WIP implementing handling #[cfg] and #[cfg_attr] in proc macro inputs

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

@@ -271,27 +271,60 @@ impl<T: Process<P>, P: Phase> Process<P> for Box<T> {
     }
 }
 
+trait ProcessVecElement {
+    const REMOVE_ELEMENTS: bool;
+}
+
+impl ProcessVecElement for syn::Stmt {
+    const REMOVE_ELEMENTS: bool = true;
+}
+
+impl ProcessVecElement for syn::ForeignItem {
+    const REMOVE_ELEMENTS: bool = true;
+}
+
+impl ProcessVecElement for syn::ImplItem {
+    const REMOVE_ELEMENTS: bool = true;
+}
+
+impl ProcessVecElement for syn::Item {
+    const REMOVE_ELEMENTS: bool = true;
+}
+
+impl ProcessVecElement for syn::TraitItem {
+    const REMOVE_ELEMENTS: bool = true;
+}
+
+impl<T: Process<P> + ProcessVecElement, P: Phase> Process<P> for Vec<T> {
+    fn process(self, state: &mut State<P>) -> Option<Output<Self, P>> {
+        let mut output = Output::new(Vec::new());
+        for value in self {
+            if let Some(value) = value.process(state) {
+                output = (output, value).call(|(mut output, value)| {
+                    output.push(value);
+                    output
+                });
+            } else if !T::REMOVE_ELEMENTS {
+                return None;
+            }
+        }
+        Some(output)
+    }
+}
+
 trait ProcessOption {
     /// if a configured-off value causes this value to be `None` instead of propagating the configuring-off
     const REMOVE_VALUE: bool;
 }
 
-impl ProcessOption for Token![<] {
-    const REMOVE_VALUE: bool = false;
-}
-
-impl ProcessOption for Token![>] {
-    const REMOVE_VALUE: bool = false;
-}
-
-impl ProcessOption for Token![=] {
-    const REMOVE_VALUE: bool = false;
-}
-
 impl ProcessOption for syn::WhereClause {
     const REMOVE_VALUE: bool = true;
 }
 
+impl ProcessOption for syn::ImplRestriction {
+    const REMOVE_VALUE: bool = false;
+}
+
 impl ProcessOption for (Token![=], syn::Expr) {
     const REMOVE_VALUE: bool = true;
 }
@@ -300,34 +333,22 @@ impl ProcessOption for (Token![as], Ident) {
     const REMOVE_VALUE: bool = true;
 }
 
-impl ProcessOption for Token![unsafe] {
-    const REMOVE_VALUE: bool = true;
-}
-
-impl ProcessOption for Token![default] {
-    const REMOVE_VALUE: bool = true;
-}
-
-impl ProcessOption for Token![const] {
-    const REMOVE_VALUE: bool = true;
-}
-
-impl ProcessOption for Token![async] {
-    const REMOVE_VALUE: bool = true;
-}
-
 impl ProcessOption for (Option<Token![!]>, syn::Path, Token![for]) {
     const REMOVE_VALUE: bool = false;
 }
 
-impl ProcessOption for syn::Abi {
-    const REMOVE_VALUE: bool = false;
-}
-
 impl ProcessOption for syn::Variadic {
     const REMOVE_VALUE: bool = true;
 }
 
+impl ProcessOption for (Box<syn::Pat>, Token![:]) {
+    const REMOVE_VALUE: bool = false;
+}
+
+impl ProcessOption for (syn::token::Brace, Vec<syn::Item>) {
+    const REMOVE_VALUE: bool = false;
+}
+
 impl<T: Process<P> + ProcessOption, P: Phase> Process<P> for Option<T> {
     fn process(self, state: &mut State<P>) -> Option<Output<Self, P>> {
         if let Some(this) = self {
@@ -403,19 +424,8 @@ impl ProcessPunctuatedElement for syn::FnArg {
     const REMOVE_ELEMENTS: bool = true;
 }
 
-impl<P: Phase> Process<P> for Vec<syn::Stmt> {
-    fn process(self, state: &mut State<P>) -> Option<Output<Self, P>> {
-        let mut output = Output::new(Vec::new());
-        for value in self {
-            if let Some(value) = value.process(state) {
-                output = (output, value).call(|(mut output, value)| {
-                    output.push(value);
-                    output
-                });
-            }
-        }
-        Some(output)
-    }
+impl ProcessPunctuatedElement for syn::TypeParamBound {
+    const REMOVE_ELEMENTS: bool = true;
 }
 
 impl<T: Process<P>, U: Process<P>, P: Phase> Process<P> for (T, U) {
@@ -444,12 +454,17 @@ macro_rules! process_no_op {
                 Some(Output::new(self))
             }
         }
+
+        impl ProcessOption for $ty {
+            const REMOVE_VALUE: bool = false;
+        }
     };
 }
 
 process_no_op!(syn::Visibility);
 process_no_op!(syn::Lifetime);
 process_no_op!(syn::Abi);
+process_no_op!(syn::StaticMutability);
 process_no_op!(Token![as]);
 process_no_op!(Token![async]);
 process_no_op!(Token![auto]);
@@ -495,14 +510,53 @@ process_no_op!(Token![use]);
 process_no_op!(Token![where]);
 process_no_op!(Token![while]);
 process_no_op!(Token![yield]);
+process_no_op!(Token![&]);
+process_no_op!(Token![&&]);
+process_no_op!(Token![&=]);
+process_no_op!(Token![@]);
+process_no_op!(Token![^]);
+process_no_op!(Token![^=]);
 process_no_op!(Token![:]);
-process_no_op!(Token![::]);
-process_no_op!(Token![;]);
-process_no_op!(Token![=]);
-process_no_op!(Token![?]);
+process_no_op!(Token![,]);
+process_no_op!(Token![$]);
+process_no_op!(Token![.]);
 process_no_op!(Token![..]);
-process_no_op!(Token![<]);
+process_no_op!(Token![...]);
+process_no_op!(Token![..=]);
+process_no_op!(Token![=]);
+process_no_op!(Token![==]);
+process_no_op!(Token![=>]);
+process_no_op!(Token![>=]);
 process_no_op!(Token![>]);
+process_no_op!(Token![<-]);
+process_no_op!(Token![<=]);
+process_no_op!(Token![<]);
+process_no_op!(Token![-]);
+process_no_op!(Token![-=]);
+process_no_op!(Token![!=]);
+process_no_op!(Token![!]);
+process_no_op!(Token![|]);
+process_no_op!(Token![|=]);
+process_no_op!(Token![||]);
+process_no_op!(Token![::]);
+process_no_op!(Token![%]);
+process_no_op!(Token![%=]);
+process_no_op!(Token![+]);
+process_no_op!(Token![+=]);
+process_no_op!(Token![#]);
+process_no_op!(Token![?]);
+process_no_op!(Token![->]);
+process_no_op!(Token![;]);
+process_no_op!(Token![<<]);
+process_no_op!(Token![<<=]);
+process_no_op!(Token![>>]);
+process_no_op!(Token![>>=]);
+process_no_op!(Token![/]);
+process_no_op!(Token![/=]);
+process_no_op!(Token![*]);
+process_no_op!(Token![*=]);
+process_no_op!(Token![~]);
+process_no_op!(Token![_]);
 process_no_op!(syn::token::Brace);
 process_no_op!(syn::token::Bracket);
 process_no_op!(syn::token::Paren);
@@ -1489,6 +1543,71 @@ process_enum! {
     }
 }
 
+process_enum! {
+    syn::Pat {
+        Const,
+        Ident,
+        Lit,
+        Macro,
+        Or,
+        Paren,
+        Path,
+        Range,
+        Reference,
+        Rest,
+        Slice,
+        Struct,
+        Tuple,
+        TupleStruct,
+        Type,
+        Wild,
+        #[no_op]
+        _,
+    }
+}
+
+process_enum! {
+    syn::ForeignItem {
+        Fn,
+        Static,
+        Type,
+        Macro,
+        #[no_op]
+        _,
+    }
+}
+
+process_enum! {
+    syn::ImplItem {
+        Const,
+        Fn,
+        Type,
+        Macro,
+        #[no_op]
+        _,
+    }
+}
+
+process_enum! {
+    syn::TypeParamBound {
+        Trait,
+        Lifetime,
+        #[no_op]
+        _,
+    }
+}
+
+process_enum! {
+    syn::TraitItem {
+        Const,
+        Fn,
+        Type,
+        Macro,
+        #[no_op]
+        _,
+    }
+}
+
 impl<P: Phase> Process<P> for syn::ReturnType {
     fn process(self, state: &mut State<P>) -> Option<Output<Self, P>> {
         match self {
@@ -1554,6 +1673,12 @@ impl<P: Phase> Process<P> for TopItem {
     }
 }
 
+impl<P: Phase> Process<P> for syn::ImplRestriction {
+    fn process(self, _state: &mut State<P>) -> Option<Output<Self, P>> {
+        todo!("ImplRestriction is an uninhabited type as of writing, blocked on syn implementing impl restrictions")
+    }
+}
+
 pub(crate) fn process_cfgs(item: syn::Item, cfgs: Cfgs<bool>) -> syn::Result<Option<syn::Item>> {
     let mut state = State::<ProcessCfgsPhase> {
         cfgs,