Allow array declaration without size

float c[] = float[](3.14)

src/ast.fs

@@ -33,7 +33,7 @@ type Expr =
   | Float of float * string
   | Var of Ident
   | FunCall of Expr * Expr list
-  | Subscript of Expr * Expr
+  | Subscript of Expr * Expr option
   | Dot of Expr * Ident
   | Cast of Ident * Expr  // hlsl
   | VectorExp of Expr list // hlsl
@@ -107,7 +107,7 @@ let rec mapExpr env = function
   | FunCall(fct, args) ->
      env.fExpr env (FunCall(mapExpr env fct, List.map (mapExpr env) args))
   | Subscript(arr, ind) ->
-     env.fExpr env (Subscript(mapExpr env arr, mapExpr env ind))
+     env.fExpr env (Subscript(mapExpr env arr, Option.map (mapExpr env) ind))
   | Dot(e,  field) -> env.fExpr env (Dot(mapExpr env e, field))
   | Cast(id, e) -> env.fExpr env (Cast(id, mapExpr env e))
   | VectorExp(li) ->

src/parse.fs

@@ -83,7 +83,7 @@ module private ParseImpl =
     let argList = sepBy exprNoComma (ch ',')
     let fcall = between (ch '(') (ch ')') argList |>>
                 (fun args fct -> Ast.FunCall(fct, args))
-    let subscript = between (ch '[') (ch ']') expr |>>
+    let subscript = between (ch '[') (ch ']') (opt expr) |>>
                     (fun ind arr -> Ast.Subscript(arr, ind))
     let dot = ch '.' >>. ident |>> (fun field r -> Ast.Dot(r, field))
     let post = (dot <|> subscript <|> fcall) <?> ""

src/printer.fs

@@ -81,7 +81,7 @@ and exprToSLevel level = function
            else res
         | _ -> out "%s(%s)" (exprToS f) (listToS exprToS "," args)
   | Subscript(arr, ind) ->
-      out "%s[%s]" (exprToS arr) (exprToS ind)
+      out "%s[%s]" (exprToS arr) (defaultArg (Option.map exprToS ind) "")
   | Cast(id, e) ->
       // Cast seems to have the same precedence as unary minus
       out "(%s)%s" id (exprToSLevel precedence.["_-"] e)

tests/unit/array.frag

@@ -4,3 +4,7 @@ float a[3+2] = float[5](3.4, 4.2, 5.0, 5.2, 1.1);
 
 const int size = 5;
 float b[size] = float[size](3.4, 4.2, 5.0, 5.2, 1.1);
+
+float c[] = float[](3.4, 4.2, 5.0, 5.2, 1.1);
+float d[5] = float[](3.4, 4.2, 5.0, 5.2, 1.1);
+float e[] = float[5](3.4, 4.2, 5.0, 5.2, 1.1);