RFA/RFC: Add stack recursion limit to libiberty's demangler

[Joseph Myers]

On Sat, 1 Dec 2018, Cary Coutant wrote:

> In order to handle arbitrary user input without crashing, perhaps the
> demangler should switch from recursive descent parsing to a state
> machine, where exhaustion of resources can be handled gracefully.

I've wondered if a GCC C/C++ extension could be defined that means 
"convert this set of mutually recursive functions into a single function 
with a state machine that allocates the equivalent of the stack manually".  
But such an extension would certainly be nontrivial to define.  (One use 
for such an extension would be to avoid the GCC bugs that occasionally get 
reported of the form "expressions with a million nested pairs of 
parentheses make the compiler segfault", by using it to avoid recursion in 
the parsers.)

-- 
Joseph S. Myers
joseph@codesourcery.com