[RFC] std::vector and std::string ASan annotations design

[Ivan Baravy]

Hello,

libc++ has a feature of ASan annotations inside std::vector [1,2] and 
std::string [3]. These make it possible to detect container overflows, 
i.e. accesses between its size and capacity. I also noticed similar 
approach to libstdc++ [4], unfinished though. I really like the idea to 
have this feature in libstdc++ and I prepared patches providing the 
annotations mostly based on libc++ code. However, while this development 
I faced a design issue I want to discuss with you.

In libc++, all the string's API functions are defined in corresponding 
header file. This allows ASan annotations to be placed there (and only 
there) and thus not affect dso binary. In libstdc++, instead, 
basic_string.h has both definitions and declarations of public API 
functions. Therefore I had to put some ASan annotations into 
basic_string.tcc file which becomes a part of libstdc++ binary.

As a result,
  - Sanitized applications require sanitized libstdc++ to run, and vice 
versa;
  - Sanitized libstdc++ requires all applications and libraries using 
std::string to be sanitized.

The only solution I see for now is to move definitions into 
basic_string.h in libc++ manner. However this is not acceptable for 
upstream, I assume, which is my aim. Could you suggest a better solution 
or give me any pointers on the issue?

Thank you.

Regards,
Ivan

[1] 
http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20140505/104822.html
[2] 
http://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20140901/113973.html
[3] https://reviews.llvm.org/D12577
[4] https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=207517