Rollup merge of rust-lang#92575 - petrochenkov:cratenodeid, r=Aaron1011

ast: Always keep a `NodeId` in `ast::Crate`

This makes it more uniform with other expanded nodes.
It makes generic code in rust-lang#92573 simpler in particular.

This is another follow-up to rust-lang#91313.
r? `@Aaron1011`

compiler/rustc_ast/src/ast.rs

@@ -510,8 +510,10 @@ pub struct Crate {
     pub attrs: Vec<Attribute>,
     pub items: Vec<P<Item>>,
     pub span: Span,
-    // Placeholder ID if the crate node is a macro placeholder.
-    pub is_placeholder: Option<NodeId>,
+    /// Must be equal to `CRATE_NODE_ID` after the crate root is expanded, but may hold
+    /// expansion placeholders or an unassigned value (`DUMMY_NODE_ID`) before that.
+    pub id: NodeId,
+    pub is_placeholder: bool,
 }
 
 /// Possible values inside of compile-time attribute lists.

compiler/rustc_ast/src/mut_visit.rs

@@ -1109,7 +1109,8 @@ pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
 }
 
 pub fn noop_visit_crate<T: MutVisitor>(krate: &mut Crate, vis: &mut T) {
-    let Crate { attrs, items, span, is_placeholder: _ } = krate;
+    let Crate { attrs, items, span, id, is_placeholder: _ } = krate;
+    vis.visit_id(id);
     visit_attrs(attrs, vis);
     items.flat_map_in_place(|item| vis.flat_map_item(item));
     vis.visit_span(span);
@@ -1554,6 +1555,7 @@ impl DummyAstNode for Crate {
             attrs: Default::default(),
             items: Default::default(),
             span: Default::default(),
+            id: DUMMY_NODE_ID,
             is_placeholder: Default::default(),
         }
     }

compiler/rustc_expand/src/expand.rs

@@ -377,6 +377,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             dir_path,
         });
         let krate = self.fully_expand_fragment(AstFragment::Crate(krate)).make_crate();
+        assert_eq!(krate.id, ast::CRATE_NODE_ID);
         self.cx.trace_macros_diag();
         krate
     }
@@ -1169,7 +1170,8 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
                         attrs: Vec::new(),
                         items: Vec::new(),
                         span,
-                        is_placeholder: None,
+                        id: self.cx.resolver.next_node_id(),
+                        is_placeholder: false,
                     };
                 }
             };
@@ -1180,7 +1182,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
                     .make_crate();
             }
 
-            noop_visit_crate(&mut krate, self);
+            assign_id!(self, &mut krate.id, || noop_visit_crate(&mut krate, self));
             krate
         })
     }

compiler/rustc_expand/src/placeholders.rs

@@ -50,7 +50,8 @@ pub fn placeholder(
             attrs: Default::default(),
             items: Default::default(),
             span,
-            is_placeholder: Some(id),
+            id,
+            is_placeholder: true,
         }),
         AstFragmentKind::Expr => AstFragment::Expr(expr_placeholder()),
         AstFragmentKind::OptExpr => AstFragment::OptExpr(Some(expr_placeholder())),
@@ -362,8 +363,8 @@ impl MutVisitor for PlaceholderExpander {
     }
 
     fn visit_crate(&mut self, krate: &mut ast::Crate) {
-        if let Some(id) = krate.is_placeholder {
-            *krate = self.remove(id).make_crate();
+        if krate.is_placeholder {
+            *krate = self.remove(krate.id).make_crate();
         } else {
             noop_visit_crate(krate, self)
         }

compiler/rustc_interface/src/passes.rs

@@ -3,7 +3,7 @@ use crate::proc_macro_decls;
 use crate::util;
 
 use rustc_ast::mut_visit::MutVisitor;
-use rustc_ast::{self as ast, visit};
+use rustc_ast::{self as ast, visit, DUMMY_NODE_ID};
 use rustc_borrowck as mir_borrowck;
 use rustc_codegen_ssa::back::link::emit_metadata;
 use rustc_codegen_ssa::traits::CodegenBackend;
@@ -323,7 +323,7 @@ pub fn configure_and_expand(
 
         let crate_attrs = krate.attrs.clone();
         let extern_mod_loaded = |ident: Ident, attrs, items, span| {
-            let krate = ast::Crate { attrs, items, span, is_placeholder: None };
+            let krate = ast::Crate { attrs, items, span, id: DUMMY_NODE_ID, is_placeholder: false };
             pre_expansion_lint(sess, lint_store, &krate, &crate_attrs, ident.name.as_str());
             (krate.attrs, krate.items)
         };

compiler/rustc_parse/src/parser/item.rs

@@ -27,7 +27,7 @@ impl<'a> Parser<'a> {
     /// Parses a source module as a crate. This is the main entry point for the parser.
     pub fn parse_crate_mod(&mut self) -> PResult<'a, ast::Crate> {
         let (attrs, items, span) = self.parse_mod(&token::Eof)?;
-        Ok(ast::Crate { attrs, items, span, is_placeholder: None })
+        Ok(ast::Crate { attrs, items, span, id: DUMMY_NODE_ID, is_placeholder: false })
     }
 
     /// Parses a `mod <foo> { ... }` or `mod <foo>;` item.

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -1512,8 +1512,8 @@ impl<'a, 'b> Visitor<'b> for BuildReducedGraphVisitor<'a, 'b> {
     }
 
     fn visit_crate(&mut self, krate: &'b ast::Crate) {
-        if let Some(id) = krate.is_placeholder {
-            self.visit_invoc_in_module(id);
+        if krate.is_placeholder {
+            self.visit_invoc_in_module(krate.id);
         } else {
             visit::walk_crate(self, krate);
             self.contains_macro_use(&krate.attrs);

compiler/rustc_resolve/src/def_collector.rs

@@ -344,8 +344,8 @@ impl<'a, 'b> visit::Visitor<'a> for DefCollector<'a, 'b> {
     }
 
     fn visit_crate(&mut self, krate: &'a Crate) {
-        if let Some(id) = krate.is_placeholder {
-            self.visit_macro_invoc(id)
+        if krate.is_placeholder {
+            self.visit_macro_invoc(krate.id)
         } else {
             visit::walk_crate(self, krate)
         }

compiler/rustc_resolve/src/lib.rs

@@ -68,7 +68,7 @@ use smallvec::{smallvec, SmallVec};
 use std::cell::{Cell, RefCell};
 use std::collections::{BTreeMap, BTreeSet};
 use std::ops::ControlFlow;
-use std::{cmp, fmt, iter, ptr};
+use std::{cmp, fmt, iter, mem, ptr};
 use tracing::debug;
 
 use diagnostics::{extend_span_to_previous_binding, find_span_of_binding_until_next_binding};
@@ -1394,7 +1394,7 @@ impl<'a> Resolver<'a> {
                 .chain(features.declared_lang_features.iter().map(|(feat, ..)| *feat))
                 .collect(),
             lint_buffer: LintBuffer::default(),
-            next_node_id: NodeId::from_u32(1),
+            next_node_id: CRATE_NODE_ID,
             node_id_to_def_id,
             def_id_to_node_id,
             placeholder_field_indices: Default::default(),
@@ -1430,8 +1430,7 @@ impl<'a> Resolver<'a> {
     pub fn next_node_id(&mut self) -> NodeId {
         let next =
             self.next_node_id.as_u32().checked_add(1).expect("input too large; ran out of NodeIds");
-        self.next_node_id = ast::NodeId::from_u32(next);
-        self.next_node_id
+        mem::replace(&mut self.next_node_id, ast::NodeId::from_u32(next))
     }
 
     pub fn lint_buffer(&mut self) -> &mut LintBuffer {

src/test/ui/ast-json/ast-json-noexpand-output.stdout

@@ -1 +1 @@
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+{"attrs":[{"kind":{"variant":"Normal","fields":[{"path":{"span":{"lo":0,"hi":0},"segments":[{"ident":{"name":"crate_type","span":{"lo":0,"hi":0}},"id":0,"args":null}],"tokens":null},"args":{"variant":"Eq","fields":[{"lo":0,"hi":0},{"kind":{"variant":"Interpolated","fields":[{"variant":"NtExpr","fields":[{"id":0,"kind":{"variant":"Lit","fields":[{"token":{"kind":"Str","symbol":"lib","suffix":null},"kind":{"variant":"Str","fields":["lib","Cooked"]},"span":{"lo":0,"hi":0}}]},"span":{"lo":0,"hi":0},"attrs":{"0":null},"tokens":{"0":[[{"variant":"Token","fields":[{"kind":{"variant":"Literal","fields":[{"kind":"Str","symbol":"lib","suffix":null}]},"span":{"lo":0,"hi":0}}]},"Alone"]]}}]}]},"span":{"lo":0,"hi":0}}]},"tokens":null},{"0":[[{"variant":"Token","fields":[{"kind":"Pound","span":{"lo":0,"hi":0}}]},"Joint"],[{"variant":"Token","fields":[{"kind":"Not","span":{"lo":0,"hi":0}}]},"Alone"],[{"variant":"Delimited","fields":[{"open":{"lo":0,"hi":0},"close":{"lo":0,"hi":0}},"Bracket",{"0":[[{"variant":"Token","fields":[{"kind":{"variant":"Ident","fields":["crate_type",false]},"span":{"lo":0,"hi":0}}]},"Alone"],[{"variant":"Token","fields":[{"kind":"Eq","span":{"lo":0,"hi":0}}]},"Alone"],[{"variant":"Token","fields":[{"kind":{"variant":"Literal","fields":[{"kind":"Str","symbol":"lib","suffix":null}]},"span":{"lo":0,"hi":0}}]},"Alone"]]}]},"Alone"]]}]},"id":null,"style":"Inner","span":{"lo":0,"hi":0}}],"items":[{"attrs":[],"id":0,"span":{"lo":0,"hi":0},"vis":{"kind":"Inherited","span":{"lo":0,"hi":0},"tokens":null},"ident":{"name":"core","span":{"lo":0,"hi":0}},"kind":{"variant":"ExternCrate","fields":[null]},"tokens":null}],"span":{"lo":0,"hi":0},"id":0,"is_placeholder":false}

src/test/ui/ast-json/ast-json-output.stdout

@@ -1 +1 @@
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