Bug 20993 – spec claims extern(C) and extern(D) function are identical

The spec on the ABI claims that "The extern (C) and extern (D) calling convention matches the C calling convention used by the supported C compiler on the host system." https://dlang.org/spec/abi.html#function_calling_conventions On MacOS, however, the calling convention of even 2 int parameters is different: --- foo.c #include <stdio.h> void foo(int a, int b) { printf("a=%d b=%d\n", a, b); } --- main.d pragma(mangle, "foo") extern (D) void foo_extern_d(int, int); pragma(mangle, "foo") extern (C) void foo_extern_c(int, int); void main() { foo_extern_d(1, 2); foo_extern_c(1, 2); } --- gcc -c foo.c dmd main.d foo.o ./main a=2 b=1 a=1 b=2 Clearly, the arguments are passed in a different order depending on whether the function is extern(C) or extern(D). Either the spec should be updated, or the compiler should be modified to match the spec.

*** This issue has been marked as a duplicate of issue 20204 ***