405256 - Compile error in nsNativeDragTarget.h with MingW GCC because of missing shobjidl.h

Status: RESOLVED FIXED

(Core :: Widget: Win32, defect)

Description

[jfwfreo]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.9) Gecko/20071030 SeaMonkey/1.1.6
Build Identifier: 

MingW does not include shobjidl.h which prevents nsNativeDragTarget.h from compiling. Fix is to not #include shobjidl.h on MingW GCC (doing so allows compilation to succeed)


Reproducible: Always

Comment 1

[jfwfreo]

Attachment: possible patch

Possible patch.

Comment 2

[jfwfreo]

Is this patch the correct solution or is there a better way (e.g. getting a shobjidl.h into MingW)?

Comment 3

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Getting shobjidl.h into MingW would be good but until then we should fix our code.

 //MingW does not provide shobjidl.h. Code compiles fine without it however

Why don't we just remove it altogether then? Is it because you're not building on Vista? What if someone tries to do a MingW build on Vista?

Comment 4

[jfwfreo]

VC8 and MingW both define IDropTargetHelper in shlobj.h. The Microsoft SDK I have installed (which labels itself v6.0) moves it to shobjidl.h. Ergo, even if you built on Vista with all the WINVER settings to make that happen, it would still build just fine with VC8 and MingW.

The question is, given that shlobj.h on MingW provides IDropTargetHelper, why is it still trying to #include shobjidl.h? Is _WIN32_IE not being defined properly?

Comment 5

[Robert O'Callahan (:roc) (email my personal email if necessary)]

I don't know, you'll have to find out. I'd try using -E to preprocess the source to see what's getting defined. 

Comment 6

[Sergey Fukanchik]

> The question is, given that shlobj.h on MingW provides IDropTargetHelper, why
is it still trying to #include shobjidl.h?
Because IDropTargetHelper isn't #defined in preprocessor but declared in c code. And that is why it's not visible to preprocessor #ifdef. Preprocessor knows nothing about c/c++.

It's stupid to check for c/c++ declaration using preprocessor condition:
nsNativeDragTarget.h:45:
#ifndef IDropTargetHelper

Preprocessor sees only declarations from earlier #defines and -D command line options.

That is why even after #include <shobjidl.h> "#ifndef IDropTargetHelper" will still succeed.

DECLARE_INTERFACE_(IDropTargetHelper, IUnknown) after preprocessing will become:

struct __attribute__((com_interface)) IDropTargetHelper : public IUnknown

and again IDropTargetHelper will be not visible to preprocessor.

Certainly this is error.

Comment 7

[Bengt-Erik Soderstrom]

Attachment: Possible patch ver 2

Comment 8

[Bengt-Erik Soderstrom]

About a week ago, in bug 418658, a similar fix regarding WinCE was checked in.
If that could be done, I then think also letting MinGW exclude shobjidl.h should be allowed.

Changing the status to NEW and attach a new possible patch

Comment 9

[Damon Sicore (:damons)]

Comment on attachment 306468 [details] [diff] [review]
Possible patch ver 2

a1.9+=damons

Comment 10

[Bengt-Erik Soderstrom]

I am not authorized to make cvs check-ins, perhaps someone else can help?
Benjamin? Martijn?

Comment 11

[Martijn Wargers (dead)]

Reed is normally pretty quick when the bug has the "checkin-needed" keyword (thanks Reed!). Otherwise I can check this in tonight. 

Comment 12

[Reed Loden [:reed]]

Checking in widget/src/windows/nsNativeDragTarget.h;
/cvsroot/mozilla/widget/src/windows/nsNativeDragTarget.h,v  <--  nsNativeDragTarget.h
new revision: 1.15; previous revision: 1.14
done