[Saw a response here, but it disappeared before my reply. Posted here anyway in case it clarifies my first paragraph.] Did you check out the link? https://god

[Saw a response here, but it disappeared before my reply. Posted here anyway in case it clarifies my first paragraph.] Did you check out the link? https://godbolt.org/g/aaC4B7 https://godbolt.org/g/aaC4B7 My surprise is that none of clang, gcc, or icc give any warning on this with -Wall -Wextra: 1 void copy_const(const int * const arg) { 2 int *copy = (int *)arg; 3 (*copy)++; 4 } I agree that the cast on line 2 is legal and requires no warning. My surprise is that there is no warning for the write on line 3, since I think this is undefined behavior according the quoted part of the spec. Isn't this trying "to modify an object defined with a const-qualified type through use of an lvalue with non-const-qualified type"? I realize that the compiler has no obligation to issue a warning here, and in fact is fully entitled to my first-born as soon as it encounters undefined behavior. Still, it seems like it would be a useful place to offer the user a warning just as it does in the case of direct modification: 1 void write_const(const int * const arg) { 2 (*arg)++; 3 } clang: "error: read-only variable is not assignable" gcc: "error: increment of read-only location '*arg'" icc: "error #137: expression must be a modifiable lvalue"