| Issue |
120214
|
| Summary |
-Wtautological-compare should flag tautological pointer bounds checks
|
| Labels |
clang:diagnostics
|
| Assignees |
|
| Reporter |
nikic
|
`-Wtautological-compare` should report pointer "bounds checks" patterns that are always true/false because unsigned pointer arithmetic cannot overflow.
```
bool test1(const char *ptr, size_t index) {
return ptr + index < ptr; // always false
}
bool test2(const char *ptr, size_t index) {
return ptr + index >= ptr; // always true
}
```
These two are fine though:
```
bool test3(const char *ptr, ssize_t index) {
return ptr + index < ptr; // unknown
}
bool test4(const char *ptr, ssize_t index) {
return ptr + index >= ptr; // unknown
}
```
Idea from https://github.com/llvm/llvm-project/pull/118472#issuecomment-2548141458.
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