From d7a27bf803fd29c499090c7bd0460fae9f0cf0f7 Mon Sep 17 00:00:00 2001
From: danielsan901998 <danielsan901998@gmail.com>
Date: Tue, 30 Jan 2024 16:24:41 +0100
Subject: [PATCH] Use mem.zeroes for empty union initializer list

---
 src/translate_c.zig                           |  5 +++++
 .../empty union initializer list.c            | 20 +++++++++++++++++++
 test/cases/translate_c/static empty struct.c  |  2 +-
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 test/cases/translate_c/empty union initializer list.c

diff --git a/src/translate_c.zig b/src/translate_c.zig
index 6a762468906a..fc2d56ba05da 100644
--- a/src/translate_c.zig
+++ b/src/translate_c.zig
@@ -2505,6 +2505,11 @@ fn transInitListExprRecord(
     var field_inits = std.ArrayList(ast.Payload.ContainerInit.Initializer).init(c.gpa);
     defer field_inits.deinit();
 
+    if (init_count == 0) {
+        const source_loc = @as(*const clang.Expr, @ptrCast(expr)).getBeginLoc();
+        return transZeroInitExpr(c, scope, source_loc, ty);
+    }
+
     var init_i: c_uint = 0;
     var it = record_def.field_begin();
     const end_it = record_def.field_end();
diff --git a/test/cases/translate_c/empty union initializer list.c b/test/cases/translate_c/empty union initializer list.c
new file mode 100644
index 000000000000..33238d2ed8d2
--- /dev/null
+++ b/test/cases/translate_c/empty union initializer list.c	
@@ -0,0 +1,20 @@
+union U {
+    int x;
+    long y;
+};
+
+void foo(void) {
+    union U u = {};
+}
+// translate-c
+// target=x86_64-linux
+// c_frontend=clang
+//
+// pub const union_U = extern union {
+//     x: c_int,
+//     y: c_long,
+// };
+// pub export fn foo() void {
+//     var u: union_U = @import("std").mem.zeroes(union_U);
+//     _ = &u;
+// }
diff --git a/test/cases/translate_c/static empty struct.c b/test/cases/translate_c/static empty struct.c
index 080d7977fdaa..8300b7c673ca 100644
--- a/test/cases/translate_c/static empty struct.c	
+++ b/test/cases/translate_c/static empty struct.c	
@@ -11,7 +11,7 @@ static inline void foo() {
 // pub const struct_empty_struct = extern struct {};
 // pub fn foo() callconv(.C) void {
 //     const bar = struct {
-//         var static: struct_empty_struct = struct_empty_struct{};
+//         var static: struct_empty_struct = @import("std").mem.zeroes(struct_empty_struct);
 //     };
 //     _ = &bar;
 // }