Use `Resolver::visit_expansion` only with monotonic expansions.

2 files changed, 13 insertions, 10 deletions

diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 9d0d74138cd..87337c6a269 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -470,7 +470,7 @@ pub trait Resolver {
     fn add_expansions_at_stmt(&mut self, id: ast::NodeId, macros: Vec<Mark>);
 
     fn find_attr_invoc(&mut self, attrs: &mut Vec<Attribute>) -> Option<Attribute>;
-    fn resolve_invoc(&mut self, invoc: &Invocation) -> Option<Rc<SyntaxExtension>>;
+    fn resolve_invoc(&mut self, scope: Mark, invoc: &Invocation) -> Option<Rc<SyntaxExtension>>;
 }
 
 pub enum LoadedMacro {
@@ -491,7 +491,9 @@ impl Resolver for DummyResolver {
     fn add_expansions_at_stmt(&mut self, _id: ast::NodeId, _macros: Vec<Mark>) {}
 
     fn find_attr_invoc(&mut self, _attrs: &mut Vec<Attribute>) -> Option<Attribute> { None }
-    fn resolve_invoc(&mut self, _invoc: &Invocation) -> Option<Rc<SyntaxExtension>> { None }
+    fn resolve_invoc(&mut self, _scope: Mark, _invoc: &Invocation) -> Option<Rc<SyntaxExtension>> {
+        None
+    }
 }
 
 #[derive(Clone)]
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index db0183a8b3a..92c8292ae90 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -165,10 +165,6 @@ impl Invocation {
             InvocationKind::Attr { ref attr, .. } => attr.span,
         }
     }
-
-    pub fn mark(&self) -> Mark {
-        self.expansion_data.mark
-    }
 }
 
 pub struct MacroExpander<'a, 'b:'a> {
@@ -219,7 +215,9 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             let ExpansionData { depth, mark, .. } = invoc.expansion_data;
             self.cx.current_expansion = invoc.expansion_data.clone();
 
-            let expansion = match self.cx.resolver.resolve_invoc(&invoc) {
+            let scope = if self.monotonic { mark } else { orig_expansion_data.mark };
+            self.cx.current_expansion.mark = scope;
+            let expansion = match self.cx.resolver.resolve_invoc(scope, &invoc) {
                 Some(ext) => self.expand_invoc(invoc, ext),
                 None => invoc.expansion_kind.dummy(invoc.span()),
             };
@@ -267,8 +265,11 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         };
         self.cx.cfg = crate_config;
 
-        let mark = self.cx.current_expansion.mark;
-        self.cx.resolver.visit_expansion(mark, &result.0);
+        if self.monotonic {
+            let mark = self.cx.current_expansion.mark;
+            self.cx.resolver.visit_expansion(mark, &result.0);
+        }
+
         result
     }
 
@@ -314,7 +315,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
 
     /// Expand a macro invocation. Returns the result of expansion.
     fn expand_bang_invoc(&mut self, invoc: Invocation, ext: Rc<SyntaxExtension>) -> Expansion {
-        let (mark, kind) = (invoc.mark(), invoc.expansion_kind);
+        let (mark, kind) = (invoc.expansion_data.mark, invoc.expansion_kind);
         let (attrs, mac, ident, span) = match invoc.kind {
             InvocationKind::Bang { attrs, mac, ident, span } => (attrs, mac, ident, span),
             _ => unreachable!(),