[clang] [clang][CGRecordLayout] Remove dependency on isZeroSize (PR #96422)

[Michael Buch via cfe-commits]

================
@@ -1,7 +1,17 @@
-// RUN: %clang_cc1 -emit-llvm < %s | grep "zeroinitializer, i16 16877"
+// RUN: %clang_cc1 %s -emit-llvm -o - | FileCheck %s
 // PR4390
 struct sysfs_dirent {
- union { struct sysfs_elem_dir {} s_dir; };
+ union { struct sysfs_elem_dir { int x; } s_dir; };
  unsigned short s_mode;
 };
 struct sysfs_dirent sysfs_root = { {}, 16877 };
+
+// CHECK: @sysfs_root = global %struct.sysfs_dirent { %union.anon zeroinitializer, i16 16877 }
+
+struct Foo {
+ union { struct empty {} x; };
+ unsigned short s_mode;
----------------
Michael137 wrote:

Yup, can confirm that as C++ we'd get:
```
%struct.sysfs_dirent = type { [2 x i8], i16 }                                    
                                                                                 
@sysfs_root = global %struct.sysfs_dirent { [2 x i8] undef, i16 16877 }, align 2 
```

https://github.com/llvm/llvm-project/pull/96422