| Issue |
55009
|
| Summary |
clang-tidy false positive va_arg is called on an uninitialized va_list when passing a pointer to va_list
|
| Labels |
|
| Assignees |
|
| Reporter |
Kamilcuk
|
The following MCVE that passes a pointer to `va_list` vauses `clang-tidy` to display an error message that the `va_list` is uninitialized. This is a false positive. `va` is a _pointer_ to `va_list` - it is just getting initialized by the caller.
```
#include <stdarg.h>
int va_list_get_int(va_list *va) {
return va_arg(*va, int);
}
```
when run against `clang-tidy` outputs:
```
$ clang-tidy example.c
Error while trying to load a compilation database:
Could not auto-detect compilation database for file "example.c"
No compilation database found in /dev/shm/.1000.home.tmp.dir or any parent directory
json-compilation-database: Error while opening JSON database: No such file or directory
fixed-compilation-database: Error while opening fixed database: No such file or directory
Running without flags.
1 warning generated.
example.c:3:9: warning: va_arg() is called on an uninitialized va_list [clang-analyzer-valist.Uninitialized]
return va_arg(*va, int);
^
/usr/lib/clang/13.0.1/include/stdarg.h:19:29: note: expanded from macro 'va_arg'
#define va_arg(ap, type) __builtin_va_arg(ap, type)
^~~~~~~~~~~~~~~~~~~~~~~~~~
example.c:3:9: note: va_arg() is called on an uninitialized va_list
return va_arg(*va, int);
^
/usr/lib/clang/13.0.1/include/stdarg.h:19:29: note: expanded from macro 'va_arg'
#define va_arg(ap, type) __builtin_va_arg(ap, type)
^~~~~~~~~~~~~~~~~~~~~~~~~~
```
Environment:
```
$ clang-tidy --version
LLVM (http://llvm.org/):
LLVM version 13.0.1
Optimized build.
Default target: x86_64-pc-linux-gnu
Host CPU: amdfam10
$ clang --version
clang version 13.0.1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
$ uname -a
Linux leonidas 5.17.1-zen1-1-zen #1 ZEN SMP PREEMPT Mon, 28 Mar 2022 21:56:46 +0000 x86_64 GNU/Linux
$ cat /etc/arch-release
Arch Linux release
```
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