Merge #7133

7133: Proper handling $crate and local_inner_macros r=jonas-schievink a=edwin0cheng

This PR introduces `HygineFrames` to store the macro definition/call site hierarchy in hyginee and when resolving `local_inner_macros` and `$crate`, we use the token to look up the corresponding frame and return the correct value.

See also: https://rustc-dev-guide.rust-lang.org/macro-expansion.html#hygiene-and-hierarchies

fixe #6890 and  #6788

r? @jonas-schievink 

Co-authored-by: Edwin Cheng <[email protected]>

7 files changed, 176 insertions, 52 deletions

diff --git a/crates/hir_def/src/path/lower.rs b/crates/hir_def/src/path/lower.rs
index 8a01e6eea..9518ac109 100644
--- a/crates/hir_def/src/path/lower.rs
+++ b/crates/hir_def/src/path/lower.rs
@@ -123,7 +123,7 @@ pub(super) fn lower_path(mut path: ast::Path, hygiene: &Hygiene) -> Option<Path>
     // We follow what it did anyway :)
     if segments.len() == 1 && kind == PathKind::Plain {
         if let Some(_macro_call) = path.syntax().parent().and_then(ast::MacroCall::cast) {
-            if let Some(crate_id) = hygiene.local_inner_macros() {
+            if let Some(crate_id) = hygiene.local_inner_macros(path) {
                 kind = PathKind::DollarCrate(crate_id);
             }
         }
diff --git a/crates/hir_expand/src/hygiene.rs b/crates/hir_expand/src/hygiene.rs
index 7ab0a5e52..6042e15b2 100644
--- a/crates/hir_expand/src/hygiene.rs
+++ b/crates/hir_expand/src/hygiene.rs
@@ -2,30 +2,94 @@
 //!
 //! Specifically, `ast` + `Hygiene` allows you to create a `Name`. Note that, at
 //! this moment, this is horribly incomplete and handles only `$crate`.
+use std::sync::Arc;
+
+use arena::{Arena, Idx};
 use base_db::CrateId;
 use either::Either;
-use syntax::ast;
+use mbe::Origin;
+use syntax::{ast, AstNode};
 
 use crate::{
     db::AstDatabase,
     name::{AsName, Name},
-    HirFileId, HirFileIdRepr, MacroCallId, MacroDefKind,
+    ExpansionInfo, HirFileId, HirFileIdRepr, MacroCallId, MacroDefKind,
 };
 
 #[derive(Clone, Debug)]
 pub struct Hygiene {
-    // This is what `$crate` expands to
-    def_crate: Option<CrateId>,
+    frames: Option<Arc<HygieneFrames>>,
+}
+
+impl Hygiene {
+    pub fn new(db: &dyn AstDatabase, file_id: HirFileId) -> Hygiene {
+        Hygiene { frames: Some(Arc::new(HygieneFrames::new(db, file_id.clone()))) }
+    }
+
+    pub fn new_unhygienic() -> Hygiene {
+        Hygiene { frames: None }
+    }
+
+    // FIXME: this should just return name
+    pub fn name_ref_to_name(&self, name_ref: ast::NameRef) -> Either<Name, CrateId> {
+        if let Some(frames) = &self.frames {
+            if name_ref.text() == "$crate" {
+                if let Some(krate) = frames.root_crate(&name_ref) {
+                    return Either::Right(krate);
+                }
+            }
+        }
+
+        Either::Left(name_ref.as_name())
+    }
+
+    pub fn local_inner_macros(&self, path: ast::Path) -> Option<CrateId> {
+        let frames = self.frames.as_ref()?;
+
+        let mut token = path.syntax().first_token()?;
+        let mut current = frames.first();
+
+        while let Some((frame, data)) =
+            current.and_then(|it| Some((it, it.expansion.as_ref()?.map_token_up(&token)?)))
+        {
+            let (mapped, origin) = data;
+            if origin == Origin::Def {
+                return if frame.local_inner { frame.krate } else { None };
+            }
+            current = Some(&frames.0[frame.call_site?]);
+            token = mapped.value;
+        }
+        None
+    }
+}
+
+#[derive(Default, Debug)]
+struct HygieneFrames(Arena<HygieneFrame>);
+
+#[derive(Clone, Debug)]
+struct HygieneFrame {
+    expansion: Option<ExpansionInfo>,
 
     // Indicate this is a local inner macro
     local_inner: bool,
+    krate: Option<CrateId>,
+
+    call_site: Option<Idx<HygieneFrame>>,
+    def_site: Option<Idx<HygieneFrame>>,
 }
 
-impl Hygiene {
-    pub fn new(db: &dyn AstDatabase, file_id: HirFileId) -> Hygiene {
-        let (def_crate, local_inner) = match file_id.0 {
+impl HygieneFrames {
+    fn new(db: &dyn AstDatabase, file_id: HirFileId) -> Self {
+        let mut frames = HygieneFrames::default();
+        frames.add(db, file_id);
+        frames
+    }
+
+    fn add(&mut self, db: &dyn AstDatabase, file_id: HirFileId) -> Option<Idx<HygieneFrame>> {
+        let (krate, local_inner) = match file_id.0 {
             HirFileIdRepr::FileId(_) => (None, false),
             HirFileIdRepr::MacroFile(macro_file) => match macro_file.macro_call_id {
+                MacroCallId::EagerMacro(_id) => (None, false),
                 MacroCallId::LazyMacro(id) => {
                     let loc = db.lookup_intern_macro(id);
                     match loc.def.kind {
@@ -36,31 +100,68 @@ impl Hygiene {
                         MacroDefKind::ProcMacro(_) => (None, false),
                     }
                 }
-                MacroCallId::EagerMacro(_id) => (None, false),
             },
         };
-        Hygiene { def_crate, local_inner }
-    }
 
-    pub fn new_unhygienic() -> Hygiene {
-        Hygiene { def_crate: None, local_inner: false }
+        let expansion = file_id.expansion_info(db);
+        let expansion = match expansion {
+            None => {
+                return Some(self.0.alloc(HygieneFrame {
+                    expansion: None,
+                    local_inner,
+                    krate,
+                    call_site: None,
+                    def_site: None,
+                }));
+            }
+            Some(it) => it,
+        };
+
+        let def_site = expansion.def.clone();
+        let call_site = expansion.arg.file_id;
+        let idx = self.0.alloc(HygieneFrame {
+            expansion: Some(expansion),
+            local_inner,
+            krate,
+            call_site: None,
+            def_site: None,
+        });
+
+        self.0[idx].call_site = self.add(db, call_site);
+        self.0[idx].def_site = def_site.and_then(|it| self.add(db, it.file_id));
+
+        Some(idx)
     }
 
-    // FIXME: this should just return name
-    pub fn name_ref_to_name(&self, name_ref: ast::NameRef) -> Either<Name, CrateId> {
-        if let Some(def_crate) = self.def_crate {
-            if name_ref.text() == "$crate" {
-                return Either::Right(def_crate);
-            }
-        }
-        Either::Left(name_ref.as_name())
+    fn first(&self) -> Option<&HygieneFrame> {
+        self.0.iter().next().map(|it| it.1)
     }
 
-    pub fn local_inner_macros(&self) -> Option<CrateId> {
-        if self.local_inner {
-            self.def_crate
-        } else {
-            None
+    fn root_crate(&self, name_ref: &ast::NameRef) -> Option<CrateId> {
+        let mut token = name_ref.syntax().first_token()?;
+        let first = self.first()?;
+        let mut result = first.krate;
+        let mut current = Some(first);
+
+        while let Some((frame, (mapped, origin))) =
+            current.and_then(|it| Some((it, it.expansion.as_ref()?.map_token_up(&token)?)))
+        {
+            result = frame.krate;
+
+            let site = match origin {
+                Origin::Def => frame.def_site,
+                Origin::Call => frame.call_site,
+            };
+
+            let site = match site {
+                None => break,
+                Some(it) => it,
+            };
+
+            current = Some(&self.0[site]);
+            token = mapped.value;
         }
+
+        result
     }
 }
diff --git a/crates/hir_expand/src/lib.rs b/crates/hir_expand/src/lib.rs
index 3fa1b1d77..5b6734a5f 100644
--- a/crates/hir_expand/src/lib.rs
+++ b/crates/hir_expand/src/lib.rs
@@ -340,11 +340,8 @@ impl ExpansionInfo {
         Some(self.expanded.with_value(token))
     }
 
-    pub fn map_token_up(
-        &self,
-        token: InFile<&SyntaxToken>,
-    ) -> Option<(InFile<SyntaxToken>, Origin)> {
-        let token_id = self.exp_map.token_by_range(token.value.text_range())?;
+    pub fn map_token_up(&self, token: &SyntaxToken) -> Option<(InFile<SyntaxToken>, Origin)> {
+        let token_id = self.exp_map.token_by_range(token.text_range())?;
 
         let (token_id, origin) = self.macro_def.0.map_id_up(token_id);
         let (token_map, tt) = match origin {
@@ -359,7 +356,7 @@ impl ExpansionInfo {
             ),
         };
 
-        let range = token_map.range_by_token(token_id)?.by_kind(token.value.kind())?;
+        let range = token_map.range_by_token(token_id)?.by_kind(token.kind())?;
         let token = algo::find_covering_element(&tt.value, range + tt.value.text_range().start())
             .into_token()?;
         Some((tt.with_value(token), origin))
@@ -495,7 +492,7 @@ fn ascend_call_token(
     expansion: &ExpansionInfo,
     token: InFile<SyntaxToken>,
 ) -> Option<InFile<SyntaxToken>> {
-    let (mapped, origin) = expansion.map_token_up(token.as_ref())?;
+    let (mapped, origin) = expansion.map_token_up(&token.value)?;
     if origin != Origin::Call {
         return None;
     }
diff --git a/crates/hir_ty/src/tests/macros.rs b/crates/hir_ty/src/tests/macros.rs
index a7656b864..23b79abc4 100644
--- a/crates/hir_ty/src/tests/macros.rs
+++ b/crates/hir_ty/src/tests/macros.rs
@@ -371,6 +371,37 @@ expand!();
 }
 
 #[test]
+fn infer_macro_with_dollar_crate_in_def_site() {
+    check_types(
+        r#"
+//- /main.rs crate:main deps:foo
+use foo::expand;
+
+macro_rules! list {
+    ($($tt:tt)*) => { $($tt)* }
+}
+
+fn test() {
+    let r = expand!();
+    r;
+  //^ u128
+}
+
+//- /lib.rs crate:foo
+#[macro_export]
+macro_rules! expand {
+    () => { list!($crate::m!()) };
+}
+
+#[macro_export]
+macro_rules! m {
+    () => { 0u128 };
+}
+"#,
+    );
+}
+
+#[test]
 fn infer_type_value_non_legacy_macro_use_as() {
     check_infer(
         r#"
diff --git a/crates/mbe/src/mbe_expander/matcher.rs b/crates/mbe/src/mbe_expander/matcher.rs
index ab5f87c48..385b46601 100644
--- a/crates/mbe/src/mbe_expander/matcher.rs
+++ b/crates/mbe/src/mbe_expander/matcher.rs
@@ -150,7 +150,7 @@ fn match_subtree(
                     res.add_err(err!("leftover tokens"));
                 }
             }
-            Op::Var { name, kind } => {
+            Op::Var { name, kind, .. } => {
                 let kind = match kind {
                     Some(k) => k,
                     None => {
diff --git a/crates/mbe/src/mbe_expander/transcriber.rs b/crates/mbe/src/mbe_expander/transcriber.rs
index 720531237..57f3f104d 100644
--- a/crates/mbe/src/mbe_expander/transcriber.rs
+++ b/crates/mbe/src/mbe_expander/transcriber.rs
@@ -100,8 +100,8 @@ fn expand_subtree(
                 err = err.or(e);
                 arena.push(tt.into());
             }
-            Op::Var { name, .. } => {
-                let ExpandResult { value: fragment, err: e } = expand_var(ctx, &name);
+            Op::Var { name, id, .. } => {
+                let ExpandResult { value: fragment, err: e } = expand_var(ctx, &name, *id);
                 err = err.or(e);
                 push_fragment(arena, fragment);
             }
@@ -118,12 +118,10 @@ fn expand_subtree(
     ExpandResult { value: tt::Subtree { delimiter: template.delimiter, token_trees: tts }, err }
 }
 
-fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr) -> ExpandResult<Fragment> {
+fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr, id: tt::TokenId) -> ExpandResult<Fragment> {
     if v == "crate" {
         // We simply produce identifier `$crate` here. And it will be resolved when lowering ast to Path.
-        let tt =
-            tt::Leaf::from(tt::Ident { text: "$crate".into(), id: tt::TokenId::unspecified() })
-                .into();
+        let tt = tt::Leaf::from(tt::Ident { text: "$crate".into(), id }).into();
         ExpandResult::ok(Fragment::Tokens(tt))
     } else if !ctx.bindings.contains(v) {
         // Note that it is possible to have a `$var` inside a macro which is not bound.
@@ -142,14 +140,8 @@ fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr) -> ExpandResult<Fragment> {
         let tt = tt::Subtree {
             delimiter: None,
             token_trees: vec![
-                tt::Leaf::from(tt::Punct {
-                    char: '$',
-                    spacing: tt::Spacing::Alone,
-                    id: tt::TokenId::unspecified(),
-                })
-                .into(),
-                tt::Leaf::from(tt::Ident { text: v.clone(), id: tt::TokenId::unspecified() })
-                    .into(),
+                tt::Leaf::from(tt::Punct { char: '$', spacing: tt::Spacing::Alone, id }).into(),
+                tt::Leaf::from(tt::Ident { text: v.clone(), id }).into(),
             ],
         }
         .into();
diff --git a/crates/mbe/src/parser.rs b/crates/mbe/src/parser.rs
index 2f3ebc831..77cc739b6 100644
--- a/crates/mbe/src/parser.rs
+++ b/crates/mbe/src/parser.rs
@@ -8,7 +8,7 @@ use crate::{tt_iter::TtIter, ExpandError, MetaTemplate};
 
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub(crate) enum Op {
-    Var { name: SmolStr, kind: Option<SmolStr> },
+    Var { name: SmolStr, kind: Option<SmolStr>, id: tt::TokenId },
     Repeat { subtree: MetaTemplate, kind: RepeatKind, separator: Option<Separator> },
     Leaf(tt::Leaf),
     Subtree(MetaTemplate),
@@ -106,18 +106,21 @@ fn next_op<'a>(first: &tt::TokenTree, src: &mut TtIter<'a>, mode: Mode) -> Resul
                         }
                         let name = UNDERSCORE.clone();
                         let kind = eat_fragment_kind(src, mode)?;
-                        Op::Var { name, kind }
+                        let id = punct.id;
+                        Op::Var { name, kind, id }
                     }
                     tt::Leaf::Ident(ident) => {
                         let name = ident.text.clone();
                         let kind = eat_fragment_kind(src, mode)?;
-                        Op::Var { name, kind }
+                        let id = ident.id;
+                        Op::Var { name, kind, id }
                     }
                     tt::Leaf::Literal(lit) => {
                         if is_boolean_literal(&lit) {
                             let name = lit.text.clone();
                             let kind = eat_fragment_kind(src, mode)?;
-                            Op::Var { name, kind }
+                            let id = lit.id;
+                            Op::Var { name, kind, id }
                         } else {
                             bail!("bad var 2");
                         }