Merge #3692

3692: Introduce `MacroDefKind::CustomDerive` r=matklad a=edwin0cheng

This PR introduce a new `MacroDefKind` `CustomDerive`. And use a new `ProcMacroExpander` for its expanding. And the expander is a dummy for now. 

Related: #3654 

Co-authored-by: Edwin Cheng <[email protected]>

6 files changed, 64 insertions, 19 deletions

diff --git a/crates/ra_hir_expand/src/builtin_derive.rs b/crates/ra_hir_expand/src/builtin_derive.rs
index a5b50a832..79aea5806 100644
--- a/crates/ra_hir_expand/src/builtin_derive.rs
+++ b/crates/ra_hir_expand/src/builtin_derive.rs
@@ -229,9 +229,12 @@ fn partial_ord_expand(
 mod tests {
     use super::*;
     use crate::{test_db::TestDB, AstId, MacroCallId, MacroCallKind, MacroCallLoc};
+    use name::{known, Name};
     use ra_db::{fixture::WithFixture, SourceDatabase};
 
-    fn expand_builtin_derive(s: &str, expander: BuiltinDeriveExpander) -> String {
+    fn expand_builtin_derive(s: &str, name: Name) -> String {
+        let def = find_builtin_derive(&name).unwrap();
+
         let (db, file_id) = TestDB::with_single_file(&s);
         let parsed = db.parse(file_id);
         let items: Vec<_> =
@@ -239,14 +242,9 @@ mod tests {
 
         let ast_id_map = db.ast_id_map(file_id.into());
 
-        // the first one should be a macro_rules
-        let def =
-            MacroDefId { krate: None, ast_id: None, kind: MacroDefKind::BuiltInDerive(expander) };
+        let attr_id = AstId::new(file_id.into(), ast_id_map.ast_id(&items[0]));
 
-        let loc = MacroCallLoc {
-            def,
-            kind: MacroCallKind::Attr(AstId::new(file_id.into(), ast_id_map.ast_id(&items[0]))),
-        };
+        let loc = MacroCallLoc { def, kind: MacroCallKind::Attr(attr_id, name.to_string()) };
 
         let id: MacroCallId = db.intern_macro(loc).into();
         let parsed = db.parse_or_expand(id.as_file()).unwrap();
@@ -263,7 +261,7 @@ mod tests {
         #[derive(Copy)]
         struct Foo;
 "#,
-            BuiltinDeriveExpander::Copy,
+            known::Copy,
         );
 
         assert_eq!(expanded, "impl< >std::marker::CopyforFoo< >{}");
@@ -276,7 +274,7 @@ mod tests {
         #[derive(Copy)]
         struct Foo<A, B>;
 "#,
-            BuiltinDeriveExpander::Copy,
+            known::Copy,
         );
 
         assert_eq!(
@@ -292,7 +290,7 @@ mod tests {
         #[derive(Copy)]
         struct Foo<A, B, 'a, 'b>;
 "#,
-            BuiltinDeriveExpander::Copy,
+            known::Copy,
         );
 
         // We currently just ignore lifetimes
@@ -310,7 +308,7 @@ mod tests {
         #[derive(Clone)]
         struct Foo<A, B>;
 "#,
-            BuiltinDeriveExpander::Clone,
+            known::Clone,
         );
 
         assert_eq!(
diff --git a/crates/ra_hir_expand/src/db.rs b/crates/ra_hir_expand/src/db.rs
index 5a696542f..047452306 100644
--- a/crates/ra_hir_expand/src/db.rs
+++ b/crates/ra_hir_expand/src/db.rs
@@ -11,7 +11,7 @@ use ra_syntax::{algo::diff, AstNode, Parse, SyntaxKind::*, SyntaxNode};
 use crate::{
     ast_id_map::AstIdMap, BuiltinDeriveExpander, BuiltinFnLikeExpander, EagerCallLoc, EagerMacroId,
     HirFileId, HirFileIdRepr, LazyMacroId, MacroCallId, MacroCallLoc, MacroDefId, MacroDefKind,
-    MacroFile,
+    MacroFile, ProcMacroExpander,
 };
 
 #[derive(Debug, Clone, Eq, PartialEq)]
@@ -19,6 +19,7 @@ pub enum TokenExpander {
     MacroRules(mbe::MacroRules),
     Builtin(BuiltinFnLikeExpander),
     BuiltinDerive(BuiltinDeriveExpander),
+    ProcMacro(ProcMacroExpander),
 }
 
 impl TokenExpander {
@@ -33,6 +34,7 @@ impl TokenExpander {
             // FIXME switch these to ExpandResult as well
             TokenExpander::Builtin(it) => it.expand(db, id, tt).into(),
             TokenExpander::BuiltinDerive(it) => it.expand(db, id, tt).into(),
+            TokenExpander::ProcMacro(it) => it.expand(db, id, tt).into(),
         }
     }
 
@@ -41,6 +43,7 @@ impl TokenExpander {
             TokenExpander::MacroRules(it) => it.map_id_down(id),
             TokenExpander::Builtin(..) => id,
             TokenExpander::BuiltinDerive(..) => id,
+            TokenExpander::ProcMacro(..) => id,
         }
     }
 
@@ -49,6 +52,7 @@ impl TokenExpander {
             TokenExpander::MacroRules(it) => it.map_id_up(id),
             TokenExpander::Builtin(..) => (id, mbe::Origin::Call),
             TokenExpander::BuiltinDerive(..) => (id, mbe::Origin::Call),
+            TokenExpander::ProcMacro(..) => (id, mbe::Origin::Call),
         }
     }
 }
@@ -130,7 +134,10 @@ pub(crate) fn macro_def(
         MacroDefKind::BuiltInDerive(expander) => {
             Some(Arc::new((TokenExpander::BuiltinDerive(expander), mbe::TokenMap::default())))
         }
-        MacroDefKind::BuiltInEager(_expander) => None,
+        MacroDefKind::BuiltInEager(_) => None,
+        MacroDefKind::CustomDerive(expander) => {
+            Some(Arc::new((TokenExpander::ProcMacro(expander), mbe::TokenMap::default())))
+        }
     }
 }
 
diff --git a/crates/ra_hir_expand/src/eager.rs b/crates/ra_hir_expand/src/eager.rs
index 687d40294..932f47c30 100644
--- a/crates/ra_hir_expand/src/eager.rs
+++ b/crates/ra_hir_expand/src/eager.rs
@@ -112,7 +112,8 @@ fn eager_macro_recur(
             }
             MacroDefKind::Declarative
             | MacroDefKind::BuiltIn(_)
-            | MacroDefKind::BuiltInDerive(_) => {
+            | MacroDefKind::BuiltInDerive(_)
+            | MacroDefKind::CustomDerive(_) => {
                 let expanded = lazy_expand(db, &def, curr.with_value(child.clone()))?;
                 // replace macro inside
                 eager_macro_recur(db, expanded, macro_resolver)?
diff --git a/crates/ra_hir_expand/src/hygiene.rs b/crates/ra_hir_expand/src/hygiene.rs
index dfbac494f..0b41d0e95 100644
--- a/crates/ra_hir_expand/src/hygiene.rs
+++ b/crates/ra_hir_expand/src/hygiene.rs
@@ -30,6 +30,7 @@ impl Hygiene {
                         MacroDefKind::BuiltIn(_) => None,
                         MacroDefKind::BuiltInDerive(_) => None,
                         MacroDefKind::BuiltInEager(_) => None,
+                        MacroDefKind::CustomDerive(_) => None,
                     }
                 }
                 MacroCallId::EagerMacro(_id) => None,
diff --git a/crates/ra_hir_expand/src/lib.rs b/crates/ra_hir_expand/src/lib.rs
index 6b59ea4c9..86299459f 100644
--- a/crates/ra_hir_expand/src/lib.rs
+++ b/crates/ra_hir_expand/src/lib.rs
@@ -11,6 +11,7 @@ pub mod hygiene;
 pub mod diagnostics;
 pub mod builtin_derive;
 pub mod builtin_macro;
+pub mod proc_macro;
 pub mod quote;
 pub mod eager;
 
@@ -27,6 +28,7 @@ use ra_syntax::{
 use crate::ast_id_map::FileAstId;
 use crate::builtin_derive::BuiltinDeriveExpander;
 use crate::builtin_macro::{BuiltinFnLikeExpander, EagerExpander};
+use crate::proc_macro::ProcMacroExpander;
 
 #[cfg(test)]
 mod test_db;
@@ -217,6 +219,7 @@ pub enum MacroDefKind {
     // FIXME: maybe just Builtin and rename BuiltinFnLikeExpander to BuiltinExpander
     BuiltInDerive(BuiltinDeriveExpander),
     BuiltInEager(EagerExpander),
+    CustomDerive(ProcMacroExpander),
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -228,21 +231,23 @@ pub struct MacroCallLoc {
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum MacroCallKind {
     FnLike(AstId<ast::MacroCall>),
-    Attr(AstId<ast::ModuleItem>),
+    Attr(AstId<ast::ModuleItem>, String),
 }
 
 impl MacroCallKind {
     pub fn file_id(&self) -> HirFileId {
         match self {
             MacroCallKind::FnLike(ast_id) => ast_id.file_id,
-            MacroCallKind::Attr(ast_id) => ast_id.file_id,
+            MacroCallKind::Attr(ast_id, _) => ast_id.file_id,
         }
     }
 
     pub fn node(&self, db: &dyn db::AstDatabase) -> InFile<SyntaxNode> {
         match self {
             MacroCallKind::FnLike(ast_id) => ast_id.with_value(ast_id.to_node(db).syntax().clone()),
-            MacroCallKind::Attr(ast_id) => ast_id.with_value(ast_id.to_node(db).syntax().clone()),
+            MacroCallKind::Attr(ast_id, _) => {
+                ast_id.with_value(ast_id.to_node(db).syntax().clone())
+            }
         }
     }
 
@@ -251,7 +256,7 @@ impl MacroCallKind {
             MacroCallKind::FnLike(ast_id) => {
                 Some(ast_id.to_node(db).token_tree()?.syntax().clone())
             }
-            MacroCallKind::Attr(ast_id) => Some(ast_id.to_node(db).syntax().clone()),
+            MacroCallKind::Attr(ast_id, _) => Some(ast_id.to_node(db).syntax().clone()),
         }
     }
 }
diff --git a/crates/ra_hir_expand/src/proc_macro.rs b/crates/ra_hir_expand/src/proc_macro.rs
new file mode 100644
index 000000000..a8dee2052
--- /dev/null
+++ b/crates/ra_hir_expand/src/proc_macro.rs
@@ -0,0 +1,33 @@
+//! Proc Macro Expander stub
+
+use crate::{db::AstDatabase, LazyMacroId, MacroCallKind, MacroCallLoc};
+use ra_db::CrateId;
+
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
+pub struct ProcMacroExpander {
+    krate: CrateId,
+}
+
+impl ProcMacroExpander {
+    pub fn new(krate: CrateId) -> ProcMacroExpander {
+        ProcMacroExpander { krate }
+    }
+
+    pub fn expand(
+        &self,
+        db: &dyn AstDatabase,
+        id: LazyMacroId,
+        _tt: &tt::Subtree,
+    ) -> Result<tt::Subtree, mbe::ExpandError> {
+        let loc: MacroCallLoc = db.lookup_intern_macro(id);
+        let name = match loc.kind {
+            MacroCallKind::FnLike(_) => return Err(mbe::ExpandError::ConversionError),
+            MacroCallKind::Attr(_, name) => name,
+        };
+
+        log::debug!("Proc-macro-expanding name = {}", name);
+
+        // Return nothing for now
+        return Ok(tt::Subtree::default());
+    }
+}