Commit 675590cd44

@@ -8962,7 +8962,7 @@ static void resolve_llvm_types_struct(CodeGen *g, ZigType *struct_type, ResolveS
         struct_type->data.structure.llvm_full_type_queue_index = SIZE_MAX;
     }
 
-    if (struct_type->abi_size <= 16 && struct_type->data.structure.layout == ContainerLayoutExtern)
+    if (struct_type->abi_size <= 16 && (struct_type->data.structure.layout == ContainerLayoutExtern || struct_type->data.structure.layout == ContainerLayoutPacked))
         resolve_llvm_c_abi_type(g, struct_type);
 }
 

@@ -75,6 +75,24 @@ struct MedStructMixed {
 void zig_med_struct_mixed(struct MedStructMixed);
 struct MedStructMixed zig_ret_med_struct_mixed();
 
+struct SmallPackedStruct {
+    uint8_t a: 2;
+    uint8_t b: 2;
+    uint8_t c: 2;
+    uint8_t d: 2;
+    uint8_t e: 1;
+};
+
+struct BigPackedStruct {
+    uint64_t a: 64;
+    uint64_t b: 64;
+    uint64_t c: 64;
+    uint64_t d: 64;
+    uint8_t e: 8;
+};
+
+//void zig_small_packed_struct(struct SmallPackedStruct); // #1481
+void zig_big_packed_struct(struct BigPackedStruct);
 
 struct SplitStructInts {
     uint64_t a;
@@ -137,6 +155,16 @@ void run_c_tests(void) {
         zig_small_struct_ints(s);
     }
 
+    {
+        struct BigPackedStruct s = {1, 2, 3, 4, 5};
+        zig_big_packed_struct(s);
+    }
+
+    {
+        struct SmallPackedStruct s = {0, 1, 2, 3, 1};
+        //zig_small_packed_struct(s);
+    }
+
     {
         struct SplitStructInts s = {1234, 100, 1337};
         zig_split_struct_ints(s);
@@ -318,6 +346,44 @@ void c_split_struct_mixed(struct SplitStructMixed x) {
     assert_or_panic(y.c == 1337.0f);
 }
 
+struct SmallPackedStruct c_ret_small_packed_struct() {
+    struct SmallPackedStruct s = {
+        .a = 0,
+        .b = 1,
+        .c = 2,
+        .d = 3,
+        .e = 1,
+    };
+    return s;
+}
+
+void c_small_packed_struct(struct SmallPackedStruct x) {
+    assert_or_panic(x.a == 0);
+    assert_or_panic(x.a == 1);
+    assert_or_panic(x.a == 2);
+    assert_or_panic(x.a == 3);
+    assert_or_panic(x.e == 1);
+}
+
+struct BigPackedStruct c_ret_big_packed_struct() {
+    struct BigPackedStruct s = {
+        .a = 1,
+        .b = 2,
+        .c = 3,
+        .d = 4,
+        .e = 5,
+    };
+    return s;
+}
+
+void c_big_packed_struct(struct BigPackedStruct x) {
+    assert_or_panic(x.a == 1);
+    assert_or_panic(x.b == 2);
+    assert_or_panic(x.c == 3);
+    assert_or_panic(x.d == 4);
+    assert_or_panic(x.e == 5);
+}
+
 struct SplitStructMixed c_ret_split_struct_mixed() {
     struct SplitStructMixed s = {
         .a = 1234,

@@ -230,6 +230,65 @@ export fn zig_small_struct_ints(x: SmallStructInts) void {
     expect(x.d == 4) catch @panic("test failure");
 }
 
+const SmallPackedStruct = packed struct {
+    a: u2,
+    b: u2,
+    c: u2,
+    d: u2,
+    e: bool,
+};
+const c_small_packed_struct: fn (SmallPackedStruct) callconv(.C) void = @compileError("TODO: #1481");
+extern fn c_ret_small_packed_struct() SmallPackedStruct;
+
+// waiting on #1481
+//export fn zig_small_packed_struct(x: SmallPackedStruct) void {
+//    expect(x.a == 0) catch @panic("test failure");
+//    expect(x.b == 1) catch @panic("test failure");
+//    expect(x.c == 2) catch @panic("test failure");
+//    expect(x.d == 3) catch @panic("test failure");
+//    expect(x.e) catch @panic("test failure");
+//}
+
+test "C ABI small packed struct" {
+    var s = SmallPackedStruct{ .a = 0, .b = 1, .c = 2, .d = 3, .e = true };
+    _ = s; //c_small_packed_struct(s); // waiting on #1481
+    var s2 = c_ret_small_packed_struct();
+    try expect(s2.a == 0);
+    try expect(s2.b == 1);
+    try expect(s2.c == 2);
+    try expect(s2.d == 3);
+    try expect(s2.e);
+}
+
+const BigPackedStruct = packed struct {
+    a: u64,
+    b: u64,
+    c: u64,
+    d: u64,
+    e: u8,
+};
+extern fn c_big_packed_struct(BigPackedStruct) void;
+extern fn c_ret_big_packed_struct() BigPackedStruct;
+
+export fn zig_big_packed_struct(x: BigPackedStruct) void {
+    expect(x.a == 1) catch @panic("test failure");
+    expect(x.b == 2) catch @panic("test failure");
+    expect(x.c == 3) catch @panic("test failure");
+    expect(x.d == 4) catch @panic("test failure");
+    expect(x.e == 5) catch @panic("test failure");
+}
+
+test "C ABI big packed struct" {
+    var s = BigPackedStruct{ .a = 1, .b = 2, .c = 3, .d = 4, .e = 5 };
+    c_big_packed_struct(s);
+    var s2 = c_ret_big_packed_struct();
+    try expect(s2.a == 1);
+    try expect(s2.b == 2);
+    try expect(s2.c == 3);
+    try expect(s2.d == 4);
+    try expect(s2.e == 5);
+}
+
 const SplitStructInt = extern struct {
     a: u64,
     b: u8,