lib/vsprintf: Replace hidden BUILD_BUG_ON() with static_assert()

First of all, there is no compile time check for the SMALL
to be ' ' (0x20, i.e. space). Second, for ZEROPAD the check
is hidden in the code.

For better maintenance replace BUILD_BUG_ON() with static_assert()
for ZEROPAD and move it closer to the definition. While at it,
introduce check for SMALL.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Link: https://lore.kernel.org/r/20200731180825.30575-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 31a674dd2674c56a48e9b96e6f04e42ad4d6777a..f90f096829774ee580f0db45b9b71e77ed697a6e 100644 (file)
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -381,6 +381,9 @@ int num_to_str(char *buf, int size, unsigned long long num, unsigned int width)
 #define SMALL  32              /* use lowercase in hex (must be 32 == 0x20) */
 #define SPECIAL        64              /* prefix hex with "0x", octal with "0" */
 
+static_assert(ZEROPAD == ('0' - ' '));
+static_assert(SMALL == ' ');
+
 enum format_type {
        FORMAT_TYPE_NONE, /* Just a string part */
        FORMAT_TYPE_WIDTH,
@@ -507,7 +510,7 @@ char *number(char *buf, char *end, unsigned long long num,
        /* zero or space padding */
        if (!(spec.flags & LEFT)) {
                char c = ' ' + (spec.flags & ZEROPAD);
-               BUILD_BUG_ON(' ' + ZEROPAD != '0');
+
                while (--field_width >= 0) {
                        if (buf < end)
                                *buf = c;