Currently I compile with these flags: alias bd='g++ -std=c++17 -Wshadow -Wall -Wextra -o "a" -g -fsanitize=address -fsanitize=undefined'
Most of the time when I access an out of bounds index I get an error from the sanitizer that tells me the line number, which is good. But sometimes I just get an error that memory is leaked but I get no line number. Are there any flags/compilers which can print the line number consistently when this error occurs, similar to Java's index out of bounds exception?
Use std::vector::at() instead of std::vector::operator []() to get an exception on accessing elements out of range.
.at() dosen't tell me the line number so its worse than what I have now. The flags I have now tell me the line number most of the time (which is pretty good), but not all the time. I guess I just need to code better.
Well, it does not tell you the line number but you can run gdb to find it out.
Add
-D_GLIBCXX_DEBUG(slows your program, but does comprehensive checks) or-D_GLIBCXX_ASSERTIONS(faster, but less error checking) to your compiler flags. These flags check for out of bounds indexing. Then you can run your code in a debugger like gdb, and the debugger will stop the execution of the program when the program aborts on out of bounds indexing.Is this similar to using
-ftrapvflag while compiling?-ftrapvenables checks for arithmetic overflow, while-D_GLIBCXX_DEBUGenables checks for out of bounds indexing, out of bound iterators, and other errors in STL containers. Note that this only works for STL containers, so you'll need to usestd::arrayinstead of a C array.`You can use the __LINE__ C preprocessor macro to write your own bounds-checking function that prints the line number at which the out-of-range error takes place. The following is an example.
Example
If you look at https://github.com/google/sanitizers/wiki/AddressSanitizer, you would get:
To get nicer stack traces in error messages add -fno-omit-frame-pointerWhere can I find the line number?
If you use the D_GLIBCXX_DEBUG flag, then when you use gdb and type "run" and get to the error you can type "where" to see the line number. If you leave out the D_GLIBCXX_DEBUG flag, most of the time you get the line number at runtime from the sanitizers, and when you don't you will get a vague memory leak error, but using gdb you can find the line number just as before. Using the D_GLIBCXX_DEBUG flag, you don't get any line numbers at runtime, but the error description is more precise.
how do we get line no from sanitizers?