cgen: fix error caused by fixed size array init syntax with variable it (#12314)

vlib/v/gen/c/array.v

@@ -23,6 +23,61 @@ fn (mut g Gen) array_init(node ast.ArrayInit) {
 		g.write('HEAP($array_styp, ')
 	}
 	if array_type.unaliased_sym.kind == .array_fixed {
+		if node.has_it {
+			g.inside_lambda = true
+			tmp := g.new_tmp_var()
+			mut s := g.go_before_stmt(0)
+			s_ends_with_ln := s.ends_with('\n')
+			s = s.trim_space()
+			ret_typ := g.typ(node.typ)
+			elem_typ := g.typ(node.elem_type)
+			g.empty_line = true
+			g.write('$ret_typ $tmp =')
+			g.write('{')
+			if node.has_val {
+				for i, expr in node.exprs {
+					if expr.is_auto_deref_var() {
+						g.write('*')
+					}
+					g.write('0')
+					if i != node.exprs.len - 1 {
+						g.write(', ')
+					}
+				}
+			} else if node.has_default {
+				g.write('0')
+				info := array_type.unaliased_sym.info as ast.ArrayFixed
+				for _ in 1 .. info.size {
+					g.write(', ')
+					g.write('0')
+				}
+			} else {
+				g.write('0')
+			}
+			g.write('}')
+			g.writeln(';')
+			g.writeln('{')
+			g.indent++
+			g.writeln('$elem_typ* pelem = ($elem_typ*)$tmp;')
+			g.writeln('int _len = (int)sizeof($tmp) / sizeof($elem_typ);')
+			g.writeln('for(int it=0; it<_len; it++, pelem++) {')
+			g.indent++
+			g.write('*pelem = ')
+			g.expr(node.default_expr)
+			g.writeln(';')
+			g.indent--
+			g.writeln('}')
+			g.indent--
+			g.writeln('}')
+			if s_ends_with_ln {
+				g.writeln(s)
+			} else {
+				g.write(s)
+			}
+			g.write(tmp)
+			g.inside_lambda = false
+			return
+		}
 		g.write('{')
 		if node.has_val {
 			for i, expr in node.exprs {

vlib/v/gen/c/cgen.v

@@ -3197,18 +3197,7 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 				} else if is_decl {
 					if is_fixed_array_init && !has_val {
 						if val is ast.ArrayInit {
-							if val.has_default {
-								g.write('{')
-								g.expr(val.default_expr)
-								info := right_sym.info as ast.ArrayFixed
-								for _ in 1 .. info.size {
-									g.write(', ')
-									g.expr(val.default_expr)
-								}
-								g.write('}')
-							} else {
-								g.write('{0}')
-							}
+							g.array_init(val)
 						} else {
 							g.write('{0}')
 						}

vlib/v/gen/c/infix_expr.v

@@ -163,15 +163,19 @@ fn (mut g Gen) infix_expr_eq_op(node ast.InfixExpr) {
 					g.write('*')
 				}
 				if node.left is ast.ArrayInit {
+					if !node.left.has_it {
 						s := g.typ(left.unaliased)
 						g.write('($s)')
 					}
+				}
 				g.expr(node.left)
 				g.write(', ')
 				if node.right is ast.ArrayInit {
+					if !node.right.has_it {
 						s := g.typ(right.unaliased)
 						g.write('($s)')
 					}
+				}
 				g.expr(node.right)
 				g.write(')')
 			}

vlib/v/gen/c/str.v

@@ -119,9 +119,11 @@ fn (mut g Gen) gen_expr_to_string(expr ast.Expr, etype ast.Type) {
 		if expr is ast.ArrayInit {
 			if expr.is_fixed {
 				s := g.typ(expr.typ)
+				if !expr.has_it {
 					g.write('($s)')
 				}
 			}
+		}
 		g.expr_with_cast(expr, typ, typ)
 		if is_shared {
 			g.write('->val')

vlib/v/tests/array_with_it_test.v

@@ -1,4 +1,5 @@
 fn test_array_with_it() {
+	assert [0, 1, 2, 3, 4, 5]! == [6]int{init: it}
 	assert [0, 1, 4, 9, 16, 25] == []int{len: 6, init: it * it}
 	assert [1, 2, 3, 4, 5] == []int{len: 5, init: it + 1}
 	assert [5, 4, 3, 2, 1] == []int{len: 5, init: 5 - it}