I am doing the migration of standard library in my Android projects from gnustl (libstdc++) to llvm-libc++.
and in one of the project, I am getting multiple errors of the missing header file,
fatal error: 'hashtable.h' file not found
#include "hashtable.h"
^~~~~~~~~~~~~
clang++.exe: error: clang frontend command failed due to signal (use -v to see invocation)
Android clang version 5.0.300080 (based on LLVM 5.0.300080)
Preprocessed file output revealed that this file is supplied by gnustl
.. f:/nugetcache/androidndk.16.1.1/sources/cxx-stl/gnu-libstdc++/4.9/include/backward\\hashtable.h
But after I have migrated to libc++ I could not find the equivalent header in libc++. This header file declares class HashTable
template<class _Val, class _Key, class _HashFcn,
class _ExtractKey, class _EqualKey, class _Alloc>
class hashtable
{...}
I tried searching for this header and this class in libc++ code but could not find anything. I think this is an important class and must be provided by libc++ in some form but I could not identify it.
Has anyone faced error due to this discrepancy and what is the suggested work-around?
I tried searching for this header and this class in libc++ code but could not find anything. I think this is an important class and must be provided by libc++ in some form but I could not identify it.
This is a libstdc++ extension, left over from pre-C++11 days.
If you take a look at the contents here, you'll see that it has a comment at the top says: This is an internal header file, included by other library headers. Do not attempt to use it directly.
libc++ does not contain that header file and contains more specific interfaces for different classes of maps.
Hence #marshall was right in pointing that out, having said that we don't need that header at all.
Related
I'm trying to compile a Windows DLL for code originally intended for a Unix platform. One problem I have is that Windows fopen() defaults to O_TEXT, but Unix defaults to O_BINARY.
Windows recommends two ways to solve this:
Use _set_fmode() function, didn't work for me probably because I could not call it from correct context.
Link with binmode.obj object file. This file is included with the compiler, and the compiler knows where to look for it.
The latter worked for my own code, but it does not seem to work for third party static libraries. Looking at the linker output, I can see that static libraries are included before binmode.obj, but binmode.obj was included before my own object files.
The real solution should be to persuade all external libraries to include binmode.obj, but this is somewhat non-trivial and might incur significant maintenance overhead in the future.
So I'd like to try to move the binmode.obj to the beginning of the linker command line, but this proved to be surprisingly difficult. I've tried:
target_link_libraries( mylib PRIVATE binmode.obj ) - Got correct position, but got renamed to binmode.obj.lib casuing linker error.
Tried making a static library with binmode.obj as a pre-compiled object, but got an error that the file has a relative path. I have no idea how to make it a full path.
Tried adding it as a linker flag in different ways, even including using toolchain file, but it all ended up with binmode.obj being placed after libraries.
I'm now out of ideas and feel I need help with this. Any suggestions how to fix this?
#fabian's comment made me read the right part of CMake documentation, which made me realize that UNKNOWN library type could be used. Using the following code in CMake I could make binmode.obj appear before all libraries:
add_library( binmode_obj UNKNOWN IMPORTED GLOBAL )
set_target_properties( binmode_obj PROPERTIES IMPORTED_LOCATION binmode.obj )
target_link_libraries( mylib PUBLIC binmode_obj )
This solved my problem of trying out if link binmode.obj before libraries might fix my original problem. It didn't, unfortunately. But that is another problem...
I'm getting a linker error indicating that the linker was unable to open a file (a static library) and therefore it fails. I am having a very difficult time troubleshooting this error because I never told the linker to link to the file which it is failing to open.
I am telling the linker to link to several static libraries. Many of the libraries I am linking to are wxWidgets static libraries. I don't need ALL of the modules from wxWidgets, so there are some which I am linking to and many which I am not. The file which the linker can't open is 'wxbase31ud_net.lib'. Like I said, that file is not among the libraries I am linking to. My immediate thought was that this dependency was being introduced implicitly somehow, perhaps by one of the wxwidgets libraries I WAS linking to. I didn't think static linkage worked this way but I didn't have any other ideas. I have been investigating that possibility and I've found nothing which indicates that is the case.
I set the build output verbosity to maximum, and the 'wxbase31ud_net.lib' is never mentioned anywhere until the error is reported.
I confirmed in my cmake project that the file in question was never passed back to me from the FindWxWidgets module, and was never referenced in any of the lists of files I associate with the target.
I grepped through the entire project directory and found no reference to the file anywhere, including the cmake-generated project files (visual studio project files).
What could be causing the linker to try and open this file?
Edit: Also, to be clear, the error I'm seeing is LNK1104
it's probably from a #pragma comment(lib,"???") except in the case of wx the argument to the pragma may be complex macros and it will be difficult to grep. This particular one may be from setup.h with #pragma comment(lib, wxWX_LIB_NAME("base", "")). You should be solving this by adding the directory with the wx libs to the linker's search directories.
The answer by zeromus is correct, this is almost certainly indeed due to including msvc/wx/setup.h which contains #pragma comment(lib)s. Possible solutions:
Simplest: build all the libraries, this will solve the errors and it's not a problem to link with a library you don't use.
Also simple but slightly less obvious: predefine wxNO_NET_LIB when building your project, this will prevent the file above from autolinking this particular library. You may/will need to define more wxNO_XXX_LIB symbols if you're missing other libraries, of course.
Less simple but arguably the least magic too: stop using $(WXWIN)/include/msvc in your include path, then wx/setup.h under it won't be included and nothing will be linked in automatically. The drawback is that you will have to specify all the libraries you do need to link with manually.
When I call a methods that are declared and defined in the header file I get SIGSEGV!
When I call a methods that are not defined in header (they are implemented in .cpp file) everything works fine.
How linker works?How to solve this issue?
Thanks
I figure out what is problem!
In Android.mk must be included "LOCAL_CFLAGS += -DSKIA_DLL".
This will prevent instance counting. Instance counting relies on static
variables in functions defined in header files,which increase size of class and changes the application binary interface (ABI) !
I am a cmake newbie (on Debian/Sid/Linux/x86-64)
I forked libonion on https://github.com/bstarynk/onion to enable customization of malloc with Boehm's garbage collector; see this mail thread.
I added two files there onion/src/low_util.c and onion_src/low_util.h (which is #include-d successfully in several other patched files.
It is compiled but not linked.
set(SOURCES onion.c codecs.c dict.c low_util.c request.c response.c handler.c
log.c sessions.c sessions_mem.c shortcuts.c block.c mime.c url.c ${POLLER_C}
listen_point.c request_parser.c http.c ${HTTPS_C} websocket.c ${RANDOM_C} ${SQLITE3_C})
later:
SET(INCLUDES_ONION block.h codecs.h dict.h handler.h http.h https.h listen_point.h low_util.h log.h mime.h onion.h poller.h request.h response.h server.h sessions.h shortcuts.h types.h types_internal.h url.h websocket.h ${SQLITE3_H})
MESSAGE(STATUS "Found include files ${INCLUDES_ONION}")
but when I build, my file low_util.c got compiled but not linked.
Linking C executable otemplate
CMakeFiles/opack.dir/__/__/src/onion/dict.c.o: In function `onion_dict_new':
dict.c:(.text+0x1bc): undefined reference to `onionlow_calloc'
CMakeFiles/opack.dir/__/__/src/onion/dict.c.o: In function `onion_dict_node_data_free':
dict.c:(.text+0x2ec): undefined reference to `onionlow_free'
CMakeFiles/opack.dir/__/__/src/onion/dict.c.o: In function `onion_dict_node_add':
Notice that libonion is a library (in C, providing HTTP service) and that I just want to add a low_util.c file (wrapping malloc & pthread_create etc... to make Boehm's GC happy: it is calling GC_malloc and GC_pthread_create ....) with its low_util.h header. Surprisingly, they get compiled, but do not seems to be linked. And I am not familiar with cmake and I am not familiar with how D.Moreno (the main author of libonion) has organized his cmake files.
Any clues?
Apply the following patch to make it link. The two executables which are being linked with the symbols generated from the .c file you added are missing and are added in the patch.
http://pastebin.com/mDMRiUQu
Based on what you posted, its hard to tell what could be wrong. The cake source code above says that a variable ${SOURCES} is equivalent to onion.c codecs.c dict.c low_util.c ... ${SQLITE3_C}, and a variable ${INCLUDE_ONION} is equivalent to block.h codecs.h dict.h ... ${SQLITE3_H}. You did not provide any targets or the files included in those targets.
A brief list of things that may help:
where do you define the top level library or executable? If your making a library, you will need the command add_library(). If you are making an executable, you will need the add_executable() command.
Use the command target_link_libraries() to resolve dependencies. Rather than placing all of the source files in a single library, group similar together in a single target (a target is defined by the add_* commands), and use this command to link the targets after compilation.
Use the find_package() to get any libraries which are defined on your system but not in you project. Then, link to that library using the target_link_libraries() command.
In this case, if the onion_dict_* functions are defined within the same library, your not including those files in library. When you use add_library or add_executable, ensure you add those files to the list. If the functions are within your project but not in the same library, use the target_link_libraries() command to link to the library which contains the correct files. If those commands are defined in an external library, then first find the library using find_package(), and then link to the library using target_link_libraries().
I have a tlb files that contains some function declaration that I need to use.
If I use
#import "type_library.tlb"
I can correclty reference the function from my code:
tlb_namespace::required_function();
But when I compile the project the linker says that tlb_namespace::required_function is an unresolved external symbol.
How can I succesfully build this kind of project?
EDIT:
I have used the same type library in a Dummy VBA access project. I have added the reference to the type library and I have noticed that some of the function contained in the type library are correctly called. But some of them are not. VBA says It can't locate their entry point in the related dll.
Can this explain the unresolved external symbol when building c++ app?
I have also noticed that the failing function are declared in the tlb like this:
UPPER_function_name
but in the dll are declared like this:
Upper_function_name
Can this be the issue?
Is it possible to solve this kind of error directly modifying the binary tlb file or dll?
Use IDE to view TLB information.
Use this help : How to: View Type Library Information
At IDE : View-> Object Browser, click "..." Edit Custom Component Set, browse your TLB file and Add to view information.
Confirm namespace used for.
use the namespace to resolve the linker error:
example:
#import "<>" raw_interfaces_only
using namespace <>
this will resolve the problem