[Issue 15851] New: Access violation when foreaching variadic template argument tuple
via Digitalmars-d-bugs
digitalmars-d-bugs at puremagic.com
Wed Mar 30 05:35:49 PDT 2016
https://issues.dlang.org/show_bug.cgi?id=15851
Issue ID: 15851
Summary: Access violation when foreaching variadic template
argument tuple
Product: D
Version: D2
Hardware: x86_64
URL: http://dlang.org/
OS: All
Status: NEW
Severity: normal
Priority: P3
Component: dmd
Assignee: nobody at puremagic.com
Reporter: sunspyre at gmail.com
The long description: Access violation when dereferencing a field in a foreach
of a variadic template argument tuple, when inside a switch case.
dmd is v2.070.2 from the official installer, and the machine is running Windows
8. ldc2 0.17.1 exhibits the same behaviour. Could not test gdc because of
difficulty of installation.
Reduced example (http://dpaste.dzfl.pl/ee9a4503f6f5):
-----------------------
import std.stdio;
version = broken;
struct Foo
{
string abc;
int def;
}
void walkArgumentTuple(T...)(ref T tup)
{
top:
final switch (0)
{
foreach (i, ref thing; tup)
{
// thing is invalid for some reason
// but the below doesn't fail
assert(thing is tup[i]);
case 0:
version(broken)
{
// object.Error@(0): Access Violation
writeln(thing);
}
else
{
// works
writeln(tup[i]);
}
break top;
}
}
}
void main()
{
Foo f;
walkArgumentTuple(f);
}
-----------------------
All tested compilers accept and compile this. It behaves differently depending
on the number (and maybe type) of members of the Foo struct. Likewise if
compiled with or without -m64, and whether parameters are marked as ref or not.
In many combinations it won't error out, but instead spam the screen with
garbage in hex. See the dpaste linked earlier, with version = dpastefreaksout
uncommented.
Foo(x"10 1C 00 00 00 00 00 00 7C FD 45 [... ad nauseam]
I have also had it spout out semi-intelligible things removing ref from
everything, but dpaste can't seem to reproduce that.
Foo("\x04\x10\0\0\0\0\0\0gc.config\0src\\gc\\config.d\0\0\0\0\0", 0)
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