https://issues.dlang.org/show_bug.cgi?id=19521
Issue ID: 19521
Summary: @safe typesafe_variadic_functions could cause memory
corruption
Product: D
Version: D2
Hardware: x86
OS: Windows
Status: NEW
Severity: major
Priority: P1
Component: dmd
Assignee: [email protected]
Reporter: [email protected]
The below snippet runs and works fine, but likely only because the compiler
doesn't do the optimisation which the spec explicitly allows.
"An implementation may construct the object or array instance on the stack.
Therefore, it is an error to refer to that instance after the variadic function
has returned"
https://dlang.org/spec/function.html#typesafe_variadic_functions
There are many possible fixes
1) Allow DIP25 style return annotation even if there is no 'ref'.
2) Compilation error
3) Change spec to disallow optimisation
void main()
{
auto x1 = fun(1);
auto x2 = fun(2);
import std.stdio;
writeln(x1.a, x2.a);
}
@safe:
class C
{
public:
int a;
this(int a) { this.a = a; }
}
C fun(/* return */ C c...)
{
return c;
}
--
