[loeg]

You're being unnecessarily combative.

> No. You are wrong. There are no words in the standard that say that “basic types cannot overlap in memory”.

§ J.2, Undefined Behavior

An object is assigned to an inexactly overlapping object or to an exactly overlapping object with incompatible type (6.5.16.1).

> There is not even a notion of “basic type”.

"Object."

You repeatedly (in this thread, and on your blog) express that you don't really understand "strict" (ISO standard) aliasing rules, and that seems to be the case.

[pascal_cuoq]

This line of J.2 only refers to the already cited 6.5.16.1.

You keep quoting this clause as if it applied to any of the assignments in the program being discussed.

It doesn't.

That clause says that in an assignment of the form “lvalue1 = lvalue2;”, there must only be exact overlap or no overlap between lvalue1 and lvalue2. This does not apply to assignments of the form “lvalue = 1;” or “lvalue = 2;” which are the interesting assignments in the program being discussed.

Objects are not “basic types” for the original sentence that claimed that “basic types cannot overlap in memory”. Objects overlap in memory all the time.

> You repeatedly (in this thread, and on your blog) express that you don't really understand "strict" (ISO standard) aliasing rules, and that seems to be the case.

If you say so. I'm not the one who thinks that “* p” and “1” overlap.

[loeg]

> You keep quoting this clause as if it applied to any of the assignments in the program being discussed.

> It doesn't.

You keep asserting that 6.5.16.1 is not relevant, as if it makes it so; but it doesn't. It's your opinion; the assertions are not persuasive.

  void f(void) {
    char *t = malloc(1 + sizeof(int));
    if (!t) abort();
    int *fp = (int*)t;
    int *fq = (int*)(t+1);
    h(fp, fq);

  int h(int *p, int *q){
    *p = 1;
    *q = 1;
    return *p;
  }

Please explain to me why you continue to believe that is not an object being assigned to an inexactly overlapping object or to an exactly overlapping object with incompatible type?

[pascal_cuoq]

Please explain to me why you think it is.

The clause says:

“If the value being stored in an object is read from another object that overlaps in any way the storage of the first object, then the overlap shall be exact and the two objects shall have qualified or unqualified versions of a compatible type; otherwise, the behavior is undefined.”

Under “6.5.16.1 Simple assignment”, so this describes a rule about assignment.

Which assignment in the program are you claiming stores in an object a value read from another object that overlaps in any way the storage of the first object?