From 34dc8d25c1e461cc311d6d4404f74502513cd3ae Mon Sep 17 00:00:00 2001
From: Edwin Cheng <edwin0cheng@gmail.com>
Date: Wed, 18 Mar 2020 17:47:59 +0800
Subject: Add basic custom derive lowering

---
 crates/ra_hir_def/src/nameres/collector.rs | 60 ++++++++++++++++++++++++++----
 1 file changed, 53 insertions(+), 7 deletions(-)

(limited to 'crates/ra_hir_def/src/nameres')

diff --git a/crates/ra_hir_def/src/nameres/collector.rs b/crates/ra_hir_def/src/nameres/collector.rs
index 5b292c250..76be71a30 100644
--- a/crates/ra_hir_def/src/nameres/collector.rs
+++ b/crates/ra_hir_def/src/nameres/collector.rs
@@ -7,6 +7,7 @@ use hir_expand::{
     builtin_derive::find_builtin_derive,
     builtin_macro::find_builtin_macro,
     name::{name, AsName, Name},
+    proc_macro::ProcMacroExpander,
     HirFileId, MacroCallId, MacroDefId, MacroDefKind,
 };
 use ra_cfg::CfgOptions;
@@ -238,6 +239,18 @@ impl DefCollector<'_> {
         self.def_map.modules[module_id].scope.define_legacy_macro(name, mac);
     }
 
+    /// Define a proc macro
+    ///
+    /// A proc macro is similar to normal macro scope, but it would not visiable in legacy textual scoped.
+    /// And unconditionally exported.
+    fn define_proc_macro(&mut self, name: Name, macro_: MacroDefId) {
+        self.update(
+            self.def_map.root,
+            &[(name, PerNs::macros(macro_, Visibility::Public))],
+            Visibility::Public,
+        );
+    }
+
     /// Import macros from `#[macro_use] extern crate`.
     fn import_macros_from_extern_crate(
         &mut self,
@@ -537,8 +550,9 @@ impl DefCollector<'_> {
             true
         });
         attribute_macros.retain(|directive| {
-            if let Some(call_id) =
-                directive.ast_id.as_call_id(self.db, |path| self.resolve_attribute_macro(&path))
+            if let Some(call_id) = directive
+                .ast_id
+                .as_call_id(self.db, |path| self.resolve_attribute_macro(&directive, &path))
             {
                 resolved.push((directive.module_id, call_id, 0));
                 res = ReachedFixedPoint::No;
@@ -562,9 +576,11 @@ impl DefCollector<'_> {
         res
     }
 
-    fn resolve_attribute_macro(&self, path: &ModPath) -> Option<MacroDefId> {
-        // FIXME this is currently super hacky, just enough to support the
-        // built-in derives
+    fn resolve_attribute_macro(
+        &self,
+        directive: &DeriveDirective,
+        path: &ModPath,
+    ) -> Option<MacroDefId> {
         if let Some(name) = path.as_ident() {
             // FIXME this should actually be handled with the normal name
             // resolution; the std lib defines built-in stubs for the derives,
@@ -573,7 +589,15 @@ impl DefCollector<'_> {
                 return Some(def_id);
             }
         }
-        None
+        let resolved_res = self.def_map.resolve_path_fp_with_macro(
+            self.db,
+            ResolveMode::Other,
+            directive.module_id,
+            &path,
+            BuiltinShadowMode::Module,
+        );
+
+        resolved_res.resolved_def.take_macros()
     }
 
     fn collect_macro_expansion(
@@ -776,8 +800,8 @@ impl ModCollector<'_, '_> {
         // FIXME: check attrs to see if this is an attribute macro invocation;
         // in which case we don't add the invocation, just a single attribute
         // macro invocation
-
         self.collect_derives(attrs, def);
+        self.collect_proc_macro(attrs);
 
         let name = def.name.clone();
         let container = ContainerId::ModuleId(module);
@@ -854,6 +878,28 @@ impl ModCollector<'_, '_> {
         }
     }
 
+    fn collect_proc_macro(&mut self, attrs: &Attrs) {
+        if let Some(derive_subtree) = attrs.by_key("proc_macro_derive").tt_values().next() {
+            if let Some(tt) = derive_subtree.token_trees.get(0) {
+                let ident = match &tt {
+                    tt::TokenTree::Leaf(tt::Leaf::Ident(ident)) => ident,
+                    _ => return, // anything else would be an error (which we currently ignore)
+                };
+                let name = ident.as_name();
+                let krate = self.def_collector.def_map.krate;
+                let expander = ProcMacroExpander::new(krate);
+
+                let macro_id = MacroDefId {
+                    ast_id: None,
+                    krate: Some(krate),
+                    kind: MacroDefKind::ProcMacro(expander),
+                };
+
+                self.def_collector.define_proc_macro(name.clone(), macro_id);
+            }
+        }
+    }
+
     fn collect_macro(&mut self, mac: &raw::MacroData) {
         let mut ast_id = AstIdWithPath::new(self.file_id, mac.ast_id, mac.path.clone());
 
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