Remove `NtItem` and `NtStmt`.

This involves replacing `nt_pretty_printing_compatibility_hack` with
`stream_pretty_printing_compatibility_hack`.

The handling of statements in `transcribe` is slightly different to
other nonterminal kinds, due to the lack of `from_ast` implementation
for empty statements.

Notable test changes:
- `tests/ui/proc-macro/expand-to-derive.rs`: the diff looks large but
  the only difference is the insertion of a single invisible-delimited
  group around a metavar.

1 files changed, 34 insertions, 15 deletions

diff --git a/compiler/rustc_expand/src/base.rs b/compiler/rustc_expand/src/base.rs
index 86b12f6be4e..895efe05e11 100644
--- a/compiler/rustc_expand/src/base.rs
+++ b/compiler/rustc_expand/src/base.rs
@@ -7,7 +7,7 @@ use std::sync::Arc;
 
 use rustc_ast::attr::{AttributeExt, MarkedAttrs};
 use rustc_ast::ptr::P;
-use rustc_ast::token::Nonterminal;
+use rustc_ast::token::MetaVarKind;
 use rustc_ast::tokenstream::TokenStream;
 use rustc_ast::visit::{AssocCtxt, Visitor};
 use rustc_ast::{self as ast, AttrVec, Attribute, HasAttrs, Item, NodeId, PatKind};
@@ -19,7 +19,7 @@ use rustc_feature::Features;
 use rustc_hir as hir;
 use rustc_lint_defs::{BufferedEarlyLint, RegisteredTools};
 use rustc_parse::MACRO_ARGUMENTS;
-use rustc_parse::parser::Parser;
+use rustc_parse::parser::{ForceCollect, Parser};
 use rustc_session::config::CollapseMacroDebuginfo;
 use rustc_session::parse::ParseSess;
 use rustc_session::{Limit, Session};
@@ -1405,13 +1405,13 @@ pub fn parse_macro_name_and_helper_attrs(
 /// If this item looks like a specific enums from `rental`, emit a fatal error.
 /// See #73345 and #83125 for more details.
 /// FIXME(#73933): Remove this eventually.
-fn pretty_printing_compatibility_hack(item: &Item, sess: &Session) {
+fn pretty_printing_compatibility_hack(item: &Item, psess: &ParseSess) {
     let name = item.ident.name;
     if name == sym::ProceduralMasqueradeDummyType
         && let ast::ItemKind::Enum(enum_def, _) = &item.kind
         && let [variant] = &*enum_def.variants
         && variant.ident.name == sym::Input
-        && let FileName::Real(real) = sess.source_map().span_to_filename(item.ident.span)
+        && let FileName::Real(real) = psess.source_map().span_to_filename(item.ident.span)
         && let Some(c) = real
             .local_path()
             .unwrap_or(Path::new(""))
@@ -1429,7 +1429,7 @@ fn pretty_printing_compatibility_hack(item: &Item, sess: &Session) {
         };
 
         if crate_matches {
-            sess.dcx().emit_fatal(errors::ProcMacroBackCompat {
+            psess.dcx().emit_fatal(errors::ProcMacroBackCompat {
                 crate_name: "rental".to_string(),
                 fixed_version: "0.5.6".to_string(),
             });
@@ -1437,7 +1437,7 @@ fn pretty_printing_compatibility_hack(item: &Item, sess: &Session) {
     }
 }
 
-pub(crate) fn ann_pretty_printing_compatibility_hack(ann: &Annotatable, sess: &Session) {
+pub(crate) fn ann_pretty_printing_compatibility_hack(ann: &Annotatable, psess: &ParseSess) {
     let item = match ann {
         Annotatable::Item(item) => item,
         Annotatable::Stmt(stmt) => match &stmt.kind {
@@ -1446,17 +1446,36 @@ pub(crate) fn ann_pretty_printing_compatibility_hack(ann: &Annotatable, sess: &S
         },
         _ => return,
     };
-    pretty_printing_compatibility_hack(item, sess)
+    pretty_printing_compatibility_hack(item, psess)
 }
 
-pub(crate) fn nt_pretty_printing_compatibility_hack(nt: &Nonterminal, sess: &Session) {
-    let item = match nt {
-        Nonterminal::NtItem(item) => item,
-        Nonterminal::NtStmt(stmt) => match &stmt.kind {
-            ast::StmtKind::Item(item) => item,
-            _ => return,
-        },
+pub(crate) fn stream_pretty_printing_compatibility_hack(
+    kind: MetaVarKind,
+    stream: &TokenStream,
+    psess: &ParseSess,
+) {
+    let item = match kind {
+        MetaVarKind::Item => {
+            let mut parser = Parser::new(psess, stream.clone(), None);
+            // No need to collect tokens for this simple check.
+            parser
+                .parse_item(ForceCollect::No)
+                .expect("failed to reparse item")
+                .expect("an actual item")
+        }
+        MetaVarKind::Stmt => {
+            let mut parser = Parser::new(psess, stream.clone(), None);
+            // No need to collect tokens for this simple check.
+            let stmt = parser
+                .parse_stmt(ForceCollect::No)
+                .expect("failed to reparse")
+                .expect("an actual stmt");
+            match &stmt.kind {
+                ast::StmtKind::Item(item) => item.clone(),
+                _ => return,
+            }
+        }
         _ => return,
     };
-    pretty_printing_compatibility_hack(item, sess)
+    pretty_printing_compatibility_hack(&item, psess)
 }