From b596c32a4102643a1c45282092beafb5a31c16a4 Mon Sep 17 00:00:00 2001
From: Jonas Schievink <jonasschievink@gmail.com>
Date: Thu, 22 Jul 2021 13:40:18 +0200
Subject: [PATCH] Resolve tuple variants in value namespace

---
 crates/hir_ty/src/infer.rs          | 29 +++++++++++++++++++++++++----
 crates/hir_ty/src/infer/expr.rs     |  2 +-
 crates/hir_ty/src/infer/pat.rs      |  4 ++--
 crates/hir_ty/src/tests/patterns.rs | 27 +++++++++++++++++++++++++++
 4 files changed, 55 insertions(+), 7 deletions(-)

diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index 154c44afa4..a879ca3823 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -23,7 +23,7 @@ use hir_def::{
     expr::{ArithOp, BinaryOp, BindingAnnotation, ExprId, PatId},
     lang_item::LangItemTarget,
     path::{path, Path},
-    resolver::{HasResolver, Resolver, TypeNs},
+    resolver::{HasResolver, ResolveValueResult, Resolver, TypeNs, ValueNs},
     type_ref::TypeRef,
     AdtId, AssocItemId, DefWithBodyId, EnumVariantId, FieldId, FunctionId, HasModule, Lookup,
     TraitId, TypeAliasId, VariantId,
@@ -548,7 +548,7 @@ impl<'a> InferenceContext<'a> {
         self.table.normalize_associated_types_in(ty)
     }
 
-    fn resolve_variant(&mut self, path: Option<&Path>) -> (Ty, Option<VariantId>) {
+    fn resolve_variant(&mut self, path: Option<&Path>, value_ns: bool) -> (Ty, Option<VariantId>) {
         let path = match path {
             Some(path) => path,
             None => return (self.err_ty(), None),
@@ -557,11 +557,32 @@ impl<'a> InferenceContext<'a> {
         let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver);
         // FIXME: this should resolve assoc items as well, see this example:
         // https://play.rust-lang.org/?gist=087992e9e22495446c01c0d4e2d69521
-        let (resolution, unresolved) =
+        let (resolution, unresolved) = if value_ns {
+            match resolver.resolve_path_in_value_ns(self.db.upcast(), path.mod_path()) {
+                Some(ResolveValueResult::ValueNs(value)) => match value {
+                    ValueNs::EnumVariantId(var) => {
+                        let substs = ctx.substs_from_path(path, var.into(), true);
+                        let ty = self.db.ty(var.parent.into());
+                        let ty = self.insert_type_vars(ty.substitute(&Interner, &substs));
+                        return (ty, Some(var.into()));
+                    }
+                    ValueNs::StructId(strukt) => {
+                        let substs = ctx.substs_from_path(path, strukt.into(), true);
+                        let ty = self.db.ty(strukt.into());
+                        let ty = self.insert_type_vars(ty.substitute(&Interner, &substs));
+                        return (ty, Some(strukt.into()));
+                    }
+                    _ => return (self.err_ty(), None),
+                },
+                Some(ResolveValueResult::Partial(typens, unresolved)) => (typens, Some(unresolved)),
+                None => return (self.err_ty(), None),
+            }
+        } else {
             match resolver.resolve_path_in_type_ns(self.db.upcast(), path.mod_path()) {
                 Some(it) => it,
                 None => return (self.err_ty(), None),
-            };
+            }
+        };
         return match resolution {
             TypeNs::AdtId(AdtId::StructId(strukt)) => {
                 let substs = ctx.substs_from_path(path, strukt.into(), true);
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index f1bc6895c8..d667613428 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -437,7 +437,7 @@ impl<'a> InferenceContext<'a> {
                 TyKind::Never.intern(&Interner)
             }
             Expr::RecordLit { path, fields, spread } => {
-                let (ty, def_id) = self.resolve_variant(path.as_deref());
+                let (ty, def_id) = self.resolve_variant(path.as_deref(), false);
                 if let Some(variant) = def_id {
                     self.write_variant_resolution(tgt_expr.into(), variant);
                 }
diff --git a/crates/hir_ty/src/infer/pat.rs b/crates/hir_ty/src/infer/pat.rs
index 86e2d1b8df..603237f944 100644
--- a/crates/hir_ty/src/infer/pat.rs
+++ b/crates/hir_ty/src/infer/pat.rs
@@ -27,7 +27,7 @@ impl<'a> InferenceContext<'a> {
         id: PatId,
         ellipsis: Option<usize>,
     ) -> Ty {
-        let (ty, def) = self.resolve_variant(path);
+        let (ty, def) = self.resolve_variant(path, true);
         let var_data = def.map(|it| it.variant_data(self.db.upcast()));
         if let Some(variant) = def {
             self.write_variant_resolution(id.into(), variant);
@@ -68,7 +68,7 @@ impl<'a> InferenceContext<'a> {
         default_bm: BindingMode,
         id: PatId,
     ) -> Ty {
-        let (ty, def) = self.resolve_variant(path);
+        let (ty, def) = self.resolve_variant(path, false);
         let var_data = def.map(|it| it.variant_data(self.db.upcast()));
         if let Some(variant) = def {
             self.write_variant_resolution(id.into(), variant);
diff --git a/crates/hir_ty/src/tests/patterns.rs b/crates/hir_ty/src/tests/patterns.rs
index 47aa30d2e3..778d19b747 100644
--- a/crates/hir_ty/src/tests/patterns.rs
+++ b/crates/hir_ty/src/tests/patterns.rs
@@ -889,3 +889,30 @@ fn main() {
         "#]],
     );
 }
+
+#[test]
+fn pattern_lookup_in_value_ns() {
+    check_types(
+        r#"
+use self::Constructor::*;
+struct IntRange {
+    range: (),
+}
+enum Constructor {
+    IntRange(IntRange),
+}
+fn main() {
+    match Constructor::IntRange(IntRange { range: () }) {
+        IntRange(x) => {
+            x;
+          //^ IntRange
+        }
+        Constructor::IntRange(x) => {
+            x;
+          //^ IntRange
+        }
+    }
+}
+    "#,
+    );
+}