GCC 12 create a bogus array out of bounds warning as it assumes that
because there is special handling for `uart == 0` and `uart == 1`,
`uart` can indeed be `1`. There is an `assert(uart < UART_NUMOF)` above
that would blow up prior to any out of bounds access.
In any case, optimizing out the special handling of `uart == 1` for
when `UART_NUMOF == 1` likely improves the generated code and fixes
the warning.
/home/maribu/Repos/software/RIOT/cc2650/cpu/cc26xx_cc13xx/periph/uart.c:88:8: error: array subscript 1 is above array bounds of 'uart_isr_ctx_t[1]' [-Werror=array-bounds]
88 | ctx[uart].rx_cb = rx_cb;
| ~~~^~~~~~
/home/maribu/Repos/software/RIOT/cc2650/cpu/cc26xx_cc13xx/periph/uart.c:52:23: note: while referencing 'ctx'
52 | static uart_isr_ctx_t ctx[UART_NUMOF];
| ^~~
/home/maribu/Repos/software/RIOT/cc2650/cpu/cc26xx_cc13xx/periph/uart.c:89:8: error: array subscript 1 is above array bounds of 'uart_isr_ctx_t[1]' [-Werror=array-bounds]
89 | ctx[uart].arg = arg;
| ~~~^~~~~~
/home/maribu/Repos/software/RIOT/cc2650/cpu/cc26xx_cc13xx/periph/uart.c:52:23: note: while referencing 'ctx'
52 | static uart_isr_ctx_t ctx[UART_NUMOF];
| ^~~
