On March 29, 2021, arnold@skeeve.com wrote:

The early Go compilers, written in C, were compiled with gcc or clang.

The Plan 9 C compiler was used for the Go runtime's initial
C implementation, but in that context it was only dealing
with the self-contained demands of Go itself, not arbitrary C code
(no standard C library, much of which gawk would need).

Even in that limited context, we spent a frustrating (non-zero)
amount of time stumbling over bugs.
Standard C has moved on, and the Plan 9 C compilers have not kept up.
They're still fine for Plan 9 C code, but given the choice
I wouldn't throw anything else at them.

Best,
Russ