Because that is undefined behavior for x == INT_MAX, and if the compiler is detecting undefined behavior and emitting errors, this would be an obvious candidate.
How about this simple function?
int Divide(int x, int y) { return x / y; }
This is undefined behavior for y == 0, or for x == -INT_MAX - 1 and y == -1. Shall it produce an error?
(Never mind why you're writing such simple functions. Imagine they do something more complex and just do the division or addition or whatever as part of their work.)
This will invoke undefined behavior if passed a string constant as its parameter, or if passed an array that doesn't have a 0 in it. There is no portable (i.e. without invoking undefined behavior) way to check whether the parameter is a string constant or doesn't have a 0, so it is impossible to assert away the undefined behavior for this.
Many real, practical, production-worthy C functions will invoke undefined behavior with some inputs. Turning undefined behavior into a compile-time error will cause virtually all C code to not compile.
"There is no portable way to check whether the parameter is a string constant"
Well, the compiler should warn you if you try to pass a (char const ＊) to a function expecting a (char ＊). Use -Wwrite-strings to make string literals have type (char const[]) rather than (char[]).
How about this simple function?
This is undefined behavior for y == 0, or for x == -INT_MAX - 1 and y == -1. Shall it produce an error?(Never mind why you're writing such simple functions. Imagine they do something more complex and just do the division or addition or whatever as part of their work.)
Here's a fun one:
This will invoke undefined behavior if passed a string constant as its parameter, or if passed an array that doesn't have a 0 in it. There is no portable (i.e. without invoking undefined behavior) way to check whether the parameter is a string constant or doesn't have a 0, so it is impossible to assert away the undefined behavior for this.Many real, practical, production-worthy C functions will invoke undefined behavior with some inputs. Turning undefined behavior into a compile-time error will cause virtually all C code to not compile.