c - FlexeLint 在 va_list 上抛出错误

Question

为什么 FLexeLint 在下面的代码中抛出错误“警告 530:符号‘va’(第 23 行)未初始化”。

void debug(int msglevel, const char *fmt, ...)
{
va_list va;
va_start(va, fmt);
vfprintf(stderr, fmt, va);
va_end(va);
}

是否需要初始化va_list？

Answer 1

没有必要。来自man page for stdarg :

void va_start(va_list ap, last);

The va_start() macro initializes ap for subsequent use by va_arg() and va_end(), and must be called first.

此外，来自 C standard 的第 7.16.1.4 节:

2 The va_start macro shall be invoked before any access to the unnamed arguments.

3 The va_start macro initializes ap for subsequent use by the va_arg and va_end macros. Neither the va_start nor va_copy macro shall be invoked to reinitialize ap without an intervening invocation of the va_end macro for the same ap .