Register macro expansion capabilities

plugins/cairo-lang-macro-attributes/src/lib.rs

@@ -12,20 +12,20 @@ use syn::{parse_macro_input, ItemFn};
 #[proc_macro_attribute]
 pub fn attribute_macro(_args: TokenStream, input: TokenStream) -> TokenStream {
     let item: ItemFn = parse_macro_input!(input as ItemFn);
+    let original_item_name = item.sig.ident.to_string();
+    let item = hide_name(item);
     let item_name = &item.sig.ident;
     let expanded = quote! {
         #item
 
-        #[no_mangle]
-        pub unsafe extern "C" fn expand(stable_token_stream: cairo_lang_macro_stable::StableTokenStream) -> cairo_lang_macro_stable::StableResultWrapper {
-            let token_stream = cairo_lang_macro::TokenStream::from_stable(&stable_token_stream);
-            let result = #item_name(token_stream);
-            let result: cairo_lang_macro_stable::StableProcMacroResult = result.into_stable();
-            cairo_lang_macro_stable::StableResultWrapper {
-                input: stable_token_stream,
-                output: result,
-            }
-        }
+        #[::cairo_lang_macro::linkme::distributed_slice(::cairo_lang_macro::MACRO_DEFINITIONS_SLICE)]
+        #[linkme(crate = ::cairo_lang_macro::linkme)]
+        static MACRO_DEFINITIONS_SLICE_DESERIALIZE: ::cairo_lang_macro::ExpansionDefinition =
+            ::cairo_lang_macro::ExpansionDefinition{
+                name: #original_item_name,
+                kind: ::cairo_lang_macro::ExpansionKind::Attr,
+                fun: #item_name,
+            };
     };
     TokenStream::from(expanded)
 }
@@ -50,12 +50,8 @@ pub fn attribute_macro(_args: TokenStream, input: TokenStream) -> TokenStream {
 /// # Safety
 #[proc_macro_attribute]
 pub fn aux_data_collection_callback(_args: TokenStream, input: TokenStream) -> TokenStream {
-    let mut item: ItemFn = parse_macro_input!(input as ItemFn);
-    // Rename item to hide it from the macro source code.
-    let id = short_hash(item.sig.ident.to_string());
-    let item_name = format!("{}_{}", item.sig.ident, id);
-    item.sig.ident = syn::Ident::new(item_name.as_str(), item.sig.ident.span());
-
+    let item: ItemFn = parse_macro_input!(input as ItemFn);
+    let item = hide_name(item);
     let item_name = &item.sig.ident;
     let expanded = quote! {
         #item
@@ -66,3 +62,11 @@ pub fn aux_data_collection_callback(_args: TokenStream, input: TokenStream) -> T
     };
     TokenStream::from(expanded)
 }
+
+/// Rename item to hide it from the macro source code.
+fn hide_name(mut item: ItemFn) -> ItemFn {
+    let id = short_hash(item.sig.ident.to_string());
+    let item_name = format!("{}_{}", item.sig.ident, id);
+    item.sig.ident = syn::Ident::new(item_name.as_str(), item.sig.ident.span());
+    item
+}

plugins/cairo-lang-macro-stable/src/lib.rs

@@ -6,6 +6,17 @@ use std::ptr::NonNull;
 
 pub mod ffi;
 
+#[repr(C)]
+#[derive(Debug)]
+pub struct StableExpansion {
+    pub name: *mut c_char,
+    pub kind: StableExpansionKind,
+}
+
+pub type StableExpansionKind = NonZeroU8;
+
+pub type StableExpansionsList = StableSlice<StableExpansion>;
+
 /// Token stream.
 ///
 /// This struct implements FFI-safe stable ABI.

plugins/cairo-lang-macro/src/lib.rs

@@ -3,13 +3,95 @@ pub use cairo_lang_macro_attributes::*;
 pub use linkme;
 
 use cairo_lang_macro_stable::ffi::StableSlice;
-use cairo_lang_macro_stable::{StableAuxData, StableProcMacroResult};
+use cairo_lang_macro_stable::{StableAuxData, StableExpansionsList, StableProcMacroResult};
+use std::ffi::{c_char, CStr};
 use std::slice;
 
 mod types;
 
 pub use types::*;
 
+#[derive(Clone)]
+pub struct ExpansionDefinition {
+    pub name: &'static str,
+    pub kind: ExpansionKind,
+    pub fun: ExpansionFunc,
+}
+
+type ExpansionFunc = fn(TokenStream) -> ProcMacroResult;
+
+/// Distributed slice for storing procedural macro code expansion capabilities.
+///
+/// Each element denotes name of the macro, and the expand function pointer.
+#[doc(hidden)]
+#[linkme::distributed_slice]
+pub static MACRO_DEFINITIONS_SLICE: [ExpansionDefinition];
+
+/// This function discovers expansion capabilities defined by the procedural macro.
+///
+/// This function needs to be accessible through the FFI interface,
+/// of the dynamic library re-exporting it.
+///
+/// # Safety
+#[no_mangle]
+#[doc(hidden)]
+pub unsafe extern "C" fn list_expansions() -> StableExpansionsList {
+    let list = MACRO_DEFINITIONS_SLICE
+        .iter()
+        .map(|m| m.clone().into_stable())
+        .collect();
+    StableSlice::new(list)
+}
+
+/// Free the memory allocated for the [`StableProcMacroResult`].
+///
+/// This function needs to be accessible through the FFI interface,
+/// of the dynamic library re-exporting it.
+///
+/// # Safety
+#[no_mangle]
+#[doc(hidden)]
+pub unsafe extern "C" fn free_expansions_list(list: StableExpansionsList) {
+    let v = list.into_owned();
+    v.into_iter().for_each(|v| {
+        ExpansionDefinition::free_owned(v);
+    });
+}
+
+/// The code expansion callback.
+///
+/// This function needs to be accessible through the FFI interface,
+/// of the dynamic library re-exporting it.
+///
+/// The function will be called for each code expansion by the procedural macro.
+///
+/// # Safety
+#[no_mangle]
+#[doc(hidden)]
+pub unsafe extern "C" fn expand(
+    item_name: *const c_char,
+    stable_token_stream: cairo_lang_macro_stable::StableTokenStream,
+) -> cairo_lang_macro_stable::StableResultWrapper {
+    let token_stream = TokenStream::from_stable(&stable_token_stream);
+    let item_name = CStr::from_ptr(item_name).to_string_lossy().to_string();
+    let fun = MACRO_DEFINITIONS_SLICE
+        .iter()
+        .find_map(|m| {
+            if m.name == item_name.as_str() {
+                Some(m.fun)
+            } else {
+                None
+            }
+        })
+        .expect("proc macro not found");
+    let result = fun(token_stream);
+    let result: StableProcMacroResult = result.into_stable();
+    cairo_lang_macro_stable::StableResultWrapper {
+        input: stable_token_stream,
+        output: result,
+    }
+}
+
 /// Free the memory allocated for the [`StableProcMacroResult`].
 ///
 /// This function needs to be accessible through the FFI interface,

plugins/cairo-lang-macro/src/types/conversion.rs

@@ -1,8 +1,11 @@
-use crate::{AuxData, Diagnostic, ProcMacroResult, Severity, TokenStream, TokenStreamMetadata};
+use crate::{
+    AuxData, Diagnostic, ExpansionDefinition, ProcMacroResult, Severity, TokenStream,
+    TokenStreamMetadata,
+};
 use cairo_lang_macro_stable::ffi::StableSlice;
 use cairo_lang_macro_stable::{
-    StableAuxData, StableDiagnostic, StableProcMacroResult, StableSeverity, StableTokenStream,
-    StableTokenStreamMetadata,
+    StableAuxData, StableDiagnostic, StableExpansion, StableProcMacroResult, StableSeverity,
+    StableTokenStream, StableTokenStreamMetadata,
 };
 use std::ffi::{c_char, CStr, CString};
 use std::num::NonZeroU8;
@@ -351,6 +354,30 @@ impl Severity {
     }
 }
 
+impl ExpansionDefinition {
+    // Convert to FFI-safe representation.
+    ///
+    /// # Safety
+    #[doc(hidden)]
+    pub fn into_stable(self) -> StableExpansion {
+        StableExpansion {
+            name: CString::new(self.name).unwrap().into_raw(),
+            kind: self.kind.into_stable(),
+        }
+    }
+
+    /// Take the ownership of the string.
+    ///
+    /// Useful when you need to free the allocated memory.
+    /// Only use on the same side of FFI-barrier, where the memory has been allocated.
+    ///
+    /// # Safety
+    #[doc(hidden)]
+    pub unsafe fn free_owned(expansion: StableExpansion) {
+        let _ = from_raw_cstring(expansion.name);
+    }
+}
+
 // Create a string from a raw pointer to a c_char.
 // Note that this will free the underlying memory.
 unsafe fn from_raw_cstring(raw: *mut c_char) -> String {

plugins/cairo-lang-macro/src/types/expansions.rs

@@ -0,0 +1,33 @@
+use cairo_lang_macro_stable::StableExpansionKind;
+use std::num::NonZeroU8;
+
+#[derive(Clone)]
+pub enum ExpansionKind {
+    Attr = 1,
+    Derive = 2,
+    Inline = 3,
+}
+
+impl ExpansionKind {
+    /// Convert to FFI-safe representation.
+    /// # Safety
+    #[doc(hidden)]
+    pub fn into_stable(self) -> StableExpansionKind {
+        NonZeroU8::try_from(self as u8).unwrap()
+    }
+
+    /// Convert to native Rust representation.
+    ///
+    /// # Safety
+    #[doc(hidden)]
+    pub unsafe fn from_stable(kind: &StableExpansionKind) -> Self {
+        if *kind == Self::Attr.into_stable() {
+            Self::Attr
+        } else if *kind == Self::Derive.into_stable() {
+            Self::Derive
+        } else {
+            // Note that it defaults to inline for unknown values.
+            Self::Inline
+        }
+    }
+}

plugins/cairo-lang-macro/src/types/mod.rs

@@ -2,6 +2,9 @@ use std::fmt::Display;
 use std::vec::IntoIter;
 
 mod conversion;
+mod expansions;
+
+pub use expansions::*;
 
 #[derive(Debug)]
 pub enum ProcMacroResult {

scarb/src/compiler/plugin/proc_macro/ffi.rs

@@ -9,6 +9,7 @@ use cairo_lang_syntax::node::db::SyntaxGroup;
 use cairo_lang_syntax::node::{ast, TypedSyntaxNode};
 use camino::Utf8PathBuf;
 use libloading::{Library, Symbol};
+use std::ffi::{c_char, CString};
 use std::fmt::Debug;
 
 use crate::compiler::plugin::proc_macro::compilation::SharedLibraryProvider;
@@ -79,9 +80,15 @@ impl ProcMacroInstance {
     pub(crate) fn generate_code(&self, token_stream: TokenStream) -> ProcMacroResult {
         // This must be manually freed with call to from_owned_stable.
         let stable_token_stream = token_stream.into_stable();
+        // Allocate proc macro name.
+        let item_name = CString::new(self.package_id.name.to_string())
+            .unwrap()
+            .into_raw();
         // Call FFI interface for code expansion.
         // Note that `stable_result` has been allocated by the dynamic library.
-        let stable_result = (self.plugin.vtable.expand)(stable_token_stream);
+        let stable_result = (self.plugin.vtable.expand)(item_name, stable_token_stream);
+        // Free proc macro name.
+        let _ = unsafe { CString::from_raw(item_name) };
         // Free the memory allocated by the `stable_token_stream`.
         // This will call `CString::from_raw` under the hood, to take ownership.
         unsafe {
@@ -113,7 +120,7 @@ impl ProcMacroInstance {
     }
 }
 
-type ExpandCode = extern "C" fn(StableTokenStream) -> StableResultWrapper;
+type ExpandCode = extern "C" fn(*const c_char, StableTokenStream) -> StableResultWrapper;
 type FreeResult = extern "C" fn(StableProcMacroResult);
 type AuxDataCallback = extern "C" fn(StableSlice<StableAuxData>) -> StableSlice<StableAuxData>;
 

scarb/tests/build_cairo_plugin.rs

@@ -96,7 +96,7 @@ fn simple_project(t: &impl PathChild) {
         use cairo_lang_macro::{ProcMacroResult, TokenStream, attribute_macro, AuxData};
 
         #[attribute_macro]
-        pub fn some_macro(token_stream: TokenStream) -> ProcMacroResult {
+        pub fn some(token_stream: TokenStream) -> ProcMacroResult {
             let _code = token_stream.to_string();
             ProcMacroResult::Leave { diagnostics: Vec::new() }
         }
@@ -271,7 +271,7 @@ fn can_emit_plugin_warning() {
         use cairo_lang_macro::{ProcMacroResult, TokenStream, attribute_macro, Diagnostic};
 
         #[attribute_macro]
-        pub fn some_macro(token_stream: TokenStream) -> ProcMacroResult {
+        pub fn some(token_stream: TokenStream) -> ProcMacroResult {
             let _code = token_stream.to_string();
             let diag = Diagnostic::warn("Some warning from macro.");
             ProcMacroResult::Leave { diagnostics: vec![diag] }
@@ -318,7 +318,7 @@ fn can_emit_plugin_error() {
         use cairo_lang_macro::{ProcMacroResult, TokenStream, attribute_macro, Diagnostic};
 
         #[attribute_macro]
-        pub fn some_macro(token_stream: TokenStream) -> ProcMacroResult {
+        pub fn some(token_stream: TokenStream) -> ProcMacroResult {
             let _code = token_stream.to_string();
             let diag = Diagnostic::error("Some error from macro.");
             ProcMacroResult::Leave { diagnostics: vec![diag] }
@@ -365,7 +365,7 @@ fn can_remove_original_node() {
         use cairo_lang_macro::{ProcMacroResult, TokenStream, attribute_macro};
 
         #[attribute_macro]
-        pub fn some_macro(_: TokenStream) -> ProcMacroResult {
+        pub fn some(_: TokenStream) -> ProcMacroResult {
             ProcMacroResult::Remove { diagnostics: Vec::new() }
         }
         "#},
@@ -412,7 +412,7 @@ fn can_replace_original_node() {
         use cairo_lang_macro::{ProcMacroResult, TokenStream, attribute_macro};
 
         #[attribute_macro]
-        pub fn some_macro(token_stream: TokenStream) -> ProcMacroResult {
+        pub fn some(token_stream: TokenStream) -> ProcMacroResult {
             let token_stream = TokenStream::new(
                 token_stream
                     .to_string()
@@ -471,7 +471,7 @@ fn can_return_aux_data_from_plugin() {
         }
 
         #[attribute_macro]
-        pub fn some_macro(token_stream: TokenStream) -> ProcMacroResult {
+        pub fn some(token_stream: TokenStream) -> ProcMacroResult {
             let token_stream = TokenStream::new(
                 token_stream
                     .to_string()
@@ -542,7 +542,7 @@ fn can_read_token_stream_metadata() {
         use cairo_lang_macro::{ProcMacroResult, TokenStream, attribute_macro};
 
         #[attribute_macro]
-        pub fn some_macro(token_stream: TokenStream) -> ProcMacroResult {
+        pub fn some(token_stream: TokenStream) -> ProcMacroResult {
             println!("{:#?}", token_stream.metadata());
             ProcMacroResult::Leave { diagnostics: Vec::new() }
         }