Compiling this code for COFF with "dmd -m64 -g":

module dbgi;

__gshared int recurse;

int foo(int n)
{
	recurse++;
	scope(exit)
	{
		recurse--;
		if (recurse < 0)
			assert(false);
	}
	int r = n + n;
	int s = r + 2;
	return r;
}

void main()
{
	int x = foo(7);
}

yields missing debug line information for the code in scope(exit), e.g. disassembly in VS looks like this:

     5: int foo(int n)
00007FF797F0BF80  push        rbp  
00007FF797F0BF81  mov         rbp,rsp  
00007FF797F0BF84  sub         rsp,18h  
00007FF797F0BF88  push        rbx  
00007FF797F0BF89  mov         dword ptr [n],ecx  
     6: {
     7: 	recurse++;
00007FF797F0BF8C  inc         dword ptr [dbgi.recurse (07FF79800A4A0h)]  
     8: 	scope(exit)
     9: 	{
    10: 		recurse--;
    11: 		if (recurse < 0)
    12: 			assert(false);
    13: 	}
    14: 	int r = n + n;
00007FF797F0BF92  mov         eax,dword ptr [n]  
     8: 	scope(exit)
     9: 	{
    10: 		recurse--;
    11: 		if (recurse < 0)
    12: 			assert(false);
    13: 	}
    14: 	int r = n + n;
00007FF797F0BF95  mov         ecx,eax  
00007FF797F0BF97  lea         edx,[rax+rcx]  
00007FF797F0BF9A  mov         dword ptr [r],edx  
    15: 	int s = r + 2;
00007FF797F0BF9D  lea         ebx,[rdx+2]  
00007FF797F0BFA0  mov         dword ptr [s],ebx  
00007FF797F0BFA3  mov         eax,edx  
00007FF797F0BFA5  mov         qword ptr [rbp-10h],rax  
00007FF797F0BFA9  sub         rsp,8  
00007FF797F0BFAD  call        dbgi.foo+4Fh (07FF797F0BFCFh)  
00007FF797F0BFB2  add         rsp,8  
00007FF797F0BFB6  mov         rax,qword ptr [rbp-10h]  
00007FF797F0BFBA  pop         rbx  
00007FF797F0BFBB  mov         rsp,rbp  
00007FF797F0BFBE  pop         rbp  
00007FF797F0BFBF  ret  
00007FF797F0BFC0  sub         rsp,8  
00007FF797F0BFC4  call        dbgi.foo+4Fh (07FF797F0BFCFh)  
00007FF797F0BFC9  add         rsp,8  
00007FF797F0BFCD  jmp         dbgi.foo+76h (07FF797F0BFF6h)  
00007FF797F0BFCF  dec         dword ptr [dbgi.recurse (07FF79800A4A0h)]  
00007FF797F0BFD5  cmp         dword ptr [dbgi.recurse (07FF79800A4A0h)],0  
00007FF797F0BFDC  jns         dbgi.foo+75h (07FF797F0BFF5h)  
00007FF797F0BFDE  mov         edx,0Ch  
00007FF797F0BFE3  lea         rcx,[__a6_646267692e64 (07FF797FF7E20h)]  
00007FF797F0BFEA  sub         rsp,20h  
00007FF797F0BFEE  call        _d_assertp (07FF797F0643Dh)  
00007FF797F0BFF3  ud2  
00007FF797F0BFF5  ret  
    16: 	return r;
    17: }
00007FF797F0BFF6  pop         rbx  
    16: 	return r;
    17: }
00007FF797F0BFF7  mov         rsp,rbp  
00007FF797F0BFFA  pop         rbp  
00007FF797F0BFFB  ret  

This prevents setting breakpoints in the scope(exit)-code or stepping through the code.