GNU89, mixed declarations and loop initial declarations

Question

The default C dialect for GCC and ICC is GNU89. GNU89 allows mixed declarations e.g.

int i;
i = 0;
int j;

I inferred (incorrectly) from a

Answer 1

Mixed declarations and statements predate C89 in other languages (e.g., Algol 68) and was a common extension among a few C89 compilers (not MSCV).

Counter variable declaration in a for statement on the other hand came in C through C++98 and to my knowledge no C89 compiler found it useful enough to add it as a C89 extension.