Pass the correct per-token (not global) edition when expanding macro_rules

This was hard to do because of the separation between `mbe` and `hir-expand`, but became possible by the Salsa migration, as now `SyntaxContext` doesn't require `ExpandDatabase`, `salsa::Database` is enough.

Author: ChayimFriedman2

src/tools/rust-analyzer/Cargo.lock

@@ -1475,6 +1475,7 @@ dependencies = [
  "parser",
  "ra-ap-rustc_lexer",
  "rustc-hash 2.1.1",
+ "salsa",
  "smallvec",
  "span",
  "stdx",

src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe.rs

@@ -2051,3 +2051,33 @@ fn f() {
     "#]],
     );
 }
+
+#[test]
+fn per_token_edition() {
+    check(
+        r#"
+//- /foo.rs crate:foo edition:2024
+#[macro_export]
+macro_rules! m {
+    ($e:expr) => {};
+}
+//- /bar.rs crate:bar deps:foo edition:2021
+fn gen() -> usize {
+    0
+}
+
+fn foo() {
+    foo::m!(gen());
+}
+    "#,
+        expect![[r#"
+fn gen() -> usize {
+    0
+}
+
+fn foo() {
+    ;
+}
+    "#]],
+    );
+}

src/tools/rust-analyzer/crates/hir-expand/src/builtin/fn_macro.rs

@@ -18,7 +18,7 @@ use syntax::{
 use syntax_bridge::syntax_node_to_token_tree;
 
 use crate::{
-    EditionedFileId, ExpandError, ExpandResult, Lookup as _, MacroCallId,
+    EditionedFileId, ExpandError, ExpandResult, MacroCallId,
     builtin::quote::{WithDelimiter, dollar_crate},
     db::ExpandDatabase,
     hygiene::{span_with_call_site_ctxt, span_with_def_site_ctxt},
@@ -230,9 +230,9 @@ fn assert_expand(
     let mut iter = tt.iter();
 
     let cond = expect_fragment(
+        db,
         &mut iter,
         parser::PrefixEntryPoint::Expr,
-        id.lookup(db).krate.data(db).edition,
         tt.top_subtree().delimiter.delim_span(),
     );
     _ = iter.expect_char(',');

src/tools/rust-analyzer/crates/hir-expand/src/db.rs

@@ -299,7 +299,7 @@ pub fn expand_speculative(
         }
         MacroDefKind::Declarative(it, _) => db
             .decl_macro_expander(loc.krate, it)
-            .expand_unhygienic(tt, loc.kind.call_style(), span, loc.def.edition),
+            .expand_unhygienic(db, tt, loc.kind.call_style(), span),
         MacroDefKind::BuiltIn(_, it) => {
             it.expand(db, actual_macro_call, &tt, span).map_err(Into::into)
         }

src/tools/rust-analyzer/crates/hir-expand/src/declarative.rs

@@ -42,25 +42,25 @@ impl DeclarativeMacroExpander {
             None => self
                 .mac
                 .expand(
+                    db,
                     &tt,
                     |s| {
                         s.ctx =
                             apply_mark(db, s.ctx, call_id.into(), self.transparency, self.edition)
                     },
                     loc.kind.call_style(),
                     span,
-                    loc.def.edition,
                 )
                 .map_err(Into::into),
         }
     }
 
     pub fn expand_unhygienic(
         &self,
+        db: &dyn ExpandDatabase,
         tt: tt::TopSubtree,
         call_style: MacroCallStyle,
         call_site: Span,
-        def_site_edition: Edition,
     ) -> ExpandResult<tt::TopSubtree> {
         match self.mac.err() {
             Some(_) => ExpandResult::new(
@@ -69,7 +69,7 @@ impl DeclarativeMacroExpander {
             ),
             None => self
                 .mac
-                .expand(&tt, |_| (), call_style, call_site, def_site_edition)
+                .expand(db, &tt, |_| (), call_style, call_site)
                 .map(TupleExt::head)
                 .map_err(Into::into),
         }

src/tools/rust-analyzer/crates/mbe/Cargo.toml

@@ -18,6 +18,7 @@ rustc-hash.workspace = true
 smallvec.workspace = true
 arrayvec.workspace = true
 ra-ap-rustc_lexer.workspace = true
+salsa.workspace = true
 bitflags.workspace = true
 
 # local deps

src/tools/rust-analyzer/crates/mbe/src/benchmark.rs

@@ -2,7 +2,7 @@
 
 use intern::Symbol;
 use rustc_hash::FxHashMap;
-use span::{Edition, Span};
+use span::Span;
 use stdx::itertools::Itertools;
 use syntax::{
     AstNode,
@@ -44,16 +44,16 @@ fn benchmark_expand_macro_rules() {
     if skip_slow_tests() {
         return;
     }
+    let db = salsa::DatabaseImpl::default();
     let rules = macro_rules_fixtures();
-    let invocations = invocation_fixtures(&rules);
+    let invocations = invocation_fixtures(&db, &rules);
 
     let hash: usize = {
         let _pt = bench("mbe expand macro rules");
         invocations
             .into_iter()
             .map(|(id, tt)| {
-                let res =
-                    rules[&id].expand(&tt, |_| (), MacroCallStyle::FnLike, DUMMY, Edition::CURRENT);
+                let res = rules[&id].expand(&db, &tt, |_| (), MacroCallStyle::FnLike, DUMMY);
                 assert!(res.err.is_none());
                 res.value.0.0.len()
             })
@@ -93,6 +93,7 @@ fn macro_rules_fixtures_tt() -> FxHashMap<String, tt::TopSubtree<Span>> {
 
 /// Generate random invocation fixtures from rules
 fn invocation_fixtures(
+    db: &dyn salsa::Database,
     rules: &FxHashMap<String, DeclarativeMacro>,
 ) -> Vec<(String, tt::TopSubtree<Span>)> {
     let mut seed = 123456789;
@@ -124,10 +125,7 @@ fn invocation_fixtures(
                     }
                     let subtree = builder.build();
 
-                    if it
-                        .expand(&subtree, |_| (), MacroCallStyle::FnLike, DUMMY, Edition::CURRENT)
-                        .err
-                        .is_none()
+                    if it.expand(db, &subtree, |_| (), MacroCallStyle::FnLike, DUMMY).err.is_none()
                     {
                         res.push((name.clone(), subtree));
                         break;

src/tools/rust-analyzer/crates/mbe/src/expander.rs

@@ -7,20 +7,20 @@ mod transcriber;
 
 use intern::Symbol;
 use rustc_hash::FxHashMap;
-use span::{Edition, Span};
+use span::Span;
 
 use crate::{
     ExpandError, ExpandErrorKind, ExpandResult, MacroCallStyle, MatchedArmIndex,
     parser::MetaVarKind,
 };
 
 pub(crate) fn expand_rules(
+    db: &dyn salsa::Database,
     rules: &[crate::Rule],
     input: &tt::TopSubtree<Span>,
     marker: impl Fn(&mut Span) + Copy,
     call_style: MacroCallStyle,
     call_site: Span,
-    def_site_edition: Edition,
 ) -> ExpandResult<(tt::TopSubtree<Span>, MatchedArmIndex)> {
     let mut match_: Option<(matcher::Match<'_>, &crate::Rule, usize)> = None;
     for (idx, rule) in rules.iter().enumerate() {
@@ -29,7 +29,7 @@ pub(crate) fn expand_rules(
             continue;
         }
 
-        let new_match = matcher::match_(&rule.lhs, input, def_site_edition);
+        let new_match = matcher::match_(db, &rule.lhs, input);
 
         if new_match.err.is_none() {
             // If we find a rule that applies without errors, we're done.

src/tools/rust-analyzer/crates/mbe/src/expander/matcher.rs

@@ -63,7 +63,7 @@ use std::{rc::Rc, sync::Arc};
 
 use intern::{Symbol, sym};
 use smallvec::{SmallVec, smallvec};
-use span::{Edition, Span};
+use span::Span;
 use tt::{
     DelimSpan,
     iter::{TtElement, TtIter},
@@ -112,11 +112,11 @@ impl Match<'_> {
 
 /// Matching errors are added to the `Match`.
 pub(super) fn match_<'t>(
+    db: &dyn salsa::Database,
     pattern: &'t MetaTemplate,
     input: &'t tt::TopSubtree<Span>,
-    edition: Edition,
 ) -> Match<'t> {
-    let mut res = match_loop(pattern, input, edition);
+    let mut res = match_loop(db, pattern, input);
     res.bound_count = count(res.bindings.bindings());
     return res;
 
@@ -365,6 +365,7 @@ struct MatchState<'t> {
 /// - `error_items`: the set of items in errors, used for error-resilient parsing
 #[inline]
 fn match_loop_inner<'t>(
+    db: &dyn salsa::Database,
     src: TtIter<'t, Span>,
     stack: &[TtIter<'t, Span>],
     res: &mut Match<'t>,
@@ -375,7 +376,6 @@ fn match_loop_inner<'t>(
     eof_items: &mut SmallVec<[MatchState<'t>; 1]>,
     error_items: &mut SmallVec<[MatchState<'t>; 1]>,
     delim_span: tt::DelimSpan<Span>,
-    edition: Edition,
 ) {
     macro_rules! try_push {
         ($items: expr, $it:expr) => {
@@ -486,7 +486,7 @@ fn match_loop_inner<'t>(
             OpDelimited::Op(Op::Var { kind, name, .. }) => {
                 if let &Some(kind) = kind {
                     let mut fork = src.clone();
-                    let match_res = match_meta_var(kind, &mut fork, delim_span, edition);
+                    let match_res = match_meta_var(db, kind, &mut fork, delim_span);
                     match match_res.err {
                         None => {
                             // Some meta variables are optional (e.g. vis)
@@ -621,9 +621,9 @@ fn match_loop_inner<'t>(
 }
 
 fn match_loop<'t>(
+    db: &dyn salsa::Database,
     pattern: &'t MetaTemplate,
     src: &'t tt::TopSubtree<Span>,
-    edition: Edition,
 ) -> Match<'t> {
     let span = src.top_subtree().delimiter.delim_span();
     let mut src = src.iter();
@@ -655,6 +655,7 @@ fn match_loop<'t>(
         stdx::always!(next_items.is_empty());
 
         match_loop_inner(
+            db,
             src.clone(),
             &stack,
             &mut res,
@@ -665,7 +666,6 @@ fn match_loop<'t>(
             &mut eof_items,
             &mut error_items,
             span,
-            edition,
         );
         stdx::always!(cur_items.is_empty());
 
@@ -772,14 +772,14 @@ fn match_loop<'t>(
 }
 
 fn match_meta_var<'t>(
+    db: &dyn salsa::Database,
     kind: MetaVarKind,
     input: &mut TtIter<'t, Span>,
     delim_span: DelimSpan<Span>,
-    edition: Edition,
 ) -> ExpandResult<Fragment<'t>> {
     let fragment = match kind {
         MetaVarKind::Path => {
-            return expect_fragment(input, parser::PrefixEntryPoint::Path, edition, delim_span)
+            return expect_fragment(db, input, parser::PrefixEntryPoint::Path, delim_span)
                 .map(Fragment::Path);
         }
         MetaVarKind::Expr(expr) => {
@@ -807,7 +807,7 @@ fn match_meta_var<'t>(
                 }
                 _ => {}
             };
-            return expect_fragment(input, parser::PrefixEntryPoint::Expr, edition, delim_span)
+            return expect_fragment(db, input, parser::PrefixEntryPoint::Expr, delim_span)
                 .map(Fragment::Expr);
         }
         MetaVarKind::Ident | MetaVarKind::Tt | MetaVarKind::Lifetime | MetaVarKind::Literal => {
@@ -853,7 +853,7 @@ fn match_meta_var<'t>(
         MetaVarKind::Item => parser::PrefixEntryPoint::Item,
         MetaVarKind::Vis => parser::PrefixEntryPoint::Vis,
     };
-    expect_fragment(input, fragment, edition, delim_span).map(Fragment::Tokens)
+    expect_fragment(db, input, fragment, delim_span).map(Fragment::Tokens)
 }
 
 fn collect_vars(collector_fun: &mut impl FnMut(Symbol), pattern: &MetaTemplate) {

src/tools/rust-analyzer/crates/mbe/src/lib.rs

@@ -275,13 +275,13 @@ impl DeclarativeMacro {
 
     pub fn expand(
         &self,
+        db: &dyn salsa::Database,
         tt: &tt::TopSubtree<Span>,
         marker: impl Fn(&mut Span) + Copy,
         call_style: MacroCallStyle,
         call_site: Span,
-        def_site_edition: Edition,
     ) -> ExpandResult<(tt::TopSubtree<Span>, MatchedArmIndex)> {
-        expander::expand_rules(&self.rules, tt, marker, call_style, call_site, def_site_edition)
+        expander::expand_rules(db, &self.rules, tt, marker, call_style, call_site)
     }
 }
 
@@ -390,15 +390,14 @@ impl<T: Default, E> From<Result<T, E>> for ValueResult<T, E> {
 }
 
 pub fn expect_fragment<'t>(
+    db: &dyn salsa::Database,
     tt_iter: &mut TtIter<'t, Span>,
     entry_point: ::parser::PrefixEntryPoint,
-    edition: ::parser::Edition,
     delim_span: DelimSpan<Span>,
 ) -> ExpandResult<tt::TokenTreesView<'t, Span>> {
     use ::parser;
     let buffer = tt_iter.remaining();
-    // FIXME: Pass the correct edition per token. Due to the split between mbe and hir-expand it's complicated.
-    let parser_input = to_parser_input(buffer, &mut |_ctx| edition);
+    let parser_input = to_parser_input(buffer, &mut |ctx| ctx.edition(db));
     let tree_traversal = entry_point.parse(&parser_input);
     let mut cursor = buffer.cursor();
     let mut error = false;