fix #[hdl]/#[hdl_module] attributes getting the wrong hygiene when processing #[cfg]s

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

@@ -1210,17 +1210,29 @@ fn hdl_main(
     attr: TokenStream,
     item: TokenStream,
 ) -> syn::Result<TokenStream> {
-    let (evaluated_cfgs, attr): (_, TokenStream) = Parser::parse2(
+    fn parse_evaluated_cfgs_attr<R>(
+        input: ParseStream,
+        parse_inner: impl FnOnce(ParseStream) -> syn::Result<R>,
+    ) -> syn::Result<R> {
+        let _: Token![#] = input.parse()?;
+        let bracket_content;
+        bracketed!(bracket_content in input);
+        let _: kw::__evaluated_cfgs = bracket_content.parse()?;
+        let paren_content;
+        parenthesized!(paren_content in bracket_content);
+        parse_inner(&paren_content)
+    }
+    let (evaluated_cfgs, item): (_, 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()?))
+            let peek = input.fork();
+            if parse_evaluated_cfgs_attr(&peek, |_| Ok(())).is_ok() {
+                let evaluated_cfgs = parse_evaluated_cfgs_attr(input, Cfgs::<bool>::parse)?;
+                Ok((Some(evaluated_cfgs), input.parse()?))
             } else {
                 Ok((None, input.parse()?))
             }
         },
-        attr,
+        item,
     )?;
     let cfgs = if let Some(cfgs) = evaluated_cfgs {
         cfgs
@@ -1229,12 +1241,11 @@ fn hdl_main(
         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 }
+                    {#[::fayalite::#kw(#attr)]} { #item }
                 }
             });
         }

crates/fayalite/src/lib.rs

@@ -22,7 +22,8 @@ macro_rules! __cfg_expansion_helper {
             $cfg:ident($($expr:tt)*),
             $($unevaluated_cfgs:ident($($unevaluated_exprs:tt)*),)*
         ]
-        #[$after_evaluation:path:($($after_evaluation_attr_args:tt)*)] {$($after_evaluation_args:tt)*}
+        // pass as tt so we get right span for attribute
+        $after_evaluation_attr:tt $after_evaluation_body:tt
     ) => {
         #[$cfg($($expr)*)]
         $crate::__cfg_expansion_helper! {
@@ -33,7 +34,7 @@ macro_rules! __cfg_expansion_helper {
             [
                 $($unevaluated_cfgs($($unevaluated_exprs)*),)*
             ]
-            #[$after_evaluation:($($after_evaluation_attr_args)*)] {$($after_evaluation_args)*}
+            $after_evaluation_attr $after_evaluation_body
         }
         #[$cfg(not($($expr)*))]
         $crate::__cfg_expansion_helper! {
@@ -44,7 +45,7 @@ macro_rules! __cfg_expansion_helper {
             [
                 $($unevaluated_cfgs($($unevaluated_exprs)*),)*
             ]
-            #[$after_evaluation:($($after_evaluation_attr_args)*)] {$($after_evaluation_args)*}
+            $after_evaluation_attr $after_evaluation_body
         }
     };
     (
@@ -52,12 +53,14 @@ macro_rules! __cfg_expansion_helper {
             $($evaluated_cfgs:ident($($evaluated_exprs:tt)*) = $evaluated_results:ident,)*
         ]
         []
-        #[$after_evaluation:path:($($after_evaluation_attr_args:tt)*)] {$($after_evaluation_args:tt)*}
+        // don't use #[...] so we get right span for `#` and `[]` of attribute
+        {$($after_evaluation_attr:tt)*} {$($after_evaluation_body:tt)*}
     ) => {
-        #[$after_evaluation([
+        $($after_evaluation_attr)*
+        #[__evaluated_cfgs([
             $($evaluated_cfgs($($evaluated_exprs)*) = $evaluated_results,)*
-        ] $($after_evaluation_attr_args)*)]
-        $($after_evaluation_args)*
+        ])]
+        $($after_evaluation_body)*
     };
 }
 

crates/fayalite/tests/module.rs

@@ -4288,7 +4288,8 @@ circuit check_deduce_resets:
     };
 }
 
-#[hdl_module(outline_generated)]
+// intentionally not outline_generated to ensure we get correct macro hygiene
+#[hdl_module]
 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,
@@ -4335,12 +4336,12 @@ fn test_cfgs() {
         "/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]
+    module check_cfgs: @[the_test_file.rs 9962:1]
+        input i_b: UInt<8> @[the_test_file.rs 9979:20]
+        output o_b: UInt<8> @[the_test_file.rs 9992:24]
+        wire w: Ty0 @[the_test_file.rs 9981:25]
+        connect o_b, w.b @[the_test_file.rs 9993:9]
+        connect w.b, i_b @[the_test_file.rs 9994:9]
 ",
     };
 }