# Clang 4 documentation

## LeakSanitizer

- Introduction
- Usage
- More Information

## Introduction

LeakSanitizer is a run-time memory leak detector. It can be combined with AddressSanitizer to get both memory error and leak detection, or used in a stand-alone mode. LSan adds almost no performance overhead until the very end of the process, at which point there is an extra leak detection phase.

## Usage

LeakSanitizer is only supported on x86_64 Linux. In order to use it, simply build your program with AddressSanitizer:

    $ cat memory-leak.c
    #include <stdlib.h>
    void *p;
    int main() {
      p = malloc(7);
      p = 0; // The memory is leaked here.
      return 0;
    }
    % clang -fsanitize=address -g memory-leak.c ; ./a.out
    ==23646==ERROR: LeakSanitizer: detected memory leaks
    Direct leak of 7 byte(s) in 1 object(s) allocated from:
        #0 0x4af01b in __interceptor_malloc /projects/compiler-rt/lib/asan/asan_malloc_linux.cc:52:3
        #1 0x4da26a in main memory-leak.c:4:7
        #2 0x7f076fd9cec4 in __libc_start_main libc-start.c:287
    SUMMARY: AddressSanitizer: 7 byte(s) leaked in 1 allocation(s).

To use LeakSanitizer in stand-alone mode, link your program with `-fsanitize=leak` flag. Make sure to use `clang` (not `ld`) for the link step, so that it would link in proper LeakSanitizer run-time library into the final executable.

## More Information

https://github.com/google/sanitizers/wiki/AddressSanitizerLeakSanitizer