resolve: Block expansion of a derive container until all its derives are resolved

Also mark derive helpers as known as a part of the derive container's expansion instead of expansion of the derives themselves which may happen too late.

1 files changed, 19 insertions, 1 deletions

diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index a63c4181d5e..f0397558a1d 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -11,6 +11,7 @@ use crate::ptr::P;
 use crate::symbol::{kw, sym, Ident, Symbol};
 use crate::{ThinVec, MACRO_ARGUMENTS};
 use crate::tokenstream::{self, TokenStream, TokenTree};
+use crate::visit::Visitor;
 
 use errors::{DiagnosticBuilder, DiagnosticId};
 use smallvec::{smallvec, SmallVec};
@@ -72,6 +73,17 @@ impl Annotatable {
         }
     }
 
+    pub fn visit_with<'a, V: Visitor<'a>>(&'a self, visitor: &mut V) {
+        match self {
+            Annotatable::Item(item) => visitor.visit_item(item),
+            Annotatable::TraitItem(trait_item) => visitor.visit_trait_item(trait_item),
+            Annotatable::ImplItem(impl_item) => visitor.visit_impl_item(impl_item),
+            Annotatable::ForeignItem(foreign_item) => visitor.visit_foreign_item(foreign_item),
+            Annotatable::Stmt(stmt) => visitor.visit_stmt(stmt),
+            Annotatable::Expr(expr) => visitor.visit_expr(expr),
+        }
+    }
+
     pub fn expect_item(self) -> P<ast::Item> {
         match self {
             Annotatable::Item(i) => i,
@@ -637,6 +649,12 @@ impl SyntaxExtension {
 
 pub type NamedSyntaxExtension = (Name, SyntaxExtension);
 
+/// Result of resolving a macro invocation.
+pub enum InvocationRes {
+    Single(Lrc<SyntaxExtension>),
+    DeriveContainer(Vec<Lrc<SyntaxExtension>>),
+}
+
 /// Error type that denotes indeterminacy.
 pub struct Indeterminate;
 
@@ -664,7 +682,7 @@ pub trait Resolver {
 
     fn resolve_macro_invocation(
         &mut self, invoc: &Invocation, eager_expansion_root: ExpnId, force: bool
-    ) -> Result<Option<Lrc<SyntaxExtension>>, Indeterminate>;
+    ) -> Result<InvocationRes, Indeterminate>;
 
     fn check_unused_macros(&self);