[cfe-dev] Function return not catching the undefined behavior

[Jessica Clarke via cfe-dev]

This is implementation-defined, not undefined. C99 6.3.1.3p3:

  Otherwise, the new type is signed and the value cannot be represented in it; either the result is implementation-defined or an implementation-defined signal is raised.

Jess

> On 21 Jan 2022, at 07:16, Craig Topper via cfe-dev <cfe-dev at lists.llvm.org> wrote:
> 
> I'm not sure that is undefined behavior, but it is caught by -fsanitize=integer
> 
> ~Craig
> 
> 
> On Thu, Jan 20, 2022 at 11:06 PM phy coder via cfe-dev <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
> And if I'm wrong or misunderstand something then please let me know.
> 
> On Fri, Jan 21, 2022, 12:00 phy coder <coderphy3 at gmail.com <mailto:coderphy3 at gmail.com>> wrote:
> I'm not sure if this is undefined behavior or not and it may be discussed before or not. I was testing some random code snippets to try "-fsanitize=undefined" but in this example:
> 
> #include<iostream>
> 
> char func(int a, int b) {
>     int sum = a+b;
>     return sum ;
> }
> 
> int main() {
>     int n;
>     char s = func(100,100);
>     int t = func(100,100);
>    std::cout << "hello" << s << t;
>   return 0;
> 
> }
> 
> I was expecting some kind of undefined behavior here because of some overflowing the char return type with integer return type. But "-fsanitize=undefined" is not able to catch this . And I got the output this : hello�-56 
> Kinda weird for me . 
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