c++ - Problem with Tail Recursion in g++ -

i'm messing around tail-recursive functions in c++, , i've run bit of snag g++ compiler.

the following code results in stack overflow when numbers[] on couple hundred integers in size. examining assembly code generated g++ following reveals twosum_helper executing recursive call instruction itself.

the question of following causing this?

• a mistake in following overlooking prevents tail-recursion.
• a mistake usage of g++.
• a flaw in detection of tail-recursive functions within g++ compiler.

i compiling g++ -o3 -wall -fno-stack-protector test.c on windows vista x64 via mingw g++ 4.5.0.

struct result {     int i;     int j;     bool found; };  struct result gen_result(int i, int j, bool found) {     struct result r;     r.i = i;     r.j = j;     r.found = found;     return r; }  // return 2 indexes numbers sum target. struct result twosum_helper(int numbers[], int size, int target, int i, int j) {     if (numbers[i] + numbers[j] == target)         return gen_result(i, j, true);     if (i >= (size - 1))         return gen_result(i, j, false);     if (j >= size)         return twosum_helper(numbers, size, target, + 1, + 2);     else         return twosum_helper(numbers, size, target, i, j + 1); } 

tail call optimization in c or c++ extremely limited, , pretty lost cause. reason there no safe way tail-call function passes pointer or reference local variable (as argument call in question, or in fact other call in same function) -- of course happening on place in c/c++ land, , impossible live without.

the problem seeing related: gcc compiles returning struct passing address of hidden variable allocated on caller's stack callee copies -- makes fall above scenario.