From fd144b30f268bbca57e543b2ac746782b67b37f8 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sat, 18 May 2024 08:35:55 -0300
Subject: [PATCH] cgen: fix C struct init when it has default expr (#21510)

---
 vlib/v/gen/c/cgen.v                           |  7 ++++--
 vlib/v/tests/c_structs/cstruct.h              |  3 ++-
 .../c_structs/cstruct_default_value_test.v    | 25 +++++++++++++++++++
 3 files changed, 32 insertions(+), 3 deletions(-)
 create mode 100644 vlib/v/tests/c_structs/cstruct_default_value_test.v

diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index b5f20e86b6..41f4bf0abf 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -7126,15 +7126,18 @@ fn (mut g Gen) type_default(typ_ ast.Type) string {
 			} else {
 				'{'
 			}
-			if sym.language == .v {
+			if sym.language in [.c, .v] {
 				for field in info.fields {
 					field_sym := g.table.sym(field.typ)
 					if field.has_default_expr
 						|| field_sym.kind in [.array, .map, .string, .bool, .alias, .i8, .i16, .int, .i64, .u8, .u16, .u32, .u64, .f32, .f64, .char, .voidptr, .byteptr, .charptr, .struct_, .chan] {
+						if sym.language == .c && !field.has_default_expr {
+							continue
+						}
 						field_name := c_name(field.name)
 						if field.has_default_expr {
 							mut expr_str := ''
-							if g.table.sym(field.typ).kind in [.sum_type, .interface_] {
+							if field_sym.kind in [.sum_type, .interface_] {
 								expr_str = g.expr_string_with_cast(field.default_expr,
 									field.default_expr_typ, field.typ)
 							} else {
diff --git a/vlib/v/tests/c_structs/cstruct.h b/vlib/v/tests/c_structs/cstruct.h
index 26302f6599..94156494f1 100644
--- a/vlib/v/tests/c_structs/cstruct.h
+++ b/vlib/v/tests/c_structs/cstruct.h
@@ -25,10 +25,11 @@ typedef struct Foo {
 
 typedef struct Bar {
     int a;
+    float b;
 } Bar;
 
 ///
 
 typedef struct TestAlias {
     int a;
-};
\ No newline at end of file
+};
diff --git a/vlib/v/tests/c_structs/cstruct_default_value_test.v b/vlib/v/tests/c_structs/cstruct_default_value_test.v
new file mode 100644
index 0000000000..c67875e992
--- /dev/null
+++ b/vlib/v/tests/c_structs/cstruct_default_value_test.v
@@ -0,0 +1,25 @@
+#include "@VMODROOT/cstruct.h"
+
+struct Foo {
+	a int = 3
+}
+
+struct C.Bar {
+	a int = 3
+	b f64
+}
+
+struct FooBar {
+	foo Foo
+	bar C.Bar
+}
+
+fn test_main() {
+	a := dump(Foo{})
+	b := dump(C.Bar{})
+	c := dump(FooBar{})
+
+	assert a.a == b.a
+	assert b.a == c.bar.a
+	assert b.b == c.bar.b
+}