rework debugging to be more permanent

components/salsa-2022-macros/src/debug.rs

@@ -0,0 +1,23 @@
+use std::sync::OnceLock;
+
+use proc_macro2::TokenStream;
+
+static SALSA_DEBUG_MACRO: OnceLock<Option<String>> = OnceLock::new();
+
+pub(crate) fn debug_enabled(input_name: impl ToString) -> bool {
+    let Some(env_name) = SALSA_DEBUG_MACRO.get_or_init(|| std::env::var("SALSA_DEBUG_MACRO").ok())
+    else {
+        return false;
+    };
+
+    let input_name = input_name.to_string();
+    env_name == "*" || env_name == &input_name[..]
+}
+
+pub(crate) fn dump_tokens(input_name: impl ToString, tokens: TokenStream) -> TokenStream {
+    if debug_enabled(input_name) {
+        eprintln!("{}", tokens);
+    }
+
+    tokens
+}

components/salsa-2022-macros/src/lib.rs

@@ -39,6 +39,7 @@ pub(crate) fn literal(ident: &proc_macro2::Ident) -> proc_macro2::Literal {
 mod accumulator;
 mod configuration;
 mod db;
+mod debug;
 mod input;
 mod interned;
 mod jar;

components/salsa-2022-macros/src/tracked_fn.rs

@@ -10,6 +10,8 @@ pub(crate) fn tracked_fn(
     args: proc_macro::TokenStream,
     mut item_fn: syn::ItemFn,
 ) -> syn::Result<TokenStream> {
+    let fn_ident = item_fn.sig.ident.clone();
+
     let args: FnArgs = syn::parse(args)?;
     if item_fn.sig.inputs.is_empty() {
         return Err(syn::Error::new(
@@ -44,14 +46,17 @@ pub(crate) fn tracked_fn(
     let (config_ty, fn_struct) = fn_struct(&args, &item_fn)?;
     *item_fn.block = getter_fn(&args, &mut item_fn.sig, item_fn.block.span(), &config_ty)?;
 
-    Ok(quote! {
-        #fn_struct
+    Ok(crate::debug::dump_tokens(
+        &fn_ident,
+        quote! {
+            #fn_struct
 
-        // we generate a `'db` lifetime that clippy
-        // sometimes doesn't like
-        #[allow(clippy::needless_lifetimes)]
-        #item_fn
-    })
+            // we generate a `'db` lifetime that clippy
+            // sometimes doesn't like
+            #[allow(clippy::needless_lifetimes)]
+            #item_fn
+        },
+    ))
 }
 
 type FnArgs = Options<TrackedFn>;

components/salsa-2022-macros/src/tracked_struct.rs

@@ -16,13 +16,7 @@ pub(crate) fn tracked(
     let tokens = SalsaStruct::with_struct(args, struct_item)
         .and_then(|el| TrackedStruct(el).generate_tracked())?;
 
-    if let Ok(name) = std::env::var("NDM") {
-        if name == "*" || name == &struct_name.to_string()[..] {
-            eprintln!("{}", tokens);
-        }
-    }
-
-    Ok(tokens)
+    Ok(crate::debug::dump_tokens(&struct_name, tokens))
 }
 
 struct TrackedStruct(SalsaStruct<Self>);