diff --git a/crates/hir-def/src/generics.rs b/crates/hir-def/src/generics.rs
index 0d95d916ff9..f5324f052e5 100644
--- a/crates/hir-def/src/generics.rs
+++ b/crates/hir-def/src/generics.rs
@@ -222,11 +222,10 @@ impl GenericParams {
                 let module = loc.container.module(db);
                 let func_data = db.function_data(id);
 
-                // Don't create an `Expander` nor call `loc.source(db)` if not needed since this
-                // causes a reparse after the `ItemTree` has been created.
-                let mut expander = Lazy::new(|| {
-                    (module.def_map(db), Expander::new(db, loc.source(db).file_id, module))
-                });
+                // Don't create an `Expander` if not needed since this
+                // could cause a reparse after the `ItemTree` has been created due to the spanmap.
+                let mut expander =
+                    Lazy::new(|| (module.def_map(db), Expander::new(db, loc.id.file_id(), module)));
                 for param in func_data.params.iter() {
                     generic_params.fill_implicit_impl_trait_args(db, &mut expander, param);
                 }
diff --git a/crates/hir-def/src/item_tree.rs b/crates/hir-def/src/item_tree.rs
index 16144394e3b..3d2cddffa3b 100644
--- a/crates/hir-def/src/item_tree.rs
+++ b/crates/hir-def/src/item_tree.rs
@@ -106,11 +106,6 @@ impl ItemTree {
     pub(crate) fn file_item_tree_query(db: &dyn DefDatabase, file_id: HirFileId) -> Arc<ItemTree> {
         let _p = profile::span("file_item_tree_query").detail(|| format!("{file_id:?}"));
         let syntax = db.parse_or_expand(file_id);
-        if never!(syntax.kind() == SyntaxKind::ERROR, "{:?} from {:?} {}", file_id, syntax, syntax)
-        {
-            // FIXME: not 100% sure why these crop up, but return an empty tree to avoid a panic
-            return Default::default();
-        }
 
         let ctx = lower::Ctx::new(db, file_id);
         let mut top_attrs = None;
@@ -129,6 +124,9 @@ impl ItemTree {
                     ctx.lower_macro_stmts(stmts)
                 },
                 _ => {
+                    if never!(syntax.kind() == SyntaxKind::ERROR, "{:?} from {:?} {}", file_id, syntax, syntax) {
+                        return Default::default();
+                    }
                     panic!("cannot create item tree for file {file_id:?} from {syntax:?} {syntax}");
                 },
             }
diff --git a/crates/hir-def/src/lib.rs b/crates/hir-def/src/lib.rs
index 7cf13a202e0..b5333861cc8 100644
--- a/crates/hir-def/src/lib.rs
+++ b/crates/hir-def/src/lib.rs
@@ -569,6 +569,8 @@ pub struct ConstBlockLoc {
     pub root: hir::ExprId,
 }
 
+/// Something that holds types, required for the current const arg lowering implementation as they
+/// need to be able to query where they are defined.
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
 pub enum TypeOwnerId {
     FunctionId(FunctionId),
@@ -581,9 +583,6 @@ pub enum TypeOwnerId {
     TypeAliasId(TypeAliasId),
     ImplId(ImplId),
     EnumVariantId(EnumVariantId),
-    // FIXME(const-generic-body): ModuleId should not be a type owner. This needs to be fixed to make `TypeOwnerId` actually
-    // useful for assigning ids to in type consts.
-    ModuleId(ModuleId),
 }
 
 impl TypeOwnerId {
@@ -597,9 +596,7 @@ impl TypeOwnerId {
             TypeOwnerId::TypeAliasId(it) => GenericDefId::TypeAliasId(it),
             TypeOwnerId::ImplId(it) => GenericDefId::ImplId(it),
             TypeOwnerId::EnumVariantId(it) => GenericDefId::EnumVariantId(it),
-            TypeOwnerId::InTypeConstId(_) | TypeOwnerId::ModuleId(_) | TypeOwnerId::StaticId(_) => {
-                return None
-            }
+            TypeOwnerId::InTypeConstId(_) | TypeOwnerId::StaticId(_) => return None,
         })
     }
 }
@@ -614,8 +611,7 @@ impl_from!(
     TraitAliasId,
     TypeAliasId,
     ImplId,
-    EnumVariantId,
-    ModuleId
+    EnumVariantId
     for TypeOwnerId
 );
 
@@ -713,12 +709,15 @@ pub struct InTypeConstLoc {
     pub id: AstId<ast::ConstArg>,
     /// The thing this const arg appears in
     pub owner: TypeOwnerId,
-    pub thing: Box<dyn OpaqueInternableThing>,
+    // FIXME(const-generic-body): The expected type should not be
+    pub expected_ty: Box<dyn OpaqueInternableThing>,
 }
 
 impl PartialEq for InTypeConstLoc {
     fn eq(&self, other: &Self) -> bool {
-        self.id == other.id && self.owner == other.owner && &*self.thing == &*other.thing
+        self.id == other.id
+            && self.owner == other.owner
+            && &*self.expected_ty == &*other.expected_ty
     }
 }
 
@@ -1041,7 +1040,6 @@ impl HasModule for TypeOwnerId {
             TypeOwnerId::TypeAliasId(it) => it.lookup(db).module(db),
             TypeOwnerId::ImplId(it) => it.lookup(db).container,
             TypeOwnerId::EnumVariantId(it) => it.parent.lookup(db).container,
-            TypeOwnerId::ModuleId(it) => *it,
         }
     }
 }
diff --git a/crates/hir-def/src/resolver.rs b/crates/hir-def/src/resolver.rs
index ba0a2c0224a..2ac1516ec07 100644
--- a/crates/hir-def/src/resolver.rs
+++ b/crates/hir-def/src/resolver.rs
@@ -589,6 +589,16 @@ impl Resolver {
         })
     }
 
+    pub fn type_owner(&self) -> Option<TypeOwnerId> {
+        self.scopes().find_map(|scope| match scope {
+            Scope::BlockScope(_) => None,
+            &Scope::GenericParams { def, .. } => Some(def.into()),
+            &Scope::ImplDefScope(id) => Some(id.into()),
+            &Scope::AdtScope(adt) => Some(adt.into()),
+            Scope::ExprScope(it) => Some(it.owner.into()),
+        })
+    }
+
     pub fn impl_def(&self) -> Option<ImplId> {
         self.scopes().find_map(|scope| match scope {
             Scope::ImplDefScope(def) => Some(*def),
@@ -1079,7 +1089,6 @@ impl HasResolver for TypeOwnerId {
             TypeOwnerId::TypeAliasId(it) => it.resolver(db),
             TypeOwnerId::ImplId(it) => it.resolver(db),
             TypeOwnerId::EnumVariantId(it) => it.resolver(db),
-            TypeOwnerId::ModuleId(it) => it.resolver(db),
         }
     }
 }
diff --git a/crates/hir-expand/src/eager.rs b/crates/hir-expand/src/eager.rs
index 1e2722e8464..8d55240aef5 100644
--- a/crates/hir-expand/src/eager.rs
+++ b/crates/hir-expand/src/eager.rs
@@ -88,7 +88,7 @@ pub fn expand_eager_macro_input(
     let loc = MacroCallLoc {
         def,
         krate,
-        eager: Some(Box::new(EagerCallInfo { arg: Arc::new(subtree), arg_id, error: err.clone() })),
+        eager: Some(Arc::new(EagerCallInfo { arg: Arc::new(subtree), arg_id, error: err.clone() })),
         kind: MacroCallKind::FnLike { ast_id: call_id, expand_to },
         call_site,
     };
diff --git a/crates/hir-expand/src/lib.rs b/crates/hir-expand/src/lib.rs
index f5e9cd33f2b..d7819b315c4 100644
--- a/crates/hir-expand/src/lib.rs
+++ b/crates/hir-expand/src/lib.rs
@@ -117,7 +117,7 @@ pub struct MacroCallLoc {
     pub krate: CrateId,
     /// Some if this is a macro call for an eager macro. Note that this is `None`
     /// for the eager input macro file.
-    eager: Option<Box<EagerCallInfo>>,
+    eager: Option<Arc<EagerCallInfo>>,
     pub kind: MacroCallKind,
     pub call_site: SyntaxContextId,
 }
diff --git a/crates/hir-ty/src/infer.rs b/crates/hir-ty/src/infer.rs
index 8262edec22c..6f724e45874 100644
--- a/crates/hir-ty/src/infer.rs
+++ b/crates/hir-ty/src/infer.rs
@@ -113,7 +113,7 @@ pub(crate) fn infer_query(db: &dyn HirDatabase, def: DefWithBodyId) -> Arc<Infer
             // FIXME(const-generic-body): We should not get the return type in this way.
             ctx.return_ty = c
                 .lookup(db.upcast())
-                .thing
+                .expected_ty
                 .box_any()
                 .downcast::<InTypeConstIdMetadata>()
                 .unwrap()
diff --git a/crates/hir-ty/src/lower.rs b/crates/hir-ty/src/lower.rs
index c86fe9adff8..97c4a741ff2 100644
--- a/crates/hir-ty/src/lower.rs
+++ b/crates/hir-ty/src/lower.rs
@@ -113,7 +113,9 @@ pub struct TyLoweringContext<'a> {
     pub db: &'a dyn HirDatabase,
     resolver: &'a Resolver,
     in_binders: DebruijnIndex,
-    owner: TypeOwnerId,
+    // FIXME: Should not be an `Option` but `Resolver` currently does not return owners in all cases
+    // where expected
+    owner: Option<TypeOwnerId>,
     /// Note: Conceptually, it's thinkable that we could be in a location where
     /// some type params should be represented as placeholders, and others
     /// should be converted to variables. I think in practice, this isn't
@@ -127,6 +129,14 @@ pub struct TyLoweringContext<'a> {
 
 impl<'a> TyLoweringContext<'a> {
     pub fn new(db: &'a dyn HirDatabase, resolver: &'a Resolver, owner: TypeOwnerId) -> Self {
+        Self::new_maybe_unowned(db, resolver, Some(owner))
+    }
+
+    pub fn new_maybe_unowned(
+        db: &'a dyn HirDatabase,
+        resolver: &'a Resolver,
+        owner: Option<TypeOwnerId>,
+    ) -> Self {
         let impl_trait_mode = ImplTraitLoweringState::Disallowed;
         let type_param_mode = ParamLoweringMode::Placeholder;
         let in_binders = DebruijnIndex::INNERMOST;
@@ -213,10 +223,11 @@ impl<'a> TyLoweringContext<'a> {
     }
 
     pub fn lower_const(&self, const_ref: &ConstRef, const_type: Ty) -> Const {
+        let Some(owner) = self.owner else { return unknown_const(const_type) };
         const_or_path_to_chalk(
             self.db,
             self.resolver,
-            self.owner,
+            owner,
             const_type,
             const_ref,
             self.type_param_mode,
@@ -1768,10 +1779,11 @@ fn type_for_type_alias(db: &dyn HirDatabase, t: TypeAliasId) -> Binders<Ty> {
     let resolver = t.resolver(db.upcast());
     let ctx = TyLoweringContext::new(db, &resolver, t.into())
         .with_type_param_mode(ParamLoweringMode::Variable);
-    if db.type_alias_data(t).is_extern {
+    let type_alias_data = db.type_alias_data(t);
+    if type_alias_data.is_extern {
         Binders::empty(Interner, TyKind::Foreign(crate::to_foreign_def_id(t)).intern(Interner))
     } else {
-        let type_ref = &db.type_alias_data(t).type_ref;
+        let type_ref = &type_alias_data.type_ref;
         let inner = ctx.lower_ty(type_ref.as_deref().unwrap_or(&TypeRef::Error));
         make_binders(db, &generics, inner)
     }
@@ -2042,7 +2054,7 @@ pub(crate) fn const_or_path_to_chalk(
                 .intern_in_type_const(InTypeConstLoc {
                     id: it,
                     owner,
-                    thing: Box::new(InTypeConstIdMetadata(expected_ty.clone())),
+                    expected_ty: Box::new(InTypeConstIdMetadata(expected_ty.clone())),
                 })
                 .into();
             intern_const_scalar(
diff --git a/crates/hir-ty/src/tests/incremental.rs b/crates/hir-ty/src/tests/incremental.rs
index bb15ca8c436..28e84e480d7 100644
--- a/crates/hir-ty/src/tests/incremental.rs
+++ b/crates/hir-ty/src/tests/incremental.rs
@@ -9,11 +9,10 @@ use super::visit_module;
 fn typing_whitespace_inside_a_function_should_not_invalidate_types() {
     let (mut db, pos) = TestDB::with_position(
         "
-        //- /lib.rs
-        fn foo() -> i32 {
-            $01 + 1
-        }
-    ",
+//- /lib.rs
+fn foo() -> i32 {
+    $01 + 1
+}",
     );
     {
         let events = db.log_executed(|| {
@@ -27,12 +26,11 @@ fn typing_whitespace_inside_a_function_should_not_invalidate_types() {
     }
 
     let new_text = "
-        fn foo() -> i32 {
-            1
-            +
-            1
-        }
-    ";
+fn foo() -> i32 {
+    1
+    +
+    1
+}";
 
     db.set_file_text(pos.file_id, Arc::from(new_text));
 
@@ -47,3 +45,55 @@ fn typing_whitespace_inside_a_function_should_not_invalidate_types() {
         assert!(!format!("{events:?}").contains("infer"), "{events:#?}")
     }
 }
+
+#[test]
+fn typing_inside_a_function_should_not_invalidate_types_in_another() {
+    let (mut db, pos) = TestDB::with_position(
+        "
+//- /lib.rs
+fn foo() -> f32 {
+    1.0 + 2.0
+}
+fn bar() -> i32 {
+    $01 + 1
+}
+fn baz() -> i32 {
+    1 + 1
+}",
+    );
+    {
+        let events = db.log_executed(|| {
+            let module = db.module_for_file(pos.file_id);
+            let crate_def_map = module.def_map(&db);
+            visit_module(&db, &crate_def_map, module.local_id, &mut |def| {
+                db.infer(def);
+            });
+        });
+        assert!(format!("{events:?}").contains("infer"))
+    }
+
+    let new_text = "
+fn foo() -> f32 {
+    1.0 + 2.0
+}
+fn bar() -> i32 {
+    53
+}
+fn baz() -> i32 {
+    1 + 1
+}
+";
+
+    db.set_file_text(pos.file_id, Arc::from(new_text));
+
+    {
+        let events = db.log_executed(|| {
+            let module = db.module_for_file(pos.file_id);
+            let crate_def_map = module.def_map(&db);
+            visit_module(&db, &crate_def_map, module.local_id, &mut |def| {
+                db.infer(def);
+            });
+        });
+        assert!(format!("{events:?}").matches("infer").count() == 1, "{events:#?}")
+    }
+}
diff --git a/crates/hir/src/semantics.rs b/crates/hir/src/semantics.rs
index dcf8ba27a68..a03ff220745 100644
--- a/crates/hir/src/semantics.rs
+++ b/crates/hir/src/semantics.rs
@@ -948,10 +948,10 @@ impl<'db> SemanticsImpl<'db> {
     pub fn resolve_type(&self, ty: &ast::Type) -> Option<Type> {
         let analyze = self.analyze(ty.syntax())?;
         let ctx = LowerCtx::with_file_id(self.db.upcast(), analyze.file_id);
-        let ty = hir_ty::TyLoweringContext::new(
+        let ty = hir_ty::TyLoweringContext::new_maybe_unowned(
             self.db,
             &analyze.resolver,
-            analyze.resolver.module().into(),
+            analyze.resolver.type_owner(),
         )
         .lower_ty(&crate::TypeRef::from_ast(&ctx, ty.clone()));
         Some(Type::new_with_resolver(self.db, &analyze.resolver, ty))
diff --git a/crates/hir/src/source_analyzer.rs b/crates/hir/src/source_analyzer.rs
index 73db6f8f0b8..d05118bbc28 100644
--- a/crates/hir/src/source_analyzer.rs
+++ b/crates/hir/src/source_analyzer.rs
@@ -1040,8 +1040,9 @@ fn resolve_hir_path_(
     let types = || {
         let (ty, unresolved) = match path.type_anchor() {
             Some(type_ref) => {
-                let (_, res) = TyLoweringContext::new(db, resolver, resolver.module().into())
-                    .lower_ty_ext(type_ref);
+                let (_, res) =
+                    TyLoweringContext::new_maybe_unowned(db, resolver, resolver.type_owner())
+                        .lower_ty_ext(type_ref);
                 res.map(|ty_ns| (ty_ns, path.segments().first()))
             }
             None => {