Rollup merge of #64250 - Xanewok:save-analysis-assoc-nested, r=varkor

save-analysis: Nest typeck tables when processing functions/methods

Fixes an issue where we did not nest tables correctly when resolving
associated types in formal argument/return type positions.

This was the minimized reproduction case that I tested the fix on:
```rust
pub trait Trait {
    type Assoc;
}

pub struct A;

pub fn func() {
    fn _inner1<U: Trait>(_: U::Assoc) {}
    fn _inner2<U: Trait>() -> U::Assoc { unimplemented!() }

    impl A {
        fn _inner1<U: Trait>(self, _: U::Assoc) {}
        fn _inner2<U: Trait>(self) -> U::Assoc { unimplemented!() }
    }
}
```
using `debug_assertions`-enabled rustc and by additionally passing `-Zsave-analysis`.

Unfortunately the original assertion fired is a *debug* one and from what I can tell we don't run the tests with these on, so I'm not adding a test here. If I missed it and there is a way to run tests with these on, I'd love to add a test case for this.

Closes #63663
Closes #50328
Closes #43982

4 files changed, 113 insertions, 80 deletions

diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs
index 25d921b7cea..0155803e305 100644
--- a/src/librustc/ty/context.rs
+++ b/src/librustc/ty/context.rs
@@ -205,26 +205,24 @@ pub struct LocalTableInContext<'a, V> {
 fn validate_hir_id_for_typeck_tables(local_id_root: Option<DefId>,
                                      hir_id: hir::HirId,
                                      mut_access: bool) {
-    if cfg!(debug_assertions) {
-        if let Some(local_id_root) = local_id_root {
-            if hir_id.owner != local_id_root.index {
-                ty::tls::with(|tcx| {
-                    bug!("node {} with HirId::owner {:?} cannot be placed in \
-                          TypeckTables with local_id_root {:?}",
-                         tcx.hir().node_to_string(hir_id),
-                         DefId::local(hir_id.owner),
-                         local_id_root)
-                });
-            }
-        } else {
-            // We use "Null Object" TypeckTables in some of the analysis passes.
-            // These are just expected to be empty and their `local_id_root` is
-            // `None`. Therefore we cannot verify whether a given `HirId` would
-            // be a valid key for the given table. Instead we make sure that
-            // nobody tries to write to such a Null Object table.
-            if mut_access {
-                bug!("access to invalid TypeckTables")
-            }
+    if let Some(local_id_root) = local_id_root {
+        if hir_id.owner != local_id_root.index {
+            ty::tls::with(|tcx| {
+                bug!("node {} with HirId::owner {:?} cannot be placed in \
+                        TypeckTables with local_id_root {:?}",
+                        tcx.hir().node_to_string(hir_id),
+                        DefId::local(hir_id.owner),
+                        local_id_root)
+            });
+        }
+    } else {
+        // We use "Null Object" TypeckTables in some of the analysis passes.
+        // These are just expected to be empty and their `local_id_root` is
+        // `None`. Therefore we cannot verify whether a given `HirId` would
+        // be a valid key for the given table. Instead we make sure that
+        // nobody tries to write to such a Null Object table.
+        if mut_access {
+            bug!("access to invalid TypeckTables")
         }
     }
 }
diff --git a/src/librustc_save_analysis/dump_visitor.rs b/src/librustc_save_analysis/dump_visitor.rs
index 12c5ce12a0e..55f6b91e714 100644
--- a/src/librustc_save_analysis/dump_visitor.rs
+++ b/src/librustc_save_analysis/dump_visitor.rs
@@ -130,6 +130,10 @@ impl<'l, 'tcx> DumpVisitor<'l, 'tcx> {
         self.save_ctxt.span_from_span(span)
     }
 
+    fn lookup_def_id(&self, ref_id: NodeId) -> Option<DefId> {
+        self.save_ctxt.lookup_def_id(ref_id)
+    }
+
     pub fn dump_crate_info(&mut self, name: &str, krate: &ast::Crate) {
         let source_file = self.tcx.sess.local_crate_source_file.as_ref();
         let crate_root = source_file.map(|source_file| {
@@ -223,13 +227,6 @@ impl<'l, 'tcx> DumpVisitor<'l, 'tcx> {
         }
     }
 
-    fn lookup_def_id(&self, ref_id: NodeId) -> Option<DefId> {
-        match self.save_ctxt.get_path_res(ref_id) {
-            Res::PrimTy(..) | Res::SelfTy(..) | Res::Err => None,
-            def => Some(def.def_id()),
-        }
-    }
-
     fn process_formals(&mut self, formals: &'l [ast::Param], qualname: &str) {
         for arg in formals {
             self.visit_pat(&arg.pat);
@@ -283,36 +280,32 @@ impl<'l, 'tcx> DumpVisitor<'l, 'tcx> {
     ) {
         debug!("process_method: {}:{}", id, ident);
 
-        if let Some(mut method_data) = self.save_ctxt.get_method_data(id, ident, span) {
-            let sig_str = crate::make_signature(&sig.decl, &generics);
-            if body.is_some() {
-                self.nest_tables(
-                    id,
-                    |v| v.process_formals(&sig.decl.inputs, &method_data.qualname),
-                );
-            }
+        let hir_id = self.tcx.hir().node_to_hir_id(id);
+        self.nest_tables(id, |v| {
+            if let Some(mut method_data) = v.save_ctxt.get_method_data(id, ident, span) {
+                v.process_formals(&sig.decl.inputs, &method_data.qualname);
+                v.process_generic_params(&generics, &method_data.qualname, id);
 
-            self.process_generic_params(&generics, &method_data.qualname, id);
+                method_data.value = crate::make_signature(&sig.decl, &generics);
+                method_data.sig = sig::method_signature(id, ident, generics, sig, &v.save_ctxt);
 
-            method_data.value = sig_str;
-            method_data.sig = sig::method_signature(id, ident, generics, sig, &self.save_ctxt);
-            let hir_id = self.tcx.hir().node_to_hir_id(id);
-            self.dumper.dump_def(&access_from_vis!(self.save_ctxt, vis, hir_id), method_data);
-        }
+                v.dumper.dump_def(&access_from_vis!(v.save_ctxt, vis, hir_id), method_data);
+            }
 
-        // walk arg and return types
-        for arg in &sig.decl.inputs {
-            self.visit_ty(&arg.ty);
-        }
+            // walk arg and return types
+            for arg in &sig.decl.inputs {
+                v.visit_ty(&arg.ty);
+            }
 
-        if let ast::FunctionRetTy::Ty(ref ret_ty) = sig.decl.output {
-            self.visit_ty(ret_ty);
-        }
+            if let ast::FunctionRetTy::Ty(ref ret_ty) = sig.decl.output {
+                v.visit_ty(ret_ty);
+            }
 
-        // walk the fn body
-        if let Some(body) = body {
-            self.nest_tables(id, |v| v.visit_block(body));
-        }
+            // walk the fn body
+            if let Some(body) = body {
+                v.visit_block(body);
+            }
+        });
     }
 
     fn process_struct_field_def(&mut self, field: &ast::StructField, parent_id: NodeId) {
@@ -377,26 +370,31 @@ impl<'l, 'tcx> DumpVisitor<'l, 'tcx> {
         ty_params: &'l ast::Generics,
         body: &'l ast::Block,
     ) {
-        if let Some(fn_data) = self.save_ctxt.get_item_data(item) {
-            down_cast_data!(fn_data, DefData, item.span);
-            self.nest_tables(
-                item.id,
-                |v| v.process_formals(&decl.inputs, &fn_data.qualname),
-            );
-            self.process_generic_params(ty_params, &fn_data.qualname, item.id);
-            let hir_id = self.tcx.hir().node_to_hir_id(item.id);
-            self.dumper.dump_def(&access_from!(self.save_ctxt, item, hir_id), fn_data);
-        }
+        let hir_id = self.tcx.hir().node_to_hir_id(item.id);
+        self.nest_tables(item.id, |v| {
+            if let Some(fn_data) = v.save_ctxt.get_item_data(item) {
+                down_cast_data!(fn_data, DefData, item.span);
+                v.process_formals(&decl.inputs, &fn_data.qualname);
+                v.process_generic_params(ty_params, &fn_data.qualname, item.id);
 
-        for arg in &decl.inputs {
-            self.visit_ty(&arg.ty);
-        }
+                v.dumper.dump_def(&access_from!(v.save_ctxt, item, hir_id), fn_data);
+            }
 
-        if let ast::FunctionRetTy::Ty(ref ret_ty) = decl.output {
-            self.visit_ty(&ret_ty);
-        }
+            for arg in &decl.inputs {
+                v.visit_ty(&arg.ty)
+            }
+
+            if let ast::FunctionRetTy::Ty(ref ret_ty) = decl.output {
+                if let ast::TyKind::ImplTrait(..) = ret_ty.node {
+                    // FIXME: Opaque type desugaring prevents us from easily
+                    // processing trait bounds. See `visit_ty` for more details.
+                } else {
+                    v.visit_ty(&ret_ty);
+                }
+            }
 
-        self.nest_tables(item.id, |v| v.visit_block(&body));
+            v.visit_block(&body);
+        });
     }
 
     fn process_static_or_const_item(
@@ -1113,11 +1111,7 @@ impl<'l, 'tcx> DumpVisitor<'l, 'tcx> {
                 // FIXME: uses of the assoc type should ideally point to this
                 // 'def' and the name here should be a ref to the def in the
                 // trait.
-                for bound in bounds.iter() {
-                    if let ast::GenericBound::Trait(trait_ref, _) = bound {
-                        self.process_path(trait_ref.trait_ref.ref_id, &trait_ref.trait_ref.path)
-                    }
-                }
+                self.process_bounds(&bounds);
             }
             ast::ImplItemKind::Macro(_) => {}
         }
@@ -1364,10 +1358,10 @@ impl<'l, 'tcx> Visitor<'l> for DumpVisitor<'l, 'tcx> {
                 self.visit_ty(&ty);
                 self.process_generic_params(ty_params, &qualname, item.id);
             }
-            OpaqueTy(ref _bounds, ref ty_params) => {
+            OpaqueTy(ref bounds, ref ty_params) => {
                 let qualname = format!("::{}",
                     self.tcx.def_path_str(self.tcx.hir().local_def_id_from_node_id(item.id)));
-                // FIXME do something with _bounds
+
                 let value = String::new();
                 if !self.span.filter_generated(item.ident.span) {
                     let span = self.span_from_span(item.ident.span);
@@ -1393,6 +1387,7 @@ impl<'l, 'tcx> Visitor<'l> for DumpVisitor<'l, 'tcx> {
                     );
                 }
 
+                self.process_bounds(bounds);
                 self.process_generic_params(ty_params, &qualname, item.id);
             }
             Mac(_) => (),
@@ -1449,6 +1444,18 @@ impl<'l, 'tcx> Visitor<'l> for DumpVisitor<'l, 'tcx> {
                 self.visit_ty(element);
                 self.nest_tables(length.id, |v| v.visit_expr(&length.value));
             }
+            ast::TyKind::ImplTrait(id, ref bounds) => {
+                // FIXME: As of writing, the opaque type lowering introduces
+                // another DefPath scope/segment (used to declare the resulting
+                // opaque type item).
+                // However, the synthetic scope does *not* have associated
+                // typeck tables, which means we can't nest it and we fire an
+                // assertion when resolving the qualified type paths in trait
+                // bounds...
+                // This will panic if called on return type `impl Trait`, which
+                // we guard against in `process_fn`.
+                self.nest_tables(id, |v| v.process_bounds(bounds));
+            }
             _ => visit::walk_ty(self, t),
         }
     }
diff --git a/src/librustc_save_analysis/lib.rs b/src/librustc_save_analysis/lib.rs
index 4bc098db686..055ccf6c2c4 100644
--- a/src/librustc_save_analysis/lib.rs
+++ b/src/librustc_save_analysis/lib.rs
@@ -312,7 +312,7 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
                     let impl_id = self.next_impl_id();
                     let span = self.span_from_span(sub_span);
 
-                    let type_data = self.lookup_ref_id(typ.id);
+                    let type_data = self.lookup_def_id(typ.id);
                     type_data.map(|type_data| {
                         Data::RelationData(Relation {
                             kind: RelationKind::Impl {
@@ -322,7 +322,7 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
                             from: id_from_def_id(type_data),
                             to: trait_ref
                                 .as_ref()
-                                .and_then(|t| self.lookup_ref_id(t.ref_id))
+                                .and_then(|t| self.lookup_def_id(t.ref_id))
                                 .map(id_from_def_id)
                                 .unwrap_or_else(|| null_id()),
                         },
@@ -495,7 +495,7 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
     }
 
     pub fn get_trait_ref_data(&self, trait_ref: &ast::TraitRef) -> Option<Ref> {
-        self.lookup_ref_id(trait_ref.ref_id).and_then(|def_id| {
+        self.lookup_def_id(trait_ref.ref_id).and_then(|def_id| {
             let span = trait_ref.path.span;
             if generated_code(span) {
                 return None;
@@ -870,7 +870,7 @@ impl<'l, 'tcx> SaveContext<'l, 'tcx> {
         })
     }
 
-    fn lookup_ref_id(&self, ref_id: NodeId) -> Option<DefId> {
+    fn lookup_def_id(&self, ref_id: NodeId) -> Option<DefId> {
         match self.get_path_res(ref_id) {
             Res::PrimTy(_) | Res::SelfTy(..) | Res::Err => None,
             def => Some(def.def_id()),
diff --git a/src/test/ui/save-analysis/issue-63663.rs b/src/test/ui/save-analysis/issue-63663.rs
new file mode 100644
index 00000000000..92e85884f66
--- /dev/null
+++ b/src/test/ui/save-analysis/issue-63663.rs
@@ -0,0 +1,28 @@
+// check-pass
+// compile-flags: -Zsave-analysis
+
+pub trait Trait {
+    type Assoc;
+}
+
+pub struct A;
+
+trait Generic<T> {}
+impl<T> Generic<T> for () {}
+
+// Don't ICE when resolving type paths in return type `impl Trait`
+fn assoc_in_opaque_type_bounds<U: Trait>() -> impl Generic<U::Assoc> {}
+
+// Check that this doesn't ICE when processing associated const in formal
+// argument and return type of functions defined inside function/method scope.
+pub fn func() {
+    fn _inner1<U: Trait>(_: U::Assoc) {}
+    fn _inner2<U: Trait>() -> U::Assoc { unimplemented!() }
+
+    impl A {
+        fn _inner1<U: Trait>(self, _: U::Assoc) {}
+        fn _inner2<U: Trait>(self) -> U::Assoc { unimplemented!() }
+    }
+}
+
+fn main() {}