We cannot use std.exception.enforceEx in @safe function.

import std.exception;
void test1() @safe
{
    enforceEx!Exception(true, "");
    // Error: safe function 'test1' cannot call system function 'enforceEx'
}

This is dmd bug, using lazy parameter is inferred as unsafe, so whole enforceEx calling is inferred as unsafe.

More simple test case.

T useLazy(T)(lazy T val)
{
    return val;
}
void test2() @safe
{
    useLazy(0);
    // Error: safe function 'test2' cannot call system function 'useLazy'
}