Merge #1103

1103: Array inference r=flodiebold a=Lapz

Fixes the final item in #394. The only problem is that infering the repeat cause some types to be infered twices.
i.e 
```rust
fn test() {
    let y = unknown;
    [y, &y];
}
```

results in the following diff:

```diff
[11; 48) '{     ...&y]; }': ()
[21; 22) 'y': &{unknown}
[25; 32) 'unknown': &{unknown}
-[38; 45) '[y, &y]': [&&{unknown}]
+[38; 45) '[y, &y]': [&&{unknown};usize]
[39; 40) 'y': &{unknown}
+[39; 40) 'y': &{unknown}
[42; 44) '&y': &&{unknown}
[43; 44) 'y': &{unknown}
```

Should the code produce two inference results for 'y' and if not could any tell me what needs to change.

Co-authored-by: Lenard Pratt <[email protected]>

1 files changed, 17 insertions, 4 deletions

diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index 887153484..9ace6b13a 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -32,7 +32,7 @@ use crate::{
     DefWithBody,
     ImplItem,
     type_ref::{TypeRef, Mutability},
-    expr::{Body, Expr, BindingAnnotation, Literal, ExprId, Pat, PatId, UnaryOp, BinaryOp, Statement, FieldPat, self},
+    expr::{Body, Expr, BindingAnnotation, Literal, ExprId, Pat, PatId, UnaryOp, BinaryOp, Statement, FieldPat,Array, self},
     generics::GenericParams,
     path::{GenericArgs, GenericArg},
     adt::VariantDef,
@@ -1074,7 +1074,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
 
                 Ty::apply(TypeCtor::Tuple, Substs(ty_vec.into()))
             }
-            Expr::Array { exprs } => {
+            Expr::Array(array) => {
                 let elem_ty = match &expected.ty {
                     Ty::Apply(a_ty) => match a_ty.ctor {
                         TypeCtor::Slice | TypeCtor::Array => {
@@ -1085,8 +1085,21 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                     _ => self.new_type_var(),
                 };
 
-                for expr in exprs.iter() {
-                    self.infer_expr(*expr, &Expectation::has_type(elem_ty.clone()));
+                match array {
+                    Array::ElementList(items) => {
+                        for expr in items.iter() {
+                            self.infer_expr(*expr, &Expectation::has_type(elem_ty.clone()));
+                        }
+                    }
+                    Array::Repeat { initializer, repeat } => {
+                        self.infer_expr(*initializer, &Expectation::has_type(elem_ty.clone()));
+                        self.infer_expr(
+                            *repeat,
+                            &Expectation::has_type(Ty::simple(TypeCtor::Int(
+                                primitive::UncertainIntTy::Known(primitive::IntTy::usize()),
+                            ))),
+                        );
+                    }
                 }
 
                 Ty::apply_one(TypeCtor::Array, elem_ty)