From 234691b032365e84c4048a809ec5b0cdc4ef0d34 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Thu, 26 Feb 2026 08:38:29 +0300
Subject: [PATCH] parser: fix array init with parenthesized optional elem type
 (fixes #16515)

---
 vlib/v/parser/containers.v                    |  4 +--
 vlib/v/parser/expr.v                          | 25 ++++++++++++++++++-
 ..._init_parenthesized_optional_elem_type.out |  0
 ...y_init_parenthesized_optional_elem_type.vv | 17 +++++++++++++
 4 files changed, 43 insertions(+), 3 deletions(-)
 create mode 100644 vlib/v/parser/tests/array_init_parenthesized_optional_elem_type.out
 create mode 100644 vlib/v/parser/tests/array_init_parenthesized_optional_elem_type.vv

diff --git a/vlib/v/parser/containers.v b/vlib/v/parser/containers.v
index 218f2b4ad..28e1e4b73 100644
--- a/vlib/v/parser/containers.v
+++ b/vlib/v/parser/containers.v
@@ -29,7 +29,7 @@ fn (mut p Parser) array_init(is_option bool, alias_array_type ast.Type) ast.Arra
 			line_nr := p.tok.line_nr
 			p.next()
 			// []string
-			if p.tok.kind in [.name, .amp, .lsbr, .question, .key_shared, .not]
+			if p.tok.kind in [.name, .amp, .lsbr, .lpar, .question, .key_shared, .not]
 				&& p.tok.line_nr == line_nr {
 				elem_type_pos = p.tok.pos()
 				elem_type = p.parse_type()
@@ -77,7 +77,7 @@ fn (mut p Parser) array_init(is_option bool, alias_array_type ast.Type) ast.Arra
 			last_pos = p.tok.pos()
 			p.check(.rsbr)
 			if exprs.len == 1 && p.tok.line_nr == line_nr
-				&& (p.tok.kind in [.name, .amp, .question, .key_shared]
+				&& (p.tok.kind in [.name, .amp, .lpar, .question, .key_shared]
 				|| (p.tok.kind == .lsbr && p.is_array_type())) {
 				// [100]u8
 				elem_type = p.parse_type()
diff --git a/vlib/v/parser/expr.v b/vlib/v/parser/expr.v
index 86845959a..c5fc8288f 100644
--- a/vlib/v/parser/expr.v
+++ b/vlib/v/parser/expr.v
@@ -293,7 +293,30 @@ fn (mut p Parser) check_expr(precedence int) !ast.Expr {
 					prev_n_tok = peek_n_tok
 					peek_n_tok = p.peek_token(n)
 				}
-				if peek_n_tok.kind == .lpar && sbr_level == 0 && peek_n_tok.line_nr == line_nr {
+				mut is_cast_expr := peek_n_tok.kind == .lpar && sbr_level == 0
+					&& peek_n_tok.line_nr == line_nr
+				// `[](?Type){}` (and `[N](?Type){}`) is an array init, not a cast.
+				if is_cast_expr && prev_n_tok.kind == .rsbr {
+					mut par_level := 0
+					for i := n; true; i++ {
+						tk := p.peek_token(i)
+						if tk.kind == .eof {
+							break
+						}
+						if tk.kind == .lpar {
+							par_level++
+						} else if tk.kind == .rpar {
+							par_level--
+							if par_level == 0 {
+								if p.peek_token(i + 1).kind == .lcbr {
+									is_cast_expr = false
+								}
+								break
+							}
+						}
+					}
+				}
+				if is_cast_expr {
 					pos := p.tok.pos()
 					typ := p.parse_type()
 					typname := p.table.sym(typ).name
diff --git a/vlib/v/parser/tests/array_init_parenthesized_optional_elem_type.out b/vlib/v/parser/tests/array_init_parenthesized_optional_elem_type.out
new file mode 100644
index 000000000..e69de29bb
diff --git a/vlib/v/parser/tests/array_init_parenthesized_optional_elem_type.vv b/vlib/v/parser/tests/array_init_parenthesized_optional_elem_type.vv
new file mode 100644
index 000000000..c9b785e2d
--- /dev/null
+++ b/vlib/v/parser/tests/array_init_parenthesized_optional_elem_type.vv
@@ -0,0 +1,17 @@
+struct Struc {}
+
+type StrucOpt = ?Struc
+
+struct StrucContainer {
+	a [](?Struc) = [](?Struc){}
+	b []?Struc   = []?Struc{}
+	c ?[]Struc
+}
+
+fn main() {
+	a := [](?Struc){}
+	b := []?Struc{}
+	c := []StrucOpt{}
+	d := [](?Struc)(b)
+	println(a.len + b.len + c.len + d.len)
+}
-- 
2.39.5