stage2: Implement explicit backing integers for packed structs

Now the backing integer of a packed struct type may be explicitly
specified with e.g. `packed struct(u32) { ... }`.

1 files changed, 55 insertions, 0 deletions

diff --git a/test/cases/compile_errors/packed_struct_backing_int_wrong.zig b/test/cases/compile_errors/packed_struct_backing_int_wrong.zig
new file mode 100644
index 0000000000..cd1b4ec11c
--- /dev/null
+++ b/test/cases/compile_errors/packed_struct_backing_int_wrong.zig
@@ -0,0 +1,55 @@
+export fn entry1() void {
+    _ = @sizeOf(packed struct(u32) {
+        x: u1,
+        y: u24,
+        z: u4,
+    });
+}
+export fn entry2() void {
+    _ = @sizeOf(packed struct(i31) {
+        x: u4,
+        y: u24,
+        z: u4,
+    });
+}
+
+export fn entry3() void {
+    _ = @sizeOf(packed struct(void) {
+        x: void,
+    });
+}
+
+export fn entry4() void {
+    _ = @sizeOf(packed struct(void) {});
+}
+
+export fn entry5() void {
+    _ = @sizeOf(packed struct(noreturn) {});
+}
+
+export fn entry6() void {
+    _ = @sizeOf(packed struct(f64) {
+        x: u32,
+        y: f32,
+    });
+}
+
+export fn entry7() void {
+    _ = @sizeOf(packed struct(*u32) {
+        x: u4,
+        y: u24,
+        z: u4,
+    });
+}
+
+// error
+// backend=llvm
+// target=native
+//
+// :2:31: error: backing integer type 'u32' has bit size 32 but the struct fields have a total bit size of 29
+// :9:31: error: backing integer type 'i31' has bit size 31 but the struct fields have a total bit size of 32
+// :17:31: error: expected backing integer type, found 'void'
+// :23:31: error: expected backing integer type, found 'void'
+// :27:31: error: expected backing integer type, found 'noreturn'
+// :31:31: error: expected backing integer type, found 'f64'
+// :38:31: error: expected backing integer type, found '*u32'