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Jul 18, 2024
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[ci skip] Clarify usage of C99 standard #14993

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7 changes: 5 additions & 2 deletions CODING_STANDARDS.md
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Expand Up @@ -9,9 +9,12 @@ rewritten to comply with these rules.

1. Document your code in source files and the manual. (tm)

1. PHP is implemented in C99. The optional fixed-width integers from
1. PHP is implemented in C99.
For instance, the optional fixed-width integers from
stdint.h (int8_t, int16_t, int32_t, int64_t and their unsigned
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.


1. Functions that are given pointers to resources should not free them.

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