[PATCH] lib: utils/serial: Fix compilation errors with LLVM

[Xiang W]

在 2022-11-10星期四的 10:11 +0800，1220749046 at qq.com写道：
> From: zhangleizheng <zhangleizheng at eswincomputing.com>
> 
> Fix: "Getting compilation error on generic firmware #269"
>      opensbi/lib/utils/serial/semihosting.c:158:12: error: result
>      of comparison of constant -1 with expression of type 'char'
>      is always true [-Werror,-Wtautological-constant-out-of-range-compare]
>         ret = ch > -1 ? ch : -1;
> 
> Using clang16 as the compiler.
> 
> Signed-off-by: zhangleizheng <zhangleizheng at eswincomputing.com>

repeat with
https://lists.infradead.org/pipermail/opensbi/2022-November/003543.html
https://lists.infradead.org/pipermail/opensbi/2022-November/003552.html

Regards,
Xiang W

> ---
>  lib/utils/serial/semihosting.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/utils/serial/semihosting.c b/lib/utils/serial/semihosting.c
> index 5012fa1..27dba6f 100644
> --- a/lib/utils/serial/semihosting.c
> +++ b/lib/utils/serial/semihosting.c
> @@ -150,11 +150,11 @@ static void semihosting_putc(char ch)
>  
>  static int semihosting_getc(void)
>  {
> -       char ch = 0;
> +       signed char ch = 0;
>         int ret;
>  
>         if (semihosting_infd < 0)  {
> -               ch = semihosting_trap(SYSREADC, NULL);
> +               ch = (signed char)semihosting_trap(SYSREADC, NULL);
>                 ret = ch > -1 ? ch : -1;
>         } else
>                 ret = semihosting_read(semihosting_infd, &ch, 1) > 0 ? ch : -1;
> -- 
> 2.17.1
> 
>