__curl_rule_01__ declared as an array with a negative size

Question

I added arm64 support in the build settings of my app now get this error in the curlrules.h, Here is the code where the error occurs:

typedef char
 __curl_rule_01__
 [CurlchkszEQ(long, CURL_SIZEOF_LONG)]; //where the error occurs

Answer 1

Well, obviously you need to make sure that CURL_SIZEOF_LONG is defined as sizeof(long) (or the integer-literal equivalent, probably 8) wherever it's defined. You're probably trying to #include a header that still thinks you're on 32-bit ARM.

The "array with negative size" trick is a very common trick to simulate static_assert in C and in C++-pre-2011. Look in the source code for the definition of CurlchkszEQ if you want to know how it works in this particular case.