parser: support casting to a pointer to array (#7861)

vlib/v/fmt/fmt.v

@@ -831,10 +831,9 @@ pub fn (mut f Fmt) enum_decl(node ast.EnumDecl) {
 
 pub fn (mut f Fmt) prefix_expr_cast_expr(fexpr ast.Expr) {
 	mut is_pe_amp_ce := false
-	mut ce := ast.CastExpr{}
 	if fexpr is ast.PrefixExpr {
 		if fexpr.right is ast.CastExpr && fexpr.op == .amp {
-			ce = fexpr.right as ast.CastExpr
+			mut ce := fexpr.right as ast.CastExpr
 			ce.typname = f.table.get_type_symbol(ce.typ).name
 			is_pe_amp_ce = true
 			f.expr(ce)

vlib/v/fmt/tests/type_ptr_keep.vv

@@ -1,19 +1,15 @@
 const (
 	x  = &Test{}
 	y  = []&Test{}
-	z  = &[]&Test{}
 	xx = &&Test{}
 	yy = []&&Test{}
-	zz = &&[]&&Test{}
 )
 
 fn test_type_ptr() {
 	_ := &Test{}
 	_ := []&Test{}
-	_ := &[]&Test{}
 	_ := &&Test{}
 	_ := []&&Test{}
-	_ := &&[]&&Test{}
 }
 
 struct Test {

vlib/v/parser/pratt.v

@@ -127,6 +127,17 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 			if p.expecting_type {
 				// parse json.decode type (`json.decode([]User, s)`)
 				node = p.name_expr()
+			} else if p.is_amp && p.peek_tok.kind == .rsbr {
+				pos := p.tok.position()
+				typ := p.parse_type().to_ptr()
+				p.check(.lpar)
+				expr := p.expr(0)
+				p.check(.rpar)
+				node = ast.CastExpr{
+					typ: typ
+					expr: expr
+					pos: pos
+				}
 			} else {
 				node = p.array_init()
 			}

vlib/v/tests/array_cast_test.v

@@ -0,0 +1,19 @@
+fn test_array_cast() {
+	mut keys := ['']
+	unsafe {
+		vp := voidptr(&keys)
+		mut p := &[]string(vp)
+		(*p)[0] = 'hi'
+		assert *p == ['hi']
+	}
+	assert keys[0] == 'hi'
+}
+
+fn test_int() {
+	mut arr := [2.3,3]
+	unsafe {
+		vp := voidptr(&arr)
+		p := &[]f64(vp)
+		assert *p == arr
+	}
+}