Added ArrayExprKind,

changed the  display for fixed array types,
Added Array Enum to ra_hir/expr

crates/ra_hir/src/expr.rs

@@ -6,7 +6,7 @@ use rustc_hash::FxHashMap;
 use ra_arena::{Arena, RawId, impl_arena_id, map::ArenaMap};
 use ra_syntax::{
     SyntaxNodePtr, AstPtr, AstNode,
-    ast::{self, LoopBodyOwner, ArgListOwner, NameOwner, LiteralKind, TypeAscriptionOwner}
+    ast::{self, LoopBodyOwner, ArgListOwner, NameOwner, LiteralKind,ArrayExprKind, TypeAscriptionOwner}
 };
 
 use crate::{
@@ -238,15 +238,17 @@ pub enum Expr {
     Tuple {
         exprs: Vec<ExprId>,
     },
-    Array {
-        exprs: Vec<ExprId>,
-        repeat: Option<ExprId>,
-    },
+    Array(Array),
     Literal(Literal),
 }
 
 pub use ra_syntax::ast::PrefixOp as UnaryOp;
 pub use ra_syntax::ast::BinOp as BinaryOp;
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub enum Array {
+    ElementList(Vec<ExprId>),
+    Repeat { initializer: ExprId, repeat: ExprId },
+}
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub struct MatchArm {
@@ -354,15 +356,17 @@ impl Expr {
                     f(*expr);
                 }
             }
-            Expr::Array { exprs, repeat } => {
-                for expr in exprs {
-                    f(*expr);
+            Expr::Array(a) => match a {
+                Array::ElementList(exprs) => {
+                    for expr in exprs {
+                        f(*expr);
+                    }
                 }
-
-                if let Some(expr) = repeat {
-                    f(*expr)
+                Array::Repeat { initializer, repeat } => {
+                    f(*initializer);
+                    f(*repeat)
                 }
-            }
+            },
             Expr::Literal(_) => {}
         }
     }
@@ -733,11 +737,26 @@ impl ExprCollector {
                 let exprs = e.exprs().map(|expr| self.collect_expr(expr)).collect();
                 self.alloc_expr(Expr::Tuple { exprs }, syntax_ptr)
             }
+
             ast::ExprKind::ArrayExpr(e) => {
-                let exprs = e.exprs().map(|expr| self.collect_expr(expr)).collect();
-                let repeat = e.repeat().map(|e| self.collect_expr(e));
-                self.alloc_expr(Expr::Array { exprs, repeat }, syntax_ptr)
+                let kind = e.kind();
+
+                match kind {
+                    ArrayExprKind::ElementList(e) => {
+                        let exprs = e.map(|expr| self.collect_expr(expr)).collect();
+                        self.alloc_expr(Expr::Array(Array::ElementList(exprs)), syntax_ptr)
+                    }
+                    ArrayExprKind::Repeat { initializer, repeat } => {
+                        let initializer = self.collect_expr_opt(initializer);
+                        let repeat = self.collect_expr_opt(repeat);
+                        self.alloc_expr(
+                            Expr::Array(Array::Repeat { initializer, repeat }),
+                            syntax_ptr,
+                        )
+                    }
+                }
             }
+
             ast::ExprKind::Literal(e) => {
                 let lit = match e.kind() {
                     LiteralKind::IntNumber { suffix } => {

crates/ra_hir/src/ty.rs

@@ -359,7 +359,7 @@ impl HirDisplay for ApplicationTy {
             }
             TypeCtor::Array => {
                 let t = self.parameters.as_single();
-                write!(f, "[{};usize]", t.display(f.db))?;
+                write!(f, "[{};_]", t.display(f.db))?;
             }
             TypeCtor::RawPtr(m) => {
                 let t = self.parameters.as_single();

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, repeat } => {
+            Expr::Array(array) => {
                 let elem_ty = match &expected.ty {
                     Ty::Apply(a_ty) => match a_ty.ctor {
                         TypeCtor::Slice | TypeCtor::Array => {
@@ -1085,17 +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()));
-                }
-
-                if let Some(expr) = repeat {
-                    self.infer_expr(
-                        *expr,
-                        &Expectation::has_type(Ty::simple(TypeCtor::Int(
-                            primitive::UncertainIntTy::Known(primitive::IntTy::usize()),
-                        ))),
-                    );
+                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)

crates/ra_syntax/src/ast.rs

@@ -17,8 +17,8 @@ pub use self::{
     generated::*,
     traits::*,
     tokens::*,
-    extensions::{PathSegmentKind, StructKind, FieldKind, SelfParamKind},
-    expr_extensions::{ElseBranch, PrefixOp, BinOp, LiteralKind},
+    extensions::{PathSegmentKind, StructKind, SelfParamKind},
+    expr_extensions::{ElseBranch, PrefixOp, BinOp, LiteralKind,ArrayExprKind},
 };
 
 /// The main trait to go from untyped `SyntaxNode`  to a typed ast. The

crates/ra_syntax/src/ast/expr_extensions.rs

@@ -193,6 +193,28 @@ impl ast::BinExpr {
     }
 }
 
+pub enum ArrayExprKind<'a> {
+    Repeat { initializer: Option<&'a ast::Expr>, repeat: Option<&'a ast::Expr> },
+    ElementList(AstChildren<'a, ast::Expr>),
+}
+
+impl ast::ArrayExpr {
+    pub fn kind(&self) -> ArrayExprKind {
+        if self.is_repeat() {
+            ArrayExprKind::Repeat {
+                initializer: children(self).nth(0),
+                repeat: children(self).nth(2),
+            }
+        } else {
+            ArrayExprKind::ElementList(children(self))
+        }
+    }
+
+    fn is_repeat(&self) -> bool {
+        self.syntax().children_with_tokens().any(|it| it.kind() == SEMI)
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub enum LiteralKind {
     String,