| Issue |
153538
|
| Summary |
std::vector::operator[] allows out-of-bounds assignment on reserved elements in Clang/libc++ while at() correctly throws
|
| Labels |
clang,
libc++
|
| Assignees |
|
| Reporter |
hutuhutong
|
I am not sure whether this behavior needs adjustment. Assigning to a std::vector element via operator[] at an index beyond the current size but within the reserved capacity does not trigger a runtime error in Clang/libc++. In contrast, using v.at() for the same index correctly throws a std::out_of_range exception.
clang20.1.0 -O0 -std=c++20 -stdlib=libc++
========= code ========
#include <vector>
#include <iostream>
int main() {
std::vector<int> v;
v.reserve(10);
// v.at(3) = 42; // will trigger the error
v[3] = 0; // not trigger the error
std::cout << v[3] << "\n";
}
========= output ========
when v.at(3) = 42 is executed, the program output;
ASM generation compiler returned: 0
Execution build compiler returned: 0
Program returned: 139
libc++abi: terminating due to uncaught exception of type std::out_of_range: vector
Program terminated with signal: SIGSEGV
when v[3] = 0 is executed, the program output;
ASM generation compiler returned: 0
Execution build compiler returned: 0
Program returned: 0
0
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