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delphidelphi-xe6

Delphi compiler warning for passing signed to unsigned

I recently tried using Range Checking in my application, in an attempt to catch array bounds violations, etc.

Unfortuantly this has caused quite a few non-errors relating to HRESULT:

var
    hr: HRESULT;
begin
    hr := E_UNEXPECTED;
    ShowMessage(SysErrorMessage(hr));

The call to SysErrorMessage fails with a ERangeError. That is because:

HRESULT = type Longint;  { from wtypes.h }

function SysErrorMessage(ErrorCode: Cardinal): string;

Manually typecast

The solution is simple: manually force a conversion to Cardinal every time i pass an HRESULT to SysErrorMessage.

This works well enough for code in the current project i'm working on - do a search for SysErrorMessage and scan the results for where I might be passing an HRESULT:

enter image description here

But it fails when there is code in shared libraries. And it also fails when there might be other constructs where i'm passing a signed to unsigned and vice versa.

Can the compiler just tell me?

Does the compiler have a warning option to catch when i mix signed and unsigned types? Obviously i'm going to disable the use of range checking.

See also

Bonus

All the WinSock functions return Integer:

int WSAAPI getaddrinfo(
  _In_opt_       PCSTR      pNodeName,
  _In_opt_       PCSTR      pServiceName,
  _In_opt_ const ADDRINFOA  *pHints,
  _Out_          PADDRINFOA *ppResult
);

and 

int WSAGetLastError(void);

Jcl/Jvcl has a lot of fixin to be doin.

Solution

  • Does the compiler have a warning option to catch when i mix signed and unsigned types?

    W1024 will collect mixed arithmetic and comparisons. But there's nothing at compile time for assignment or parameter passing, which is essentially the same as assignment.