Are there sequence points in braced initializer lists when they apply to constructors?

Question

According to the n4296 C++ standard document:

[dcl.init.list] (8.5.4.4) (pg223-224)

Within the initializer-list of a braced-init-list, the

Answer 1

This note is not related to evaluation order. As it was stated in one of comments, it's about order of converting actual parameters to rvalues and standard does not define such order. You should receive following warning (gcc):

17:58: warning: operation on 'i' may be undefined [-Wsequence-point]

I modified a program slightly to demonstrate how evaluation of arguments work with {} and ().

With such modification, program does not depend on order of converting lvalue to rvalue, thus does not have ambiguity which disappointed you.

#include 

struct MyType {
  MyType(int i, int j)
    : sum(i + j)
  {

  }

  int sum;
};

int main()
{
  int i = 0;
  int a,b;
  std::cout << MyType{ (a = ++i), (b = ++i) }.sum << '\n';
  std::cout << "Here clauses are evaluated in order they appear: a=" << a << ", b=" << b << std::endl;
  i = 0;
  std::cout << MyType( (a = ++i), (b = ++i) ).sum << '\n';
  std::cout << "Here order of evaluation depends on implementation: a=" << a << ", b=" << b << std::endl;
}

And the output of this program for clang and gcc:

clang:

3
Here clauses are evaluated in order they appear: a=1, b=2
3
Here order of evaluation depends on implementation: a=1, b=2

gcc:

3
Here clauses are evaluated in order they appear: a=1, b=2
3
Here order of evaluation depends on implementation: a=2, b=1

As you can see, in case of curly brackets, clauses are evaluated in order of appearance under both compilers, which corresponds to the note you provided.