
         )),
     }
 }
+
+pub fn hdl_module(attr: TokenStream, item: TokenStream) -> syn::Result<TokenStream> {
+    hdl_main(kw::hdl_module::default(), attr, item)
+}
+
+pub fn hdl_attr(attr: TokenStream, item: TokenStream) -> syn::Result<TokenStream> {
+    hdl_main(kw::hdl::default(), attr, item)
+}

crates/fayalite/build.rs

@@ -5,6 +5,9 @@ use std::{env, fs, path::Path};
 
 fn main() {
     println!("cargo::rustc-check-cfg=cfg(todo)");
+    println!("cargo::rustc-check-cfg=cfg(cfg_false_for_tests)");
+    println!("cargo::rustc-check-cfg=cfg(cfg_true_for_tests)");
+    println!("cargo::rustc-cfg=cfg_true_for_tests");
     let path = "visit_types.json";
     println!("cargo::rerun-if-changed={path}");
     println!("cargo::rerun-if-changed=build.rs");

crates/fayalite/src/lib.rs

@@ -11,6 +11,56 @@ extern crate self as fayalite;
 #[doc(hidden)]
 pub use std as __std;
 
+#[doc(hidden)]
+#[macro_export]
+macro_rules! __cfg_expansion_helper {
+    (
+        [
+            $($evaluated_cfgs:ident($($evaluated_exprs:tt)*) = $evaluated_results:ident,)*
+        ]
+        [
+            $cfg:ident($($expr:tt)*),
+            $($unevaluated_cfgs:ident($($unevaluated_exprs:tt)*),)*
+        ]
+        #[$after_evaluation:path:($($after_evaluation_attr_args:tt)*)] {$($after_evaluation_args:tt)*}
+    ) => {
+        #[$cfg($($expr)*)]
+        $crate::__cfg_expansion_helper! {
+            [
+                $($evaluated_cfgs($($evaluated_exprs)*) = $evaluated_results,)*
+                $cfg($($expr)*) = true,
+            ]
+            [
+                $($unevaluated_cfgs($($unevaluated_exprs)*),)*
+            ]
+            #[$after_evaluation:($($after_evaluation_attr_args)*)] {$($after_evaluation_args)*}
+        }
+        #[$cfg(not($($expr)*))]
+        $crate::__cfg_expansion_helper! {
+            [
+                $($evaluated_cfgs($($evaluated_exprs)*) = $evaluated_results,)*
+                $cfg($($expr)*) = false,
+            ]
+            [
+                $($unevaluated_cfgs($($unevaluated_exprs)*),)*
+            ]
+            #[$after_evaluation:($($after_evaluation_attr_args)*)] {$($after_evaluation_args)*}
+        }
+    };
+    (
+        [
+            $($evaluated_cfgs:ident($($evaluated_exprs:tt)*) = $evaluated_results:ident,)*
+        ]
+        []
+        #[$after_evaluation:path:($($after_evaluation_attr_args:tt)*)] {$($after_evaluation_args:tt)*}
+    ) => {
+        #[$after_evaluation([
+            $($evaluated_cfgs($($evaluated_exprs)*) = $evaluated_results,)*
+        ] $($after_evaluation_attr_args)*)]
+        $($after_evaluation_args)*
+    };
+}
+
 #[doc(inline)]
 /// The `#[hdl_module]` attribute is applied to a Rust function so that that function creates
 /// a [`Module`][`::fayalite::module::Module`] when called.

crates/fayalite/tests/module.rs

@@ -4287,3 +4287,60 @@ circuit check_deduce_resets:
 ",
     };
 }
+
+#[hdl_module(outline_generated)]
+pub fn check_cfgs<#[cfg(cfg_false_for_tests)] A: Type, #[cfg(cfg_true_for_tests)] B: Type>(
+    #[cfg(cfg_false_for_tests)] a: A,
+    #[cfg(cfg_true_for_tests)] b: B,
+) {
+    #[hdl]
+    struct S<#[cfg(cfg_false_for_tests)] A, #[cfg(cfg_true_for_tests)] B> {
+        #[cfg(cfg_false_for_tests)]
+        a: A,
+        #[cfg(cfg_true_for_tests)]
+        b: B,
+    }
+    #[hdl]
+    #[cfg(cfg_false_for_tests)]
+    let i_a: A = m.input(a);
+    #[hdl]
+    #[cfg(cfg_true_for_tests)]
+    let i_b: B = m.input(b);
+    #[hdl]
+    let w: S<UInt<8>> = wire();
+    #[cfg(cfg_false_for_tests)]
+    {
+        #[hdl]
+        let o_a: A = m.output(a);
+        connect(o_a, w.a.cast_bits_to(a));
+        connect_any(w.a, i_a.cast_to_bits());
+    }
+    #[cfg(cfg_true_for_tests)]
+    {
+        #[hdl]
+        let o_b: B = m.output(b);
+        connect(o_b, w.b.cast_bits_to(b));
+        connect_any(w.b, i_b.cast_to_bits());
+    }
+}
+
+#[test]
+fn test_cfgs() {
+    let _n = SourceLocation::normalize_files_for_tests();
+    let m = check_cfgs(UInt[8]);
+    dbg!(m);
+    #[rustfmt::skip] // work around https://github.com/rust-lang/rustfmt/issues/6161
+    assert_export_firrtl! {
+        m =>
+        "/test/check_cfgs.fir": r"FIRRTL version 3.2.0
+circuit check_cfgs:
+    type Ty0 = {b: UInt<8>}
+    module check_cfgs: @[module-XXXXXXXXXX.rs 1:1]
+        input i_b: UInt<8> @[module-XXXXXXXXXX.rs 2:1]
+        output o_b: UInt<8> @[module-XXXXXXXXXX.rs 4:1]
+        wire w: Ty0 @[module-XXXXXXXXXX.rs 3:1]
+        connect o_b, w.b @[module-XXXXXXXXXX.rs 5:1]
+        connect w.b, i_b @[module-XXXXXXXXXX.rs 6:1]
+",
+    };
+}