[Issue 19563] New: extern(C++) Incorrect ABI passing small struct

d-bugmail at puremagic.com d-bugmail at puremagic.com
Wed Jan 9 08:22:47 UTC 2019


          Issue ID: 19563
           Summary: extern(C++) Incorrect ABI passing small struct
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: blocker
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: turkeyman at gmail.com


struct Test
    Test() : ptr(nullptr) {}
    Test(const Test& x)
        ptr = x.ptr + 10;
    char* ptr;

int test(Test p);

int main()
    Test x;
    return 0;



struct Test
        ptr += 10;
    char* ptr;

int test(Test p)
    assert(p.ptr == null);
    return 10;


When I build and run this, passing `x` to test() by value crashes. The function
receives garbage.

If you remove the copy constructors (pass this same struct as a POD), it works

This was tested in Linux 64bit, against GCC-7.
If it makes any difference, I supplied `-std=c++11 -D_GLIBCXX_USE_CXX11_ABI=0`
to the C compiler.


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