Change zend_ast_attr from uint16_t to uint32_t #20490
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Is this really worthwhile? We can probably shuffle around the flags to make it fit in the 16 bit field if necessary. We also basically just ran out of 32 bit flags anyway, so some shuffling is necessary regardless. |
The zend_ast_attr type was defined as uint16_t, limiting it to 16 bits, but it's used to store ZEND_ACC_* flags which can use bits up to 31: - ZEND_ACC_OVERRIDE = (1 << 28) - ZEND_ACC_ENUM = (1 << 28) - ZEND_ACC_STRICT_TYPES = (1U << 31) While current code doesn't appear to assign these high-bit flags to ast->attr fields, the type mismatch creates a potential bug where any future code attempting to store ZEND_ACC flags with bits 16-31 would have those bits silently truncated to zero. Additionally, several functions (zend_ast_create_va, zend_ast_create_ex_*, etc.) accept uint32_t or zend_ast_attr parameters before assigning to the attr field, creating a truncation point at line 821 in zend_language_parser.y where zend_modifier_list_to_flags() returns uint32_t. This change: 1. Changes zend_ast_kind typedef from uint16_t to uint32_t 2. Changes zend_ast_attr typedef from uint16_t to uint32_t Extending kind to uint32_t maintains natural alignment without requiring explicit padding fields. The structure sizes remain unchanged. Padding was already present implicitly due to alignment.
An alternative would be to change The goal here isn’t to solve the fact that flags are running out, but to make it less surprising for new contributors who wonder why adding a new flag appears to be ignored. |
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The zend_ast_attr type was defined as
uint16_t, limiting it to 16 bits, but it’s used to storeZEND_ACC_*flags which can use bits up to 31:While the current code doesn’t appear to assign these high-bit flags to
ast->attrfields, the type mismatch creates a potential bug where any future code attempting to store ZEND_ACC flags with bits 16–31 would have those bits silently truncated to zero.Additionally, several functions (
zend_ast_create_va,zend_ast_create_ex_*, etc.) acceptuint32_torzend_ast_attrparameters before assigning to the attr field, creating a truncation point at line 821 in zend_language_parser.y wherezend_modifier_list_to_flags()returnsuint32_t.This change:
zend_ast_kindtypedef fromuint16_ttouint32_tzend_ast_attrtypedef fromuint16_ttouint32_tExtending
kindtouint32_tmaintains natural alignment without requiring explicit padding fields. The structure sizes remain unchanged. Padding was already present implicitly due to alignment.