• via Digitalmars-d-bugs (52/52) Nov 23 2014 https://issues.dlang.org/show_bug.cgi?id=13769

via Digitalmars-d-bugs <digitalmars-d-bugs puremagic.com> writes:

https://issues.dlang.org/show_bug.cgi?id=13769

          Issue ID: 13769
           Summary: Wrong argument passing for variadic functions in 64
                    bits
           Product: D
           Version: D2
          Hardware: x86_64
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: DMD
          Assignee: nobody puremagic.com
          Reporter: pro.mathias.lang gmail.com

The following code:
````
private unittest {
  import core.vararg, std.stdio;
  void fix() {}

  void test_bug(size_t bug, ...) { assert(bug == size_t.max); }
  void test_fixed(size_t bug, ...) { fix(); assert(bug == size_t.max); }
  void print_bug(size_t bug, ...) { writeln(bug); assert(bug == size_t.max); }
  void print_fix(size_t bug, ...) { fix(); writeln(bug); assert(bug ==
size_t.max); }

  print_bug(size_t.max);
  print_fix(size_t.max);
  test_fixed(size_t.max);
  test_bug(size_t.max);
}
````

Will trigger an unittest when put any Phobos module (for simplicity, I tested
std.algorithm).

Example:
````
make[1]: Leaving directory '/mnt/shared/projects/dlang/druntime'
140734760252720
18446744073709551615
****** FAIL std.algorithm
core.exception.AssertError std/algorithm.d(417): Assertion failure
----------------
generated/linux/release/64/unittest/libphobos2-ut.so(+0x28fb8e1)
[0x7f2bf2fcd8e1]
````

As you see, the parameters passed during the first function call inside that
function are wrong. I only appears with 64 bits parameters (including string).

I couldn't find any stand-alone snippet that reproduce the error. My guess is
that it might originate from the way it's tested (shared library), but I
currently lack the time to investigate further.

The issue was originally found in
https://github.com/D-Programming-Language/phobos/pull/2677

This also outline the fact that variadic functions are poorly tested in Phobos.

--