6 files changed, 35 insertions, 24 deletions

diff --git a/crates/hir_expand/src/db.rs b/crates/hir_expand/src/db.rs
index 710694a34..b591130ca 100644
--- a/crates/hir_expand/src/db.rs
+++ b/crates/hir_expand/src/db.rs
@@ -143,7 +143,7 @@ pub(crate) fn macro_def(
             Some(Arc::new((TokenExpander::BuiltinDerive(expander), mbe::TokenMap::default())))
         }
         MacroDefKind::BuiltInEager(_) => None,
-        MacroDefKind::CustomDerive(expander) => {
+        MacroDefKind::ProcMacro(expander) => {
             Some(Arc::new((TokenExpander::ProcMacro(expander), mbe::TokenMap::default())))
         }
     }
@@ -249,7 +249,7 @@ pub(crate) fn expand_proc_macro(
     };
 
     let expander = match loc.def.kind {
-        MacroDefKind::CustomDerive(expander) => expander,
+        MacroDefKind::ProcMacro(expander) => expander,
         _ => unreachable!(),
     };
 
diff --git a/crates/hir_expand/src/eager.rs b/crates/hir_expand/src/eager.rs
index 10c45646f..2f37d7189 100644
--- a/crates/hir_expand/src/eager.rs
+++ b/crates/hir_expand/src/eager.rs
@@ -129,7 +129,7 @@ fn eager_macro_recur(
             MacroDefKind::Declarative
             | MacroDefKind::BuiltIn(_)
             | MacroDefKind::BuiltInDerive(_)
-            | MacroDefKind::CustomDerive(_) => {
+            | MacroDefKind::ProcMacro(_) => {
                 let expanded = lazy_expand(db, &def, curr.with_value(child.clone()), krate)?;
                 // replace macro inside
                 eager_macro_recur(db, expanded, krate, macro_resolver)?
diff --git a/crates/hir_expand/src/hygiene.rs b/crates/hir_expand/src/hygiene.rs
index 845e9cbc1..d383b968d 100644
--- a/crates/hir_expand/src/hygiene.rs
+++ b/crates/hir_expand/src/hygiene.rs
@@ -33,7 +33,7 @@ impl Hygiene {
                         MacroDefKind::BuiltIn(_) => (None, false),
                         MacroDefKind::BuiltInDerive(_) => (None, false),
                         MacroDefKind::BuiltInEager(_) => (None, false),
-                        MacroDefKind::CustomDerive(_) => (None, false),
+                        MacroDefKind::ProcMacro(_) => (None, false),
                     }
                 }
                 MacroCallId::EagerMacro(_id) => (None, false),
diff --git a/crates/hir_expand/src/lib.rs b/crates/hir_expand/src/lib.rs
index 2be15e841..17f1178ed 100644
--- a/crates/hir_expand/src/lib.rs
+++ b/crates/hir_expand/src/lib.rs
@@ -246,7 +246,7 @@ pub enum MacroDefKind {
     // FIXME: maybe just Builtin and rename BuiltinFnLikeExpander to BuiltinExpander
     BuiltInDerive(BuiltinDeriveExpander),
     BuiltInEager(EagerExpander),
-    CustomDerive(ProcMacroExpander),
+    ProcMacro(ProcMacroExpander),
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
diff --git a/crates/hir_expand/src/name.rs b/crates/hir_expand/src/name.rs
index 49841c7a1..a5750d829 100644
--- a/crates/hir_expand/src/name.rs
+++ b/crates/hir_expand/src/name.rs
@@ -43,8 +43,8 @@ impl Name {
     }
 
     /// Shortcut to create inline plain text name
-    const fn new_inline_ascii(text: &[u8]) -> Name {
-        Name::new_text(SmolStr::new_inline_from_ascii(text.len(), text))
+    const fn new_inline(text: &str) -> Name {
+        Name::new_text(SmolStr::new_inline(text))
     }
 
     /// Resolve a name from the text of token.
@@ -127,7 +127,7 @@ pub mod known {
             $(
                 #[allow(bad_style)]
                 pub const $ident: super::Name =
-                    super::Name::new_inline_ascii(stringify!($ident).as_bytes());
+                    super::Name::new_inline(stringify!($ident));
             )*
         };
     }
@@ -210,8 +210,8 @@ pub mod known {
     );
 
     // self/Self cannot be used as an identifier
-    pub const SELF_PARAM: super::Name = super::Name::new_inline_ascii(b"self");
-    pub const SELF_TYPE: super::Name = super::Name::new_inline_ascii(b"Self");
+    pub const SELF_PARAM: super::Name = super::Name::new_inline("self");
+    pub const SELF_TYPE: super::Name = super::Name::new_inline("Self");
 
     #[macro_export]
     macro_rules! name {
diff --git a/crates/hir_expand/src/proc_macro.rs b/crates/hir_expand/src/proc_macro.rs
index 80255ea32..7505cb061 100644
--- a/crates/hir_expand/src/proc_macro.rs
+++ b/crates/hir_expand/src/proc_macro.rs
@@ -7,7 +7,7 @@ use tt::buffer::{Cursor, TokenBuffer};
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
 pub struct ProcMacroExpander {
     krate: CrateId,
-    proc_macro_id: ProcMacroId,
+    proc_macro_id: Option<ProcMacroId>,
 }
 
 macro_rules! err {
@@ -20,8 +20,14 @@ macro_rules! err {
 }
 
 impl ProcMacroExpander {
-    pub fn new(krate: CrateId, proc_macro_id: ProcMacroId) -> ProcMacroExpander {
-        ProcMacroExpander { krate, proc_macro_id }
+    pub fn new(krate: CrateId, proc_macro_id: ProcMacroId) -> Self {
+        Self { krate, proc_macro_id: Some(proc_macro_id) }
+    }
+
+    pub fn dummy(krate: CrateId) -> Self {
+        // FIXME: Should store the name for better errors
+        // FIXME: I think this is the second layer of "dummy" expansion, we should reduce that
+        Self { krate, proc_macro_id: None }
     }
 
     pub fn expand(
@@ -30,17 +36,22 @@ impl ProcMacroExpander {
         _id: LazyMacroId,
         tt: &tt::Subtree,
     ) -> Result<tt::Subtree, mbe::ExpandError> {
-        let krate_graph = db.crate_graph();
-        let proc_macro = krate_graph[self.krate]
-            .proc_macro
-            .get(self.proc_macro_id.0 as usize)
-            .clone()
-            .ok_or_else(|| err!("No derive macro found."))?;
-
-        let tt = remove_derive_attrs(tt)
-            .ok_or_else(|| err!("Fail to remove derive for custom derive"))?;
-
-        proc_macro.expander.expand(&tt, None).map_err(mbe::ExpandError::from)
+        match self.proc_macro_id {
+            Some(id) => {
+                let krate_graph = db.crate_graph();
+                let proc_macro = krate_graph[self.krate]
+                    .proc_macro
+                    .get(id.0 as usize)
+                    .clone()
+                    .ok_or_else(|| err!("No derive macro found."))?;
+
+                let tt = remove_derive_attrs(tt)
+                    .ok_or_else(|| err!("Fail to remove derive for custom derive"))?;
+
+                proc_macro.expander.expand(&tt, None).map_err(mbe::ExpandError::from)
+            }
+            None => Err(err!("Unresolved proc macro")),
+        }
     }
 }