Merge #1290

1290: Add Union to code_model r=matklad a=matklad

@flodiebold I am conflicted about two possible implementation approaches:

* we can add a separate `struct Union` to code model
* we can add `fn is_union(&self)` to existing `Struct`

This PR goes with the former approach, because it seems like Unions are sufficiently different in semantics to warrant a separate types. Which is in contrast to Syntax Tree, where both structs and unions share the same node kind, because their syntax is the same. 

What would be the right thing to do here?

Co-authored-by: Aleksey Kladov <[email protected]>

1 files changed, 13 insertions, 8 deletions

diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index a48272981..7d8250292 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -27,13 +27,13 @@ use ra_prof::profile;
 use test_utils::tested_by;
 
 use crate::{
-    Function, StructField, Path, Name,
-    FnSignature, AdtDef,ConstSignature,
-    HirDatabase,
-    DefWithBody,
-    ImplItem,
+    Function, StructField, Path, Name, FnSignature, AdtDef, ConstSignature, HirDatabase,
+    DefWithBody, ImplItem,
     type_ref::{TypeRef, Mutability},
-    expr::{Body, Expr, BindingAnnotation, Literal, ExprId, Pat, PatId, UnaryOp, BinaryOp, Statement, FieldPat,Array, self},
+    expr::{
+        Body, Expr, BindingAnnotation, Literal, ExprId, Pat, PatId, UnaryOp, BinaryOp, Statement,
+        FieldPat, Array, self,
+    },
     generics::{GenericParams, HasGenericParams},
     path::{GenericArgs, GenericArg},
     ModuleDef,
@@ -644,7 +644,8 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 let ty = self.insert_type_vars(ty.apply_substs(substs));
                 (ty, Some(var.into()))
             }
-            TypableDef::TypeAlias(_)
+            TypableDef::Union(_)
+            | TypableDef::TypeAlias(_)
             | TypableDef::Function(_)
             | TypableDef::Enum(_)
             | TypableDef::Const(_)
@@ -1407,7 +1408,11 @@ impl Expectation {
 }
 
 mod diagnostics {
-    use crate::{expr::ExprId, diagnostics::{DiagnosticSink, NoSuchField}, HirDatabase, Function};
+    use crate::{
+        expr::ExprId,
+        diagnostics::{DiagnosticSink, NoSuchField},
+        HirDatabase, Function,
+};
 
     #[derive(Debug, PartialEq, Eq, Clone)]
     pub(super) enum InferenceDiagnostic {