`-Wuninitialized-const-pointer` fires on valid MemorySanitizer usage
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clang:diagnostics
compiler-rt:msan
- Dominant language
- LLVM
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Description
The recently introduced -Wuninitialized-const-pointer warning is triggered by a legitimate usage of the MemorySanitizer __msan_allocated_memory call:
#include <sanitizer/msan_interface.h>
int main(void) {
int a;
__msan_allocated_memory(&a, sizeof(a));
return 0;
}
Command and output:
$ clang-21 test.c -o test -fsanitize=memory -Wall
test.c:4:28: warning: variable 'a' is uninitialized when passed as a const pointer argument here [-Wuninitialized-const-pointer]
4 | __msan_allocated_memory(&a, sizeof(a));
| ^
1 warning generated.
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Research direction
Reproduce the report with the C example, the sanitizer/msan_interface.h declaration, and the shown clang-21 command using -fsanitize=memory -Wall. Trace how -Wuninitialized-const-pointer handles the __msan_allocated_memory call; done means this valid MemorySanitizer usage no longer emits the warning while the warning still diagnoses genuine cases.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- c
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100