3 files changed, 98 insertions, 51 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index c6f3bdb8e..9baebf643 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -1027,8 +1027,16 @@ impl Type {
         ty: Ty,
     ) -> Option<Type> {
         let krate = resolver.krate()?;
+        Some(Type::new_with_resolver_inner(db, krate, resolver, ty))
+    }
+    pub(crate) fn new_with_resolver_inner(
+        db: &dyn HirDatabase,
+        krate: CrateId,
+        resolver: &Resolver,
+        ty: Ty,
+    ) -> Type {
         let environment = TraitEnvironment::lower(db, &resolver);
-        Some(Type { krate, ty: InEnvironment { value: ty, environment } })
+        Type { krate, ty: InEnvironment { value: ty, environment } }
     }
 
     fn new(db: &dyn HirDatabase, krate: CrateId, lexical_env: impl HasResolver, ty: Ty) -> Type {
@@ -1152,27 +1160,6 @@ impl Type {
         res
     }
 
-    pub fn variant_fields(
-        &self,
-        db: &dyn HirDatabase,
-        def: VariantDef,
-    ) -> Vec<(StructField, Type)> {
-        // FIXME: check that ty and def match
-        match &self.ty.value {
-            Ty::Apply(a_ty) => {
-                let field_types = db.field_types(def.into());
-                def.fields(db)
-                    .into_iter()
-                    .map(|it| {
-                        let ty = field_types[it.id].clone().subst(&a_ty.parameters);
-                        (it, self.derived(ty))
-                    })
-                    .collect()
-            }
-            _ => Vec::new(),
-        }
-    }
-
     pub fn autoderef<'a>(&'a self, db: &'a dyn HirDatabase) -> impl Iterator<Item = Type> + 'a {
         // There should be no inference vars in types passed here
         // FIXME check that?
diff --git a/crates/ra_hir/src/semantics.rs b/crates/ra_hir/src/semantics.rs
index 2ad231d36..2707e422d 100644
--- a/crates/ra_hir/src/semantics.rs
+++ b/crates/ra_hir/src/semantics.rs
@@ -23,7 +23,7 @@ use crate::{
     semantics::source_to_def::{ChildContainer, SourceToDefCache, SourceToDefCtx},
     source_analyzer::{resolve_hir_path, SourceAnalyzer},
     AssocItem, Function, HirFileId, ImplDef, InFile, Local, MacroDef, Module, ModuleDef, Name,
-    Origin, Path, ScopeDef, StructField, Trait, Type, TypeParam, VariantDef,
+    Origin, Path, ScopeDef, StructField, Trait, Type, TypeParam,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -187,14 +187,6 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.analyze(field.syntax()).resolve_record_field(self.db, field)
     }
 
-    pub fn resolve_record_literal(&self, record_lit: &ast::RecordLit) -> Option<VariantDef> {
-        self.analyze(record_lit.syntax()).resolve_record_literal(self.db, record_lit)
-    }
-
-    pub fn resolve_record_pattern(&self, record_pat: &ast::RecordPat) -> Option<VariantDef> {
-        self.analyze(record_pat.syntax()).resolve_record_pattern(record_pat)
-    }
-
     pub fn resolve_macro_call(&self, macro_call: &ast::MacroCall) -> Option<MacroDef> {
         let sa = self.analyze(macro_call.syntax());
         let macro_call = self.find_file(macro_call.syntax().clone()).with_value(macro_call);
@@ -212,6 +204,24 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
     // FIXME: use this instead?
     // pub fn resolve_name_ref(&self, name_ref: &ast::NameRef) -> Option<???>;
 
+    pub fn record_literal_missing_fields(
+        &self,
+        literal: &ast::RecordLit,
+    ) -> Vec<(StructField, Type)> {
+        self.analyze(literal.syntax())
+            .record_literal_missing_fields(self.db, literal)
+            .unwrap_or_default()
+    }
+
+    pub fn record_pattern_missing_fields(
+        &self,
+        pattern: &ast::RecordPat,
+    ) -> Vec<(StructField, Type)> {
+        self.analyze(pattern.syntax())
+            .record_pattern_missing_fields(self.db, pattern)
+            .unwrap_or_default()
+    }
+
     pub fn to_def<T: ToDef>(&self, src: &T) -> Option<T::Def> {
         let src = self.find_file(src.syntax().clone()).with_value(src).cloned();
         T::to_def(self, src)
diff --git a/crates/ra_hir/src/source_analyzer.rs b/crates/ra_hir/src/source_analyzer.rs
index 815ca158c..45631f8fd 100644
--- a/crates/ra_hir/src/source_analyzer.rs
+++ b/crates/ra_hir/src/source_analyzer.rs
@@ -14,10 +14,13 @@ use hir_def::{
     },
     expr::{ExprId, Pat, PatId},
     resolver::{resolver_for_scope, Resolver, TypeNs, ValueNs},
-    AsMacroCall, DefWithBodyId,
+    AsMacroCall, DefWithBodyId, LocalStructFieldId, StructFieldId, VariantId,
 };
 use hir_expand::{hygiene::Hygiene, name::AsName, HirFileId, InFile};
-use hir_ty::InferenceResult;
+use hir_ty::{
+    expr::{record_literal_missing_fields, record_pattern_missing_fields},
+    InferenceResult, Substs, Ty,
+};
 use ra_syntax::{
     ast::{self, AstNode},
     SyntaxNode, SyntaxNodePtr, TextUnit,
@@ -25,8 +28,10 @@ use ra_syntax::{
 
 use crate::{
     db::HirDatabase, semantics::PathResolution, Adt, Const, EnumVariant, Function, Local, MacroDef,
-    ModPath, ModuleDef, Path, PathKind, Static, Struct, Trait, Type, TypeAlias, TypeParam,
+    ModPath, ModuleDef, Path, PathKind, Static, Struct, StructField, Trait, Type, TypeAlias,
+    TypeParam,
 };
+use ra_db::CrateId;
 
 /// `SourceAnalyzer` is a convenience wrapper which exposes HIR API in terms of
 /// original source files. It should not be used inside the HIR itself.
@@ -164,23 +169,6 @@ impl SourceAnalyzer {
         Some((struct_field.into(), local))
     }
 
-    pub(crate) fn resolve_record_literal(
-        &self,
-        db: &dyn HirDatabase,
-        record_lit: &ast::RecordLit,
-    ) -> Option<crate::VariantDef> {
-        let expr_id = self.expr_id(db, &record_lit.clone().into())?;
-        self.infer.as_ref()?.variant_resolution_for_expr(expr_id).map(|it| it.into())
-    }
-
-    pub(crate) fn resolve_record_pattern(
-        &self,
-        record_pat: &ast::RecordPat,
-    ) -> Option<crate::VariantDef> {
-        let pat_id = self.pat_id(&record_pat.clone().into())?;
-        self.infer.as_ref()?.variant_resolution_for_pat(pat_id).map(|it| it.into())
-    }
-
     pub(crate) fn resolve_macro_call(
         &self,
         db: &dyn HirDatabase,
@@ -231,6 +219,68 @@ impl SourceAnalyzer {
         resolve_hir_path(db, &self.resolver, &hir_path)
     }
 
+    pub(crate) fn record_literal_missing_fields(
+        &self,
+        db: &dyn HirDatabase,
+        literal: &ast::RecordLit,
+    ) -> Option<Vec<(StructField, Type)>> {
+        let krate = self.resolver.krate()?;
+        let body = self.body.as_ref()?;
+        let infer = self.infer.as_ref()?;
+
+        let expr_id = self.expr_id(db, &literal.clone().into())?;
+        let substs = match &infer.type_of_expr[expr_id] {
+            Ty::Apply(a_ty) => &a_ty.parameters,
+            _ => return None,
+        };
+
+        let (variant, missing_fields, _exhaustive) =
+            record_literal_missing_fields(db, infer, expr_id, &body[expr_id])?;
+        let res = self.missing_fields(db, krate, substs, variant, missing_fields);
+        Some(res)
+    }
+
+    pub(crate) fn record_pattern_missing_fields(
+        &self,
+        db: &dyn HirDatabase,
+        pattern: &ast::RecordPat,
+    ) -> Option<Vec<(StructField, Type)>> {
+        let krate = self.resolver.krate()?;
+        let body = self.body.as_ref()?;
+        let infer = self.infer.as_ref()?;
+
+        let pat_id = self.pat_id(&pattern.clone().into())?;
+        let substs = match &infer.type_of_pat[pat_id] {
+            Ty::Apply(a_ty) => &a_ty.parameters,
+            _ => return None,
+        };
+
+        let (variant, missing_fields) =
+            record_pattern_missing_fields(db, infer, pat_id, &body[pat_id])?;
+        let res = self.missing_fields(db, krate, substs, variant, missing_fields);
+        Some(res)
+    }
+
+    fn missing_fields(
+        &self,
+        db: &dyn HirDatabase,
+        krate: CrateId,
+        substs: &Substs,
+        variant: VariantId,
+        missing_fields: Vec<LocalStructFieldId>,
+    ) -> Vec<(StructField, Type)> {
+        let field_types = db.field_types(variant);
+
+        missing_fields
+            .into_iter()
+            .map(|local_id| {
+                let field = StructFieldId { parent: variant, local_id };
+                let ty = field_types[local_id].clone().subst(substs);
+                (field.into(), Type::new_with_resolver_inner(db, krate, &self.resolver, ty))
+            })
+            .collect()
+    }
+
     pub(crate) fn expand(
         &self,
         db: &dyn HirDatabase,