[php-src] Issue #11002: [Zend] Why is GC_FLAGS_SHIFT defined as 0 and twice?

Issue: https://github.com/php/php-src/issues/11002 Author: stkeke ### Description _(look like an issue in source code, but not sure. put it here as it is easier to refer to source code and commits in github)_ I am looking at zend_refcounted.h file and found a group of macro definitions, one of which I hardly make sense - 1) why GC_FLAGS_SHIFT is defined as 0 rather than 4 for access FLAGS bits? 2) macros below are defined twice - one time in zend_types.h and another time in zend_refcounted.h without comments for reason although they have same value? From commit https://github.com/php/php-src/commit/eb34c28fed24d0e4711dd4a04c19d0f95dabc5e9#diff-dca4782c62f10b418ea7193e4641e688ffd7a9c97869f2b1a3a96e28da5653aa, looks like it is trying to split zend_types.h. I tried to comment out macro definitions from zend_types.h and still can make a successful build. https://github.com/php/php-src/blob/master/Zend/zend_types.h#L571 https://github.com/php/php-src/blob/master/Zend/zend_refcounted.h#L26 ```c #define GC_TYPE_MASK 0x0000000f #define GC_FLAGS_MASK 0x000003f0 #define GC_INFO_MASK 0xfffffc00 #define GC_FLAGS_SHIFT 0 #define GC_INFO_SHIFT 10 ``` I know zend_refcount_h has a member type_info, which looks like it has the format of | INFO | FLAGS | TYPE | |-|-|-| |22bits|6bits|4bits| |-|-|-| In function zval_gc_flags, if we only right shift 0 bits, why we need to define this macro? ```c // This function looks weird with GC_FLAGS_SHIFT=0 static zend_always_inline uint32_t zval_gc_flags(uint32_t gc_type_info) { return (gc_type_info >> GC_FLAGS_SHIFT) & (GC_FLAGS_MASK >> GC_FLAGS_SHIFT); } // I can understand this function static zend_always_inline uint8_t zval_gc_type(uint32_t gc_type_info) { return (gc_type_info & GC_TYPE_MASK); } // I can understand this function static zend_always_inline uint32_t zval_gc_info(uint32_t gc_type_info) { return (gc_type_info >> GC_INFO_SHIFT); } ``` ```c typedef struct _zend_refcounted_h { uint32_t refcount; /* reference counter 32-bit */ union { uint32_t type_info; } u; } zend_refcounted_h; ` ### PHP Version PHP 8.3.0-dev ### Operating System All OS