Issue #12657 has been updated by Nobuyoshi Nakada.

Description updated
Status changed from Open to Feedback

Does this patch really compile?
`cls` in `RBASIC_CLEAR_CLASS` sometimes isn't an l-value, and should not be able to be the operand of unary '&'.

----------------------------------------
Bug #12657: [PATCH] ANSI aliasing fix for XL compiler
https://bugs.ruby-lang.org/issues/12657#change-59981

* Author: Zarko  Todorovski
* Status: Feedback
* Priority: Normal
* Assignee: 
* ruby -v: 2.3.1
* Backport: 2.1: UNKNOWN, 2.2: UNKNOWN, 2.3: UNKNOWN
----------------------------------------
This is related to Bug #12191.

Changing in internal.h:983-985

from :

```diff
-#define RBASIC_CLEAR_CLASS(obj)        (((struct RBasicRaw *)((VALUE)(obj)))->klass = 0)
-#define RBASIC_SET_CLASS_RAW(obj, cls) (((struct RBasicRaw *)((VALUE)(obj)))->klass = (cls))
```

to:

```C
#ifdef __ibmxl__
    #define RBASIC_SET_CLASS_RAW(obj, cls) memcpy(&((struct RBasicRaw *)((VALUE)(obj)))->klass, &(cls), sizeof(VALUE))
#else
    #define RBASIC_SET_CLASS_RAW(obj, cls) (((struct RBasicRaw *)((VALUE)(obj)))->klass = (cls))
#endif

#ifdef __ibmxl__
    #define RBASIC_CLEAR_CLASS(obj)        memset(&(((struct RBasicRaw *)((VALUE)(obj)))->klass), 0, sizeof(((struct RBasicRaw *)((VALUE)(obj)))->klass))
#else
    #define RBASIC_CLEAR_CLASS(obj)        (((struct RBasicRaw *)((VALUE)(obj)))->klass = 0)
#endif
```

This allows for ruby to build using XL compiler. Otherwise build fails because of ANSI aliasing issues. 

---Files--------------------------------
RBASIC_aliasing.patch (1.04 KB)


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