hi i have compiled the below specified code
long (*interlocked_increment) (volatile long *);
long InterlockedIncrement(volatile long & value) const {
return interlocked_increment(&value);
}
static long m_interlocked_increment(volatile long * pv) {
#ifdef WIN32
return InterlockedIncrement(pv);
#elif defined(HAS_SYNC_FUNCTIONS)
return __sync_fetch_and_add(pv, 1L);
#else
return ++(*pv);
#endif
}
in g++ compiler it will works fine. but while i try the same in visual c++ 2008 it shows the below specified error.ho can i resolve this problem.
Error 5 error C3861: 'InterlockedIncrement': identifier not found
The InterlockedIncrement() function takes volatile long &, whereas you're passing it a volatile long *, thus the compiler can't find the corresponding function signature.
Related
I am trying to compile some library code and ran into an error; I simplified the example and I have the following MVCE which fails to compile with MSVC 2019 with the error
error C2440: 'return': cannot convert from 'const char *' to 'const char (&)[20]'
static constexpr const char somethingWeird[] = "Well, that's odd...";
void fail() { throw 0; }
// This doesn't work
constexpr const char(&checkNullTerminatedGood(const char(&a)[20]))[20]{
return a[19] == char(0) ? decltype(a)(a) : (fail(), decltype(a)(a));
}
static constexpr const auto somethingElseNew = checkNullTerminatedGood(somethingWeird);
When I convert the ternary operator to a proper if-statement, the code compiles well:
static constexpr const char somethingWeird[] = "Well, that's odd...";
void fail() { throw 0; }
// This works
constexpr const char(&checkNullTerminatedGood(const char(&a)[20]))[20]{
if (a[19] == char(0)) {
return decltype(a)(a);
} else {
return (fail(), decltype(a)(a));
}
}
static constexpr const auto somethingElseNew = checkNullTerminatedGood(somethingWeird);
Is this a bug in MSVC? The first snippet compiles with GCC and Clang.
A bit of googling shows this is know problem which is claimed to be fixed (but it is not).
C++ Overly aggressive decay of static array to pointer in ternary operator - Developer Community
Solution
by Leo Zhang [MSFT] Sep 07, 2017 at 02:35 AM
Thank you for your feedback! This issue has been fixed and it will be available in the next update to Visual Studio 2017. Thank you for helping us build a better Visual Studio!”
I'm using Libtooling to parse Windows SDK headers but there is a problem in getting functions calling conventions, The libtooling always return __cdell for WINAPI or __stdcall calling convention which is the defualt calling convention of Win32 API's.
This is an input example
VOID
__stdcall
TestFunction (_In_ BOOLEAN is_valid);
This is my Function Visitor function of my RecursiveASTVisitor
virtual bool VisitFunctionDecl(clang::FunctionDecl *func)
{
// ...
if (m_AstContext->getSourceManager().isInMainFile(func->getLocation()))
{
if (func->hasAttrs())
{
auto stdcall = func->hasAttr<StdCallAttr>(); // always return False
}
const clang::FunctionProtoType * prototype = func->getType()->getAs<FunctionProtoType>();
if (prototype)
{
auto stdcall = prototype->hasAttr(attr::Kind::StdCall); // always return False
errs() << clang::FunctionType::getNameForCallConv(prototype->getCallConv()).str() << " "; // always return cdecl
}
func->dumpColor(); // But there is __attribute__((stdcall)) in dumped output!
}
// ...
}
And finally output of func->dumpColor(); for input example!
^
FunctionDecl 0x218c95bb6f0 <C:\Program Files (x86)\Windows Kits\10\Include\10.0.17134.0\um\winnt.h:430:14, C:\ExampleInput.h:18:36> col:1 TestFunction 'void (BOOLEAN) __attribute__((stdcall))':'void (BOOLEAN)'
`-ParmVarDecl 0x218c95bb5c0 <col:20, col:28> col:28 is_valid 'BOOLEAN':'unsigned char'
I ran it with/without this options too, for compatibility reasons but no difference at all :-(
-fms-compatibility
-fms-extensions
-fms-compatibility-version=19
Any idea?
Update
I found the problem, It's because of defualt compile config of #Clang. It's 64-bit (in 64-bit toolchain), And it doesn't work with __stdcall in 64-bit mode
If I use the 32-bit version (or -m32 option) then it will works correctly
Any idea why it happens in 64-bit mode?
I am running into a couple of errors related to "htonf" c++ function error while compiling my code. Help will be much appreciated.
Following are the errors:
Error C2556 'long htonf(float)': overloaded function differs only by return type from 'unsigned int htonf(float)'
Error C2371 'htonf': redefinition; different basic types ecueHost
Error C2065 'htonf': undeclared identifier
The error is appearing in the datapacket.cpp below
#include "str.h"
#include "DataPacket.h"
#include "exception.h"
#include "message.h"
#include "object.h"
#include "util.h"
#define MAX_DATA_LENGTH 4096
long htonf(float f)
{
long x;
x = *((long*)&f);
x = htonl(x);
return x;
}
float ntohf(long l)
{
float f;
l = ntohl(l);
f = *((float*)&l);
return f;
}
In the "winsock2.h" header file included in "datapacket.h" header, the "htonf" is defined as under:
#ifndef htonf
__inline unsigned __int32 htonf ( float Value )
{
unsigned __int32 Tempval;
unsigned __int32 Retval;
Tempval = *(unsigned __int32*)(&Value);
Retval = _WS2_32_WINSOCK_SWAP_LONG
(Tempval);
return Retval;
}
#endif /* htonf */
and in the "datapacket.cpp" file itself the "htonf" is also declared here
// Store a float to the datapacket
TDataPacket& TDataPacket::operator<<(float f)
{
long x = htonf(f);
return SerializingIn(&x, LONG_SIZE);
}
Error C2556 'long htonf(float)': overloaded function differs only by return type from 'unsigned int htonf(float)'
This error message explains it completely.
You have:
__inline unsigned __int32 htonf ( float Value )
in winsock2.h, and
long htonf(float f)
in datapacket.cpp. Your easiest solution will be to change the definition of htonf() in datapacket.cpp to match what you have in winsock2.h, and adjust the implementation as needed to reflect the new return type.
First of all, long is signed while unsigned __int32 is unsigned, and secondly, even though they are the same size under MSVC, __int32 and long are not interchangeable data types.
I've built a VRPN client on Linux. It's based on this: http://www.vrgeeks.org/vrpn/tutorial---use-vrpn
Here's some of the code:
vrpn_Analog_Remote * analog = NULL;
vrpn_Button_Remote * button = NULL;
vrpn_Tracker_Remote * tracker = NULL;
// Things happen...
analog = new vrpn_Analog_Remote("pathToAnalog");
analog->register_change_handler(NULL, handleAnalog);
button = new vrpn_Button_Remote("pathToButton");
button->register_change_handler(NULL, handleButton);
tracker = new vrpn_Tracker_Remote("pathToTracker");
tracker->register_change_handler(NULL, handleTracker);
Here are the callbacks refered to in this code:
void handleAnalog(void * userData, const vrpn_ANALOGCB a) {
// Do stuff...
}
void handleButton(void * userData, const vrpn_BUTTONCB b) {
// Do stuff...
}
void handleTracker(void * userData, const vrpn_TRACKERCB t) {
// Do stuff...
}
And here is where all of these references to VRPN are defined:
https://github.com/vrpn/vrpn/blob/master/vrpn_Analog.h#L168
https://github.com/vrpn/vrpn/blob/master/vrpn_Button.h#L225
https://github.com/vrpn/vrpn/blob/master/vrpn_Tracker.h#L284
These compile without even a warning on Linux and can actually be used. Everything worked as expected. All the types here seem to satisfy the compiler, g++.
But on Windows, whether I use Visual Studio 2015 or MinGW's g++, I get this for the first two callback registrations:
invalid conversion from 'void (*)(void*, vrpn_ANALOGCB) {aka void (*)(void*, _vrpn_ANALOGCB)}' to 'vrpn_ANALOGCHANGEHANDLER {aka
void (__attribute__((__stdcall__)) *)(void*, _vrpn_ANALOGCB)}' [-fpermissive]
invalid conversion from 'void (*)(void*, vrpn_BUTTONCB) {aka void (*)(void*, _vrpn_BUTTONCB)}' to 'vrpn_BUTTONCHANGEHANDLER {aka
void (__attribute__((__stdcall__)) *)(void*, _vrpn_BUTTONCB)}' [-fpermissive]
And for the last one, I get a different error:
call of overloaded 'register_change_handler(NULL, void (&)(void*, vrpn_TRACKERCB))' is
ambiguous
Now that I'm typing this, I'm thinking maybe VRPN was compiled differently on Windows and that's why the compiler now has a problem with my code. But I'm very lost as to what to do.
Try declaring your callbacks like this:
void VRPN_CALLBACK handleAnalog(void * userData, const vrpn_ANALOGCB a) {
// Do stuff...
}
For linux, the VRPN_CALLBACK define is empty, so you did not notice any problems there. For windows, the VRPN library devs decided that they expect a callback that adheres to the __stdcall calling-convention. Thus you have to declare your function accordingly, and the most painless+portable way is to use the very same VRPN_CALLBACK define that they provide.
Clues to this came from your links to the code at github:
[vrpn_Analog.h]
typedef void(VRPN_CALLBACK *vrpn_ANALOGCHANGEHANDLER)(void *userdata,
const vrpn_ANALOGCB info);
and the callback define is made here:
[vrpn_Configure.h]
#ifdef _WIN32 // [ ...
#define VRPN_CALLBACK __stdcall
#else // ... ] WIN32 [
#define VRPN_CALLBACK
#endif // ] not WIN32
Calling system() to run an external .exe and checking error code upon errors:
#include <errno.h>
#include <stdlib.h>
function()
{
errno_t err;
if( system(tailCmd) == -1) //if there is an error get errno
{
//Error calling tail.exe
_get_errno( &err );
}
}
First two compile errors:
error C2065: 'err' : undeclared identifier
error C2065: 'errno_t' : undeclared identifier
Not sure why as I am including the required and optional header files?
Any help is appreciated. Thank You.
A typical usage is like:
if (somecall() == -1) {
int errsv = errno;
printf("somecall() failed\n");
if (errsv == ...) { ... }
}
which is taken from here.
Just use 'errno' without any declaration. It is a macro that expands to an int value.
In the world of Standard C, the type 'errno_t' is defined by TR24731-1 (see Do you use the TR 24731 'safe' functions? for more information) and you have to 'activate it' by defining '__STDC_WANT_LIB_EXT1__'.
However, you appear to be working on Windows (judging from 'tail.exe', and also the non-standard '_get_errno()'). The rules there may depend on the C compiler you are using.
You should be able to chase down the information from this MSDN article on 'Security Enhancements in the CRT'. My impression was that it should be defined unless you actively suppress the feature, so check out whether you are actively suppressing it in your compilations.
Be aware that the MSVC definition of functions such as vsnprintf_s() do not match the TR24731-1 definitions:
MSDN:
int vsnprintf_s(
char *buffer,
size_t sizeOfBuffer,
size_t count,
const char *format,
va_list argptr
);
TR 24731-1:
int vsnprintf_s(
char * restrict s,
rsize_t n,
const char * restrict format,
va_list arg
);
The difference is not just a question of type aliases or qualifiers (rsize_t, restrict) - there are two sizes in the MS version and one in the Standard version. So much for standardization!