I'm not sure what the "which will never be fixed" part in the title is about, the problem was clearly fixed in C99 by removing the entire "misfeature" from the standard (e.g. GCC and Clang do error out both in C and C++ compilation mode).
My guess is that the implicit declaration was a leftover from a C predecessor (B?) and kept in C to simplify programming in hybrid B/C environments. Just a guess though.
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I'm not sure what the "which will never be fixed" part in the title is about, the problem was clearly fixed in C99 by removing the entire "misfeature" from the standard (e.g. GCC and Clang do error out both in C and C++ compilation mode).
My guess is that the implicit declaration was a leftover from a C predecessor (B?) and kept in C to simplify programming in hybrid B/C environments. Just a guess though.