[Issue 3797] Implicit conversion between incompatible function pointers

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=3797



--- Comment #5 from yebblies <yebblies at gmail.com> 2010-10-18 19:29:40 PDT ---
(In reply to comment #4)
> Is this a cross-platform bug?

Yes.  The problem is that pointers to functions with different calling
conventions and parameters can be implicitly converted to each other.  This can
easily cause stack corruption and/or corrupted parameters.  This is not unique
to any platform.

------------------------------

import std.stdio;
import std.typetuple;

extern(D)
{
    void d1() { writeln("d1"); }
    void d2(int a) { writeln("d2(", a, ")"); }
    void d3(int a, int b) { writeln("d3(", a, ", ", b, ")"); }
    void d4(long a, long b) { writeln("d4(", a, ", ", b, ")"); }
}
extern(C)
{
    void c1() { writeln("c1"); }
    void c2(int a) { writeln("c2(", a, ")"); }
    void c3(int a, int b) { writeln("c3(", a, ", ", b, ")"); }
    void c4(long a, long b) { writeln("c4(", a, ", ", b, ")"); }
}
extern(Windows)
{
    void w1() { writeln("w1"); }
    void w2(int a) { writeln("w2(", a, ")"); }
    void w3(int a, int b) { writeln("w3(", a, ", ", b, ")"); }
    void w4(long a, long b) { writeln("w4(", a, ", ", b, ")"); }
}
extern(C++)
{
    void cpp1() { writeln("cpp1"); }
    void cpp2(int a) { writeln("cpp2(", a, ")"); }
    void cpp3(int a, int b) { writeln("cpp3(", a, ", ", b, ")"); }
    void cpp4(long a, long b) { writeln("cpp4(", a, ", ", b, ")"); }
}
extern(Pascal)
{
    void p1() { writeln("p1"); }
    void p2(int a) { writeln("p2(", a, ")"); }
    void p3(int a, int b) { writeln("p3(", a, ", ", b, ")"); }
    void p4(long a, long b) { writeln("p4(", a, ", ", b, ")"); }
}

void main()
{
    size_t stack;

    asm { mov stack, ESP; }
    writeln(stack);

    alias TypeTuple!(d1, d2, d3, d4, c1, c2, c3, c4, w1, w2, w3, w4, cpp1,
cpp2, cpp3, cpp4, p1, p2, p3, p4) functions;

    auto fptr = &d3;

    foreach(f; functions)
    {
        fptr = &f;
        fptr(1, 2);
    }

    asm { mov stack, ESP; }
    writeln(stack);
}

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