Environment:
Framework: Qt 5.12.9
Compiler: MSVC 15.9.28307.1234 (x64)
Debugger: CDB 10.017763.132 (x64)
Standard: C++11
Editor: Qt Creator 4.12.2
OS: Win10 Enterprise 1809
I want to develop an application that can be expanded through plug-ins. Therefore I created a standard library project where I want to define the plug-in interfaces. This library should then be consumed by the main application and its plug-ins.
I read about the Qt plug-in system on the official websites and sought help by duckduckgo-ing, but I'm stuck with these following errors:
vccplugin.h:16:32: error: expected parameter declarator
vccplugin.h:14:23: note: expanded from macro 'VccPlugin_iid'
vccplugin.h:16:32: error: expected ')'
vccplugin.h:14:23: note: expanded from macro 'VccPlugin_iid'
vccplugin.h:16:20: note: to match this '('
vccplugin.h:16:1: error: C++ requires a type specifier for all declarations
Build Issue: C2059: syntax error: 'string'
This is the code:
#ifndef VCCPLUGIN_H
#define VCCPLUGIN_H
#include "VccPluginInterface_global.h"
class VCCPLUGININTERFACE_EXPORT VccPlugin
{
public:
VccPlugin();
~VccPlugin();
void DoeEenTwuk();
};
#define VccPlugin_iid "automation.general.vcc.interface"
Q_DECLARE_INTERFACE(VccPlugin, VccPlugin_iid);
#endif // VCCPLUGIN_H
Also note, I have little experience in both C++ and Qt.
Any help very appreciated,
thanks
I have found the issue. The problem is that the compiler couldn't find the macro, so all I had to add was:
#include <QtPlugin>
Since Q_DECLARE_INTERFACE is defined in QtPlugin. Your example didn't import QtPlugin but was probably imported implicit by another import, probably QMainWindow.
It would have been simpler if I got an error like: "Could not find symbol Q_DECLARE_INTERFACE" if you ask me. Especially since I'm rather blue in this topic.
Thanks for your support #NgocMinhNguyen and others
Related
Trying to build Tink library (https://github.com/google/tink) with Bazel. Bazel installed, gcc version 7.2.0, Windows 10 x64. Visual C++ 2017.
At first, there were errors like "C++ compilation of rule '#boringssl//:crypto' failed" - I commented these lines (with compilation flags I think) in boringssl/BUILD file (sections boringssl_copts, boringssl_copts_c11) and they disappeared.
But after that, bazel said, that error is in errors.h file (https://github.com/google/tink/blob/master/cc/util/errors.h)
// from #include "absl/base/port.h"
#define PRINTF_ATTRIBUTE(string_index, first_to_check) \
__attribute__((__format__ (__printf__, string_index, first_to_check)))
// Constructs a Status object given a printf-style va list.
crypto::tink::util::Status ToStatusF(
crypto::tink::util::error::Code code, const char* format, ...)
PRINTF_ATTRIBUTE(2, 3);
} // namespace tink
} // namespace crypto
enter code here
Error C3646: unknown override specifier on line 32 (line with "PRINTF_ATTRIBUTE(2, 3);"). The most frightening thing is that in another files the same code (defining same attribute) is working.
There are another errors in this file, but mentioned is the first (and another are about the same line, so they are consequences of the first I guess).
I'm nearly a total newbie in cpp, but only cpp should be used, not java-version of library.
Thank you for your help, and sorry for possible misformatting and broken english - this is my first question here.
Unfortunately, we don't support Windows for now. It's something that we plan to support next year, please see our feature roadmap.
I am porting my tool to PIN 3.0 using Visual c++ 2012 because I now have Windows 10. I followed the porting guide provided here
However, I ran into an error:
error C4890: '__value': use of this keyword requires the command line option: /clr:oldSyntax
When turning this /clr:oldSyntax option on, plus adding RTTI availability (/GR instead of /GR-) as otherwise it is not compatible with /clr:oldSyntax, I get more or less the same issue:
error C2059: syntax error: '__value'
this error is located in the file type_trait.h (header file of the PIN 3.0 Library)
#ifdef _STLP_STATIC_CONST_INIT_BUG
static const bool __value;
#else
static const bool __value = sizeof(__test<_Tp>(0)) == sizeof(__select_types::__t1);
#endif
Is this a common issue, and if so is there any workaround ? Or did I missed something in the porting guide ? I understand that the name __value introduced in this PIN 3.0 header is in conclict.
This is apparently a "bug" in visual c++ as reported here
The solution is to add the following preprocessor definition:
/D__value=_value
WTL applications are quite small already. However, using VS 2005 a statically linked application with WTL 9.10 weighs in at 136 kB (139,264 Bytes) for the Win32 configuration.
Looking at the executable I noticed a static import of oleaut32.dll. A cursory look with dumpbin shows one import via ordinal.
OLEAUT32.dll
4181C0 Import Address Table
41C9B8 Import Name Table
0 time date stamp
0 Index of first forwarder reference
Ordinal 277
Inspecting oleaut32.dll one finds that the export is named VarUI4FromStr.
Digging a little with IDA, I found that VarUI4FromStr was used by ATL::CRegParser::AddValue. Following the dependents from there, showed two calls in ATL::CRegParser::RegisterSubkeys.
Cross-referencing the ATL code of my Visual Studio installation with the findings, I found that the culprit was ATL::CAtlComModule. It does a lot of TypeLib registration stuff that is simply not needed for my use case.
However, the linker seems to leave all of that in, because it cannot reasonably decide to throw it out.
How can I get rid of this seemingly superfluous import?
Alas, since WTL::CAppModule derives directly from ATL::CComModule, including the atlbase.h header while having _ATL_NO_COMMODULE defined leads to an error:
Error 1 fatal error C1189: #error : WTL requires that _ATL_NO_COMMODULE is not defined $(ProjectDir)\wtl\Include\atlapp.h 33
The actual culprit that ultimately pulls in ATL::CComModule is, however, ATL::CAtlComModule. So our goal is to get rid of both of them.
We'll try to trick atlbase.h into excluding all the TypeLib registration code by defining _ATL_NO_COMMODULE anyway, but undefining it right after we're done including it. This way atlapp.h and other WTL headers won't "notice".
#define _ATL_NO_COMMODULE
#include <atlbase.h>
#undef _ATL_NO_COMMODULE
#include <atlapp.h>
Obviously that gets us into some trouble:
1>atlapp.h(1515) : error C2039: 'CComModule' : is not a member of 'ATL'
1>atlapp.h(1515) : error C2504: 'CComModule' : base class undefined
1>atlapp.h(1524) : error C2653: 'CComModule' : is not a class or namespace name
1>atlapp.h(1543) : error C2653: 'CComModule' : is not a class or namespace name
1>atlapp.h(1625) : error C3861: 'GetModuleInstance': identifier not found
1>atlapp.h(1784) : error C2653: 'CComModule' : is not a class or namespace name
1>atlapp.h(1806) : error C2065: 'm_nLockCnt' : undeclared identifier
However, it looks like we should be able to fix this handful of errors quickly.
First of all let's check where ATL::CComModule comes from: it's declared and defined in atlbase.h. We can surely declare our own class and squeeze it in between #include <atlbase.h> and #include <atlapp.h> (see above).
Let's start with the basics, based on what can be found in atlbase.h:
namespace ATL
{
class CComModule : public CAtlModuleT<CComModule>
{
public:
CComModule() {}
};
};
Now we get a different set of errors:
1>atlapp.h(1524) : error C2039: 'Init' : is not a member of 'ATL::CComModule'
1> stdafx.h(31) : see declaration of 'ATL::CComModule'
1>atlapp.h(1625) : error C3861: 'GetModuleInstance': identifier not found
Excellent, so we're in fact only missing two more class functions: GetModuleInstance and Init. Let's pull those in as well. For good measure we'll also add GetResourceInstance:
namespace ATL
{
class CComModule : public CAtlModuleT<CComModule>
{
public:
CComModule() {}
HINSTANCE GetModuleInstance() throw() { return _AtlBaseModule.m_hInst; }
HINSTANCE GetResourceInstance() throw() { return _AtlBaseModule.m_hInstResource; }
HRESULT Init(_ATL_OBJMAP_ENTRY*, HINSTANCE, const GUID*) throw() { return S_OK; }
};
};
A short test proves that this is working fine. And the oleaut32.dll import is gone along with three more imports from ole32.dll. Great success!
And as a result we have saved 12 kB on the executable size.
Do you know other cool tricks to shrink WTL application size?
IMPORTANT
Note that depending on the features of ATL::CComModule which your code uses, you may have to fall back to using the original. The only other alternative is to extend the above mock version of ATL::CComModule to fix any compilation errors you may run into.
CAUTIONARY NOTE
I have not tested this extensively yet and I'll report back (by editing this answer) if I run into any trouble. However, from looking at it in both the ATL and WTL code as well as in the IDA database prior to my changes, I think this is a safe change.
Bonus trick
You may also use the 6001.18002 standalone WDK (for Vista SP1), which supports to target Windows 2000 (SP4) and newer. It includes ATL 7.0 and is therefore suited to build ATL+WTL applications.
To do that you just need to add the following two lines to your sources file:
USE_STATIC_ATL=1
ATL_VER=70
Thanks to the WDK, which uses msvcrt.dll, a system DLL, as its default (multithreaded dynamically linked) C runtime, you can then shrink the executable size further by linking dynamically to the C runtime. And in this case, since that particular C runtime is a system DLL (starting with Windows 2000), you can rest assured that it will work.
All of that taken into account you can build standard Windows applications (GUI or console) and DLLs that are really small.
Here is an example sources file which you can use as a template:
# Name of the program
TARGETNAME=progname
# Prefix used for the intermediate/output paths (e.g. objfre_w2k_x86)
TARGETPATH=obj
# A program, not a driver or DLL or static lib
TARGETTYPE=PROGRAM
# windows == GUI, console == Console, native == no subsystem ...
UMTYPE=windows
# Use Unicode ("wide char") instead of ANSI
UNICODE=1
# By default the WDK build treats warnings as errors - this turns it off
BUILD_ALLOW_ALL_WARNINGS=1
# Link dynamically to msvcrt.dll
USE_MSVCRT=1
# Don't link against any of the ATL DLLs
USE_STATIC_ATL=1
# In the 7600.16385.1 WDK you can use 70 as well, which translates to 71
ATL_VER=70
USE_NATIVE_EH=1
# RTTI is required for some ATL/WTL features
USE_RTTI=1
# GUI programs require these entry points
!IF defined(UNICODE) && $(UNICODE)
UMENTRY=wwinmain
C_DEFINES=$(C_DEFINES) /DUNICODE /D_UNICODE
!ELSE
UMENTRY=winmain
C_DEFINES=$(C_DEFINES) /DMBCS /D_MBCS
!ENDIF
# Include folders
INCLUDES=$(DDK_INC_PATH);$(CRT_INC_PATH);$(SDK_INC_PATH);wtl\Include
# Libraries to link to, not just import libraries
TARGETLIBS=\
$(SDK_LIB_PATH)\kernel32.lib \
$(SDK_LIB_PATH)\user32.lib \
$(SDK_LIB_PATH)\Comctl32.lib \
# Give source files (also resources and .mc) in the current or parent directory
SOURCES=...
The 7600.16385.1 standalone WDK also works for this. The WDKs starting from the Windows 8 WDK now require a Visual C++ into which they can be integrated. This also leads to the binaries requiring the respective C runtime version instead of the msvcrt.dll from prior WDK versions.
I created a simple program to learn how to use threading. This is the code i created
#include <iostream>
#include <stdlib.h>
#include <thread>
using namespace std;
void count_asc();
void count_desc();
int main() {
thread first(count_asc);
thread second(count_desc);
first.join();
second.join();
system("pause");
return 0;
}
void count_asc(){
int ctr;
for(ctr=1;ctr<=10;ctr++){
cout<<"First thread: "<<ctr<<endl;
}
}
void count_desc(){
int ctr;
for(ctr=10;ctr>=1;ctr--){
cout<<"Second thread: "<<ctr<<endl;
}
}
I am using Dev C++ 5.5.3. I have read other questions about this but me being a beginner in programming cannot really understand advanced instructions. When this code is compiled the following error is produced
main.cpp: In function 'int main()':
main.cpp:11:2: error: 'thread' was not declared in this scope
main.cpp:11:9: error: expected ';' before 'first'
main.cpp:12:9: error: expected ';' before 'second'
main.cpp:14:2: error: 'first' was not declared in this scope
main.cpp:15:2: error: 'second' was not declared in this scope
I have already included -std=c++11 in the c++ compiler additional command-line options in the project option of the Dev C++ but i can't still remove the errors. Can you please check what i am doing wrong? also as much as possible i dont want to start using other libraries as i am having a hard time building them(ex. boost)
The problem is most likely due to lack of support for C++11's std::thread in the build of GCC 4.7.1 included with TDM-GCC. Have a look at this question, for details. Your code compiles fine with GCC 4.8.1 (although it still has runtime errors):
http://ideone.com/oUhvi3
I would therefore suggest that to resolve your problem, you try updating to a more recent version of the compiler. According to this link and this link doing so should be a simple matter of installing the most recent version of the compiler into the folder where it currently resides, or alternatively, installing it in a new folder and updating the settings in Dev C++ to point to the new compiler.
However, since you are new to C++ (and programming in general), and therefore have no particular attachment to Dev C++, I would recommend that you instead switch to a more modern and widely used IDE. MS Visual Studio is a good bet for Windows, but there are plenty of open source and cross platform IDEs available for C++. Using an IDE which is popular is recommended for beginners, as you are much more likely to find sources of help and support online, and more likely to get answers on sites such as Stackoverflow, when you get stuck. There are tons of Stackoverflow questions relating to IDEs. Examples (from a quick Google search):
What is the good cross platform C++ IDE?
Best C++ IDE or Editor for Windows
https://stackoverflow.com/questions/535369/what-is-the-best-free-windows-c-ide-compiler
I encounter this error when I am trying to compile a c++ code via a Makefile.
error: expected initializer before ':' token
I have checked the compatibility of the compiler of my system
I also checked the paths etc. I also did some test; such as adding a semicolon after the 2nd declaration of class but didnt work. I have little to no experience with c++, the script is not even written by me; it is part of vtk library (Visualisation toolkit). Part of the script from where
the error generates is:
#ifndef __vtkProcessObject_h
#define __vtkProcessObject_h
#include "vtkAlgorithm.h"
class vtkDataObject;
class VTK_FILTERING_EXPORT vtkProcessObject : public vtkAlgorithm
{
public:
vtkTypeRevisionMacro(vtkProcessObject,vtkAlgorithm);
void PrintSelf(ostream& os, vtkIndent indent);
I get the error in line 8.
Probably it is something really straightforward, but as I said I have no clue how this language works.
The VTK_FILTERING_EXPORT macro is defined in a header, and is largely there for Windows and/or GCC symbol visibility. You don't mention what version of VTK you are compiling, but using CMake to generate the Makefiles would ensure the correct include paths are set up. If this is Linux, and the GCC visibility functionality has not been activated you could define the macro to nothing, but I suspect you would hit many other issues once you got past this point in the compilation.