[ci skip] Clarify usage of C99 standard #14993
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This is mostly about mentioning that VLAs which are a required part of C99 conforming implementations (although made optional in the C11 standard) *must* *not* be used in php-src.
devnexen
reviewed
Jul 17, 2024
| counterparts) must be available. | ||
| counterparts) are supposed to be available. | ||
| However, some features (most notably variable-length arrays) which are not | ||
| supported by all relevant compilers, must not be used. |
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Curiosity question: does MSVC still not support VLA ?
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From https://devblogs.microsoft.com/cppblog/c11-and-c17-standard-support-arriving-in-msvc/:
Astute readers will note that VLAs are also not supported. Variable length arrays are generally less efficient than comparable fixed sized arrays, and generally inefficient compared to equivalent malloc(), when safely and securely implemented. VLAs provide attack vectors comparable to those of the infamous gets() — deprecated and destined to removal — for opportunities of “shifting the stack” and other exploits. For these reasons we intend not to support VLAs as an optional feature in C11.
devnexen
approved these changes
Jul 17, 2024
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This is mostly about mentioning that VLAs which are a required part of C99 conforming implementations (although made optional in the C11 standard) must not be used in php-src.
This may help to prevent issues such as #13933.