Rollup merge of rust-lang#87779 - Aaron1011:stmt-ast-id, r=petrochenkov

Remove special case for statement `NodeId` assignment

We now let `noop_flat_map_stmt` assign `NodeId`s (via `visit_id`),
just as we do for other AST nodes.

compiler/rustc_expand/src/expand.rs

@@ -559,7 +559,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         self.cx.force_mode = orig_force_mode;
 
         // Finally incorporate all the expanded macros into the input AST fragment.
-        let mut placeholder_expander = PlaceholderExpander::new(self.cx, self.monotonic);
+        let mut placeholder_expander = PlaceholderExpander::default();
         while let Some(expanded_fragments) = expanded_fragments.pop() {
             for (expn_id, expanded_fragment) in expanded_fragments.into_iter().rev() {
                 placeholder_expander
@@ -1341,14 +1341,9 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
             }
         }
 
-        // The placeholder expander gives ids to statements, so we avoid folding the id here.
         // We don't use `assign_id!` - it will be called when we visit statement's contents
         // (e.g. an expression, item, or local)
-        let ast::Stmt { id, kind, span } = stmt;
-        let res = noop_flat_map_stmt_kind(kind, self)
-            .into_iter()
-            .map(|kind| ast::Stmt { id, kind, span })
-            .collect();
+        let res = noop_flat_map_stmt(stmt, self);
 
         self.cx.current_expansion.is_trailing_mac = false;
         res

compiler/rustc_expand/src/placeholders.rs

@@ -1,4 +1,3 @@
-use crate::base::ExtCtxt;
 use crate::expand::{AstFragment, AstFragmentKind};
 
 use rustc_ast as ast;
@@ -175,17 +174,12 @@ pub fn placeholder(
     }
 }
 
-pub struct PlaceholderExpander<'a, 'b> {
+#[derive(Default)]
+pub struct PlaceholderExpander {
     expanded_fragments: FxHashMap<ast::NodeId, AstFragment>,
-    cx: &'a mut ExtCtxt<'b>,
-    monotonic: bool,
 }
 
-impl<'a, 'b> PlaceholderExpander<'a, 'b> {
-    pub fn new(cx: &'a mut ExtCtxt<'b>, monotonic: bool) -> Self {
-        PlaceholderExpander { cx, expanded_fragments: FxHashMap::default(), monotonic }
-    }
-
+impl PlaceholderExpander {
     pub fn add(&mut self, id: ast::NodeId, mut fragment: AstFragment) {
         fragment.mut_visit_with(self);
         self.expanded_fragments.insert(id, fragment);
@@ -196,7 +190,7 @@ impl<'a, 'b> PlaceholderExpander<'a, 'b> {
     }
 }
 
-impl<'a, 'b> MutVisitor for PlaceholderExpander<'a, 'b> {
+impl MutVisitor for PlaceholderExpander {
     fn flat_map_arm(&mut self, arm: ast::Arm) -> SmallVec<[ast::Arm; 1]> {
         if arm.is_placeholder {
             self.remove(arm.id).make_arms()
@@ -360,15 +354,4 @@ impl<'a, 'b> MutVisitor for PlaceholderExpander<'a, 'b> {
             _ => noop_visit_ty(ty, self),
         }
     }
-
-    fn visit_block(&mut self, block: &mut P<ast::Block>) {
-        noop_visit_block(block, self);
-
-        for stmt in block.stmts.iter_mut() {
-            if self.monotonic {
-                assert_eq!(stmt.id, ast::DUMMY_NODE_ID);
-                stmt.id = self.cx.resolver.next_node_id();
-            }
-        }
-    }
 }