Inconsistent C99 support in gcc and clang

Based on this answer, the compiler doesn't have to diagnose the call to such function and verify that the parameters meet the static qualifier.

Note that the C Standard does not require the compiler to diagnose when a call to the function does not meet these requirements (i.e. it is silent undefined behaviour).

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EDIT:

Based on the Standard C99:

6.7.5.3 Function declarators (including prototypes)

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A declaration of a parameter as ‘‘array of type’’ shall be adjusted to ‘‘qualified pointer to type’’, where the type qualifiers (if any) are those specified within the [ and ] of the array type derivation. If the keyword static also appears within the [ and ] of the array type derivation, then for each call to the function, the value of the corresponding actual argument shall provide access to the first element of an array with at least as many elements as specified by the size expression.

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J.2 Undefined behavior

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— A declaration of an array parameter includes the keyword static within the [ and ] and the corresponding argument does not provide access to the first element of an array with at least the specified number of elements (6.7.5.3).