this program crash with clang
#include <iostream>
#include <string>
#include <mutex>
#include <functional>
int main(int argc, char **argv)
{
auto m = std::function<void()>( [](){
int r = std::rand() % 100;
if (r < 50)
{
return r; //should not return
}
});
for(int i=0;i<100;i++)
m();
return 0;
}
reports:
pt@test$ clang++ -o test test1.cpp -std=c++11
test1.cpp:14:5: warning: control may reach end of non-void lambda [-Wreturn-type]
});
^
1 warning generated.
pt@test$ ./test
Illegal instruction (core dumped)
but, it doesn't crash with g++.
My confusion is that since it will cause an crashing, why not clang treat it as an error while compiling?
update
consider following code
auto lMayNotReturn = []() {
int rValue = std::rand() % 100;
if (rValue < 50)
{
return rValue; //should not return
}
std::cout << " non-return rValue: " << rValue << std::endl;
};
for(int i=0 ; i< 30;i++){
int rValue= lMayNotReturn();
std::cout << "random value " << rValue << " ";
if (rValue >= 50) {
std::cout << " ???undefined???";
}
std::cout << std::endl;
}
std::cout << "end--------" << std::endl;
targets generated by gcc & visual studio will keep running and return random values as
pt@DESKTOP-S54JIQA:/mnt/e/Projects/uv_test$ ./test
non-return rValue: 83
random value 6295680 ???undefined???
non-return rValue: 86
random value 6295680 ???undefined???
non-return rValue: 77
random value 6295680 ???undefined???
Bugs like this are far more difficult to track down than simply crashing and clang wins.
The only reason for clang not raising an error that I can think of is compatibility.
