4 files changed, 24 insertions, 52 deletions

diff --git a/crates/hir/src/display.rs b/crates/hir/src/display.rs
index 508ac37c2..c5cf803fd 100644
--- a/crates/hir/src/display.rs
+++ b/crates/hir/src/display.rs
@@ -92,7 +92,7 @@ impl HirDisplay for Function {
             &data.ret_type
         } else {
             match &*data.ret_type {
-                TypeRef::ImplTrait(bounds) => match &bounds[0] {
+                TypeRef::ImplTrait(bounds) => match bounds[0].as_ref() {
                     TypeBound::Path(path) => {
                         path.segments().iter().last().unwrap().args_and_bindings.unwrap().bindings
                             [0]
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index a7c42ca1e..cdf65a044 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -513,9 +513,8 @@ impl Field {
     }
 
     /// Returns the type as in the signature of the struct (i.e., with
-    /// placeholder types for type parameters). This is good for showing
-    /// signature help, but not so good to actually get the type of the field
-    /// when you actually have a variable of the struct.
+    /// placeholder types for type parameters). Only use this in the context of
+    /// the field definition.
     pub fn ty(&self, db: &dyn HirDatabase) -> Type {
         let var_id = self.parent.into();
         let generic_def_id: GenericDefId = match self.parent {
@@ -552,10 +551,6 @@ impl Struct {
         Module { id: self.id.lookup(db.upcast()).container }
     }
 
-    pub fn krate(self, db: &dyn HirDatabase) -> Option<Crate> {
-        Some(self.module(db).krate())
-    }
-
     pub fn name(self, db: &dyn HirDatabase) -> Name {
         db.struct_data(self.id).name.clone()
     }
@@ -640,10 +635,6 @@ impl Enum {
         Module { id: self.id.lookup(db.upcast()).container }
     }
 
-    pub fn krate(self, db: &dyn HirDatabase) -> Option<Crate> {
-        Some(self.module(db).krate())
-    }
-
     pub fn name(self, db: &dyn HirDatabase) -> Name {
         db.enum_data(self.id).name.clone()
     }
@@ -673,6 +664,7 @@ impl Variant {
     pub fn module(self, db: &dyn HirDatabase) -> Module {
         self.parent.module(db)
     }
+
     pub fn parent_enum(self, _db: &dyn HirDatabase) -> Enum {
         self.parent
     }
@@ -729,10 +721,6 @@ impl Adt {
         }
     }
 
-    pub fn krate(self, db: &dyn HirDatabase) -> Crate {
-        self.module(db).krate()
-    }
-
     pub fn name(self, db: &dyn HirDatabase) -> Name {
         match self {
             Adt::Struct(s) => s.name(db),
@@ -821,10 +809,6 @@ impl Function {
         self.id.lookup(db.upcast()).module(db.upcast()).into()
     }
 
-    pub fn krate(self, db: &dyn HirDatabase) -> Option<Crate> {
-        Some(self.module(db).krate())
-    }
-
     pub fn name(self, db: &dyn HirDatabase) -> Name {
         db.function_data(self.id).name.clone()
     }
@@ -1014,10 +998,6 @@ impl Const {
         Module { id: self.id.lookup(db.upcast()).module(db.upcast()) }
     }
 
-    pub fn krate(self, db: &dyn HirDatabase) -> Option<Crate> {
-        Some(self.module(db).krate())
-    }
-
     pub fn name(self, db: &dyn HirDatabase) -> Option<Name> {
         db.const_data(self.id).name.clone()
     }
@@ -1045,10 +1025,6 @@ impl Static {
         Module { id: self.id.lookup(db.upcast()).module(db.upcast()) }
     }
 
-    pub fn krate(self, db: &dyn HirDatabase) -> Option<Crate> {
-        Some(self.module(db).krate())
-    }
-
     pub fn name(self, db: &dyn HirDatabase) -> Option<Name> {
         db.static_data(self.id).name.clone()
     }
@@ -1112,10 +1088,6 @@ impl TypeAlias {
         Module { id: self.id.lookup(db.upcast()).module(db.upcast()) }
     }
 
-    pub fn krate(self, db: &dyn HirDatabase) -> Crate {
-        self.module(db).krate()
-    }
-
     pub fn type_ref(self, db: &dyn HirDatabase) -> Option<TypeRef> {
         db.type_alias_data(self.id).type_ref.as_deref().cloned()
     }
@@ -1667,10 +1639,6 @@ impl Impl {
         self.id.lookup(db.upcast()).container.into()
     }
 
-    pub fn krate(self, db: &dyn HirDatabase) -> Crate {
-        Crate { id: self.module(db).id.krate() }
-    }
-
     pub fn is_builtin_derive(self, db: &dyn HirDatabase) -> Option<InFile<ast::Attr>> {
         let src = self.source(db)?;
         let item = src.file_id.is_builtin_derive(db.upcast())?;
diff --git a/crates/hir/src/semantics.rs b/crates/hir/src/semantics.rs
index 1b5064b5a..8d3c43d08 100644
--- a/crates/hir/src/semantics.rs
+++ b/crates/hir/src/semantics.rs
@@ -11,7 +11,7 @@ use hir_def::{
     AsMacroCall, FunctionId, TraitId, VariantId,
 };
 use hir_expand::{name::AsName, ExpansionInfo};
-use hir_ty::associated_type_shorthand_candidates;
+use hir_ty::{associated_type_shorthand_candidates, Interner};
 use itertools::Itertools;
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::{
@@ -120,10 +120,10 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
     pub fn speculative_expand(
         &self,
         actual_macro_call: &ast::MacroCall,
-        hypothetical_args: &ast::TokenTree,
+        speculative_args: &ast::TokenTree,
         token_to_map: SyntaxToken,
     ) -> Option<(SyntaxNode, SyntaxToken)> {
-        self.imp.speculative_expand(actual_macro_call, hypothetical_args, token_to_map)
+        self.imp.speculative_expand(actual_macro_call, speculative_args, token_to_map)
     }
 
     pub fn descend_into_macros(&self, token: SyntaxToken) -> SyntaxToken {
@@ -227,7 +227,7 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
     pub fn resolve_record_field(
         &self,
         field: &ast::RecordExprField,
-    ) -> Option<(Field, Option<Local>)> {
+    ) -> Option<(Field, Option<Local>, Type)> {
         self.imp.resolve_record_field(field)
     }
 
@@ -335,7 +335,7 @@ impl<'db> SemanticsImpl<'db> {
     fn speculative_expand(
         &self,
         actual_macro_call: &ast::MacroCall,
-        hypothetical_args: &ast::TokenTree,
+        speculative_args: &ast::TokenTree,
         token_to_map: SyntaxToken,
     ) -> Option<(SyntaxNode, SyntaxToken)> {
         let sa = self.analyze(actual_macro_call.syntax());
@@ -344,10 +344,10 @@ impl<'db> SemanticsImpl<'db> {
         let macro_call_id = macro_call.as_call_id(self.db.upcast(), krate, |path| {
             sa.resolver.resolve_path_as_macro(self.db.upcast(), &path)
         })?;
-        hir_expand::db::expand_hypothetical(
+        hir_expand::db::expand_speculative(
             self.db.upcast(),
             macro_call_id,
-            hypothetical_args,
+            speculative_args,
             token_to_map,
         )
     }
@@ -501,14 +501,12 @@ impl<'db> SemanticsImpl<'db> {
     }
 
     fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<FunctionId> {
-        self.analyze(call.syntax()).resolve_method_call(self.db, call)
+        self.analyze(call.syntax()).resolve_method_call(self.db, call).map(|(id, _)| id)
     }
 
     fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
-        // FIXME: this erases Substs, we should instead record the correct
-        // substitution during inference and use that
-        let func = self.resolve_method_call(call)?;
-        let ty = hir_ty::TyBuilder::value_ty(self.db, func.into()).fill_with_unknown().build();
+        let (func, subst) = self.analyze(call.syntax()).resolve_method_call(self.db, call)?;
+        let ty = self.db.value_ty(func.into()).substitute(&Interner, &subst);
         let resolver = self.analyze(call.syntax()).resolver;
         let ty = Type::new_with_resolver(self.db, &resolver, ty)?;
         let mut res = ty.as_callable(self.db)?;
@@ -520,7 +518,10 @@ impl<'db> SemanticsImpl<'db> {
         self.analyze(field.syntax()).resolve_field(self.db, field)
     }
 
-    fn resolve_record_field(&self, field: &ast::RecordExprField) -> Option<(Field, Option<Local>)> {
+    fn resolve_record_field(
+        &self,
+        field: &ast::RecordExprField,
+    ) -> Option<(Field, Option<Local>, Type)> {
         self.analyze(field.syntax()).resolve_record_field(self.db, field)
     }
 
diff --git a/crates/hir/src/source_analyzer.rs b/crates/hir/src/source_analyzer.rs
index 20753314d..3f940124c 100644
--- a/crates/hir/src/source_analyzer.rs
+++ b/crates/hir/src/source_analyzer.rs
@@ -143,7 +143,7 @@ impl SourceAnalyzer {
         &self,
         db: &dyn HirDatabase,
         call: &ast::MethodCallExpr,
-    ) -> Option<FunctionId> {
+    ) -> Option<(FunctionId, Substitution)> {
         let expr_id = self.expr_id(db, &call.clone().into())?;
         self.infer.as_ref()?.method_resolution(expr_id)
     }
@@ -161,7 +161,7 @@ impl SourceAnalyzer {
         &self,
         db: &dyn HirDatabase,
         field: &ast::RecordExprField,
-    ) -> Option<(Field, Option<Local>)> {
+    ) -> Option<(Field, Option<Local>, Type)> {
         let record_expr = ast::RecordExpr::cast(field.syntax().parent().and_then(|p| p.parent())?)?;
         let expr = ast::Expr::from(record_expr);
         let expr_id = self.body_source_map.as_ref()?.node_expr(InFile::new(self.file_id, &expr))?;
@@ -178,10 +178,13 @@ impl SourceAnalyzer {
                 _ => None,
             }
         };
+        let (_, subst) = self.infer.as_ref()?.type_of_expr.get(expr_id)?.as_adt()?;
         let variant = self.infer.as_ref()?.variant_resolution_for_expr(expr_id)?;
         let variant_data = variant.variant_data(db.upcast());
         let field = FieldId { parent: variant, local_id: variant_data.field(&local_name)? };
-        Some((field.into(), local))
+        let field_ty =
+            db.field_types(variant).get(field.local_id)?.clone().substitute(&Interner, subst);
+        Some((field.into(), local, Type::new_with_resolver(db, &self.resolver, field_ty)?))
     }
 
     pub(crate) fn resolve_record_pat_field(