Bug 6419 – [CTFE] Cannot create a non-static nested struct

Test case 1: ---------------------- static assert({ struct Result { this(int x) {} } auto x = Result(1); // <-- line 5 return true; }()); ---------------------- x.d(5): Error: CTFE internal error assigning struct x.d(7): Error: cannot evaluate delegate @system bool() { struct Result { this(int x) { return this; } void* this; } Result x = x = 0 , x.this(1); return true; } () at compile time ... ---------------------- Test case 2 (causes ICE): ---------------------- static assert(({ struct Result { this(int x) {} } return Result(1); }(), true)); ---------------------- x.d(6): Error: CTFE internal error assigning struct Bus error: 10 ---------------------- This bug affects using std.algorithm.map in CTFE, although I don't see any point keeping that constructor any more.

*** Issue 6460 has been marked as a duplicate of this issue. ***

This is because if the struct is nested, TypeStruct::defaultInitLiteral() doesn't return a literal!

The bug which caused an ICE was independent to this one, and has been fixed.

*** Issue 6653 has been marked as a duplicate of this issue. ***

Actually, it doesn't need a constructor. The presence of _any_ member function triggers the bug: static assert({ struct Result { void foo(){} } Result x; return true; }()); If it doesn't have any member functions, then it is actually a static nested struct. So true nested structs are never supported in CTFE. It's because the hidden member of the struct needs a pointer to the enclosing function, and this is not implemented.

This is sad because you can't do compile-time FizzBuzz :) ------------------- import std.stdio, std.conv, std.range, std.algorithm; void main() { enum fizzbuzz = iota(1, 100) .map!(x => (0 == x % 15) ? "FizzBuzz" : (0 == x % 5) ? "Buzz" : (0 == x % 3) ? "Fizz" : to!string(x)) .joiner("\n"); writeln(fizzbuzz); } -------------------

All the test-case provided here work in 2.061.