From 25d8faabf6afa80ce86abb23f9c5f4ad6f98159d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=89=A7=E5=BF=83?= <chengqinglin@icloud.com>
Date: Mon, 11 Apr 2022 19:16:09 +0800
Subject: [PATCH] cgen: fix alloc empty struct array error (#14007)

---
 vlib/arrays/arrays_test.v | 12 ++++++++++++
 vlib/v/gen/c/array.v      |  6 ++++--
 vlib/v/gen/c/cheaders.v   |  2 +-
 vlib/v/gen/c/struct.v     | 15 +++++++++++++++
 4 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/vlib/arrays/arrays_test.v b/vlib/arrays/arrays_test.v
index 74eb69b7d3..ee05cfac1f 100644
--- a/vlib/arrays/arrays_test.v
+++ b/vlib/arrays/arrays_test.v
@@ -300,3 +300,15 @@ fn test_alias_string_contains() {
 	names := [Str('')]
 	assert (Str('') in names) == true
 }
+
+struct XYZ {}
+
+fn test_array_append_empty_struct() {
+	mut names := []XYZ{cap: 2}
+	names << XYZ{}
+	assert (XYZ{} in names) == true
+
+	// test fixed array
+	array := [XYZ{}]
+	assert (XYZ{} in names) == true
+}
diff --git a/vlib/v/gen/c/array.v b/vlib/v/gen/c/array.v
index ef32a7e9c4..2941a21943 100644
--- a/vlib/v/gen/c/array.v
+++ b/vlib/v/gen/c/array.v
@@ -151,7 +151,7 @@ fn (mut g Gen) array_init(node ast.ArrayInit) {
 			} else {
 				g.write('0, ')
 			}
-			if elem_type.unaliased_sym.kind == .function {
+			if elem_type.unaliased_sym.kind == .function || g.is_empty_struct(elem_type) {
 				g.write('sizeof(voidptr), ')
 			} else {
 				g.write('sizeof($elem_styp), ')
@@ -217,7 +217,7 @@ fn (mut g Gen) array_init(node ast.ArrayInit) {
 		} else {
 			g.write('0, ')
 		}
-		if elem_type.unaliased_sym.kind == .function {
+		if elem_type.unaliased_sym.kind == .function || g.is_empty_struct(elem_type) {
 			g.write('sizeof(voidptr), ')
 		} else {
 			g.write('sizeof($elem_styp), ')
@@ -251,6 +251,8 @@ fn (mut g Gen) array_init(node ast.ArrayInit) {
 	len := node.exprs.len
 	if elem_type.unaliased_sym.kind == .function {
 		g.write('new_array_from_c_array($len, $len, sizeof(voidptr), _MOV((voidptr[$len]){')
+	} else if g.is_empty_struct(elem_type) {
+		g.write('new_array_from_c_array${noscan}($len, $len, sizeof(voidptr), _MOV(($elem_styp[$len]){')
 	} else {
 		g.write('new_array_from_c_array${noscan}($len, $len, sizeof($elem_styp), _MOV(($elem_styp[$len]){')
 	}
diff --git a/vlib/v/gen/c/cheaders.v b/vlib/v/gen/c/cheaders.v
index c7117e1c1e..f179ce908f 100644
--- a/vlib/v/gen/c/cheaders.v
+++ b/vlib/v/gen/c/cheaders.v
@@ -633,7 +633,7 @@ typedef uint8_t byte;
 typedef uint32_t rune;
 typedef size_t usize;
 typedef ptrdiff_t isize;
-#ifndef VNOFLOAT 
+#ifndef VNOFLOAT
 typedef float f32;
 typedef double f64;
 #else
diff --git a/vlib/v/gen/c/struct.v b/vlib/v/gen/c/struct.v
index fa3600c33d..29fb490bbd 100644
--- a/vlib/v/gen/c/struct.v
+++ b/vlib/v/gen/c/struct.v
@@ -305,3 +305,18 @@ fn (mut g Gen) zero_struct_field(field ast.StructField) bool {
 	}
 	return true
 }
+
+fn (mut g Gen) is_empty_struct(t Type) bool {
+	sym := t.unaliased_sym
+	match sym.info {
+		ast.Struct {
+			if sym.info.fields.len > 0 || sym.info.embeds.len > 0 {
+				return false
+			}
+			return true
+		}
+		else {
+			return false
+		}
+	}
+}