https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82206
--- Comment #1 from Simon Marchi <simon.marchi at polymtl dot ca> ---
Stumbled on this again in the GDB code. Here's another reproducer, probably
the same cause:
---
#include <string>
#include <stdarg.h>
void add_line (const std::string &str);
void string_vappendf (std::string &str, const char *fmt, va_list args)
__attribute__((format(printf, 2, 0)));
void print(const char *fmt, ...)
{
std::string tmp;
va_list ap;
va_start (ap, fmt);
string_vappendf (tmp, fmt, ap);
va_end (ap);
add_line (tmp);
}
---
$ g++-9 test.cpp -c -Wall -Wextra -Wformat-nonliteral
* no warning *
$ clang++-9 test.cpp -c -Wall -Wextra -Wformat-nonliteral
test.cpp:13:25: warning: format string is not a string literal
[-Wformat-nonliteral]
string_vappendf (tmp, fmt, ap);
^~~
1 warning generated.
