vs report a error such as:
can not find xxx.lib
How do I check out why vs need to link xxx.lib? Is there a trace log? My project have not use boost.regex, but vs report a error says can not find regex.lib. So I want to find out which part of code refer to regex
LNK error: LIBCMT.lib: xxx was already defined in LIBCMTD.lib
How do I check why vs also link yyy.lib even this is a debug build? I have 2 projects, they link to same libs, all libs and project itself was /MTd. But one of them will report above error, I think it shouldn't link LIBCMT.lib because it is a release version lib, and another project is OK so the lib file was build correctly
VS can show the link trace?
1) Let's start with how the linker actually knows what to link with. Basically there are 2 categories:
Libraries specified in the project settings in the linker options as additional inputs
Libraries added in code with precompiler directive #pragma comment (generally the same thing as above but people have different tastes)
Otherwise you just get information about missing symbols but not the actual library they are from. What you can do to help is under visual studio linker options set Show Progress to For Libraries Searched (or just /VERBOSE:LIB linker flag), that will actually show you what dependencies are added after each lib is loaded, this also helps with point 2) to see which library loads which run-time.
2) Already mentioned in 1) that you can make the linker show library load progress, otherwise if a dynamic C run-time is used in the external library you are linking against you could use Dependency Walker to examine the dependencies of the library and find if the C run-time dll that is needed is debug or release by 'd' suffix in the dll name. If the library is already linked with static run-time then I guess only the linker errors will warn you. But I think that most serious libraries are correctly packed and structured so that you will be able to tell which files contain the debug version and which the release. If the library has only release version, well than that's another story. But i mean still, you can reconfigure the Debug configuration of your project to actually link against the release run-time to satisfy the external library, of course this prevents some debugging features, debug heap, etc.
For the missing boost regex library problem, I think the cause is due to boost's default autolink behaviour. If you include one of the headers of some of the boost libraries (not all of them, but regex is one of them), then these will cause Visual Studio to automatically link against the library. It uses a special pragma of the form:
#pragma comment(lib, "regex")
This has the effect of automatically adding a flag to the linker command. However, it's only picked up during compilation and so you won't see it in the project properties. In the case of boost, the solution to this is quite simple - find boost/config/user.hpp and uncomment the line
#define BOOST_ALL_NO_LIB
This will turn off the autolink behaviour for all libraries. Alternatively you can use #define BOOST_REGEX_NO_LIB to change this just for the regex library.
To solve the second problem, you need to find out which library is linking against the release build. Try selecting all projects in the solution and open Properties -> C++ -> Code Generation. You will probably find that the Runtime Library setting will be blank (because the option is different for some of the libraries. Force it to the correct threaded/single-threaded Debug option and rebuild.
Related
I'm working on a DLL project in Visual Studio 2017. This library adds some functionality around the ftd2xx library from FTDI. I set up the project as described in this instruction. I'm linking against the static version of the ft2dxx library. The only difference between the instruction and my project is the selection of the Runtime Library. The instruction states (figure 2.16) that the Multi-threaded Debug Runtime library must be used. In my case, I selected the Multi-threaded Debug DLL (/MDd) option, because i'm working on an DLL (see the image below)
When i build the project, I get the following errors:
When i clicked on the first warning, this page opens. I changed the project properties as described on the webpage:
This fixes the first warning, but the link errors still exists:
So, to conclude: I assume there is something wrong with the Runtime Library, used by the ftd2xx library, but I have no idea how to fix this. Any suggestions?
I found the solution here. The solution is to add the 'legacy_stdio_definitions.lib' to the linker input. To do this, go to the project properties -> Linker -> Input and add 'legacy_stdio_definitions.lib' to the additional dependencies.
I am trying to create a C++ project in Visual Studio 2013 that has CGAL and Boost (and a couple of other libraries) as dependencies. I preferably like to link to these libraries dynamically. Also, I'd like to link to the "Release" versions of these libraries for performance reasons (not the "Debug" versions).
Starting from an empty C++ project, I added the path to header files of the aforementioned libraries as shown in the image below:
Inside the linker options, I then added the directories that contain the DLL and lib files of the external libraries. (CGAL directory contains CGAL's compiled DLL files along with lib files).
At this point, I have not added a single "lib" file "Additional Dependencies" dialog:
Now something weird is going on and I cannot explain why. If I try to build the project as-is (under the "Debug" configuration), I get a LNK1104 error about the linker not being able to find CGAL-vc120-mt-gd-4.7.lib. I know that the error means I should add the lib file in "Additional Dependencies" dialog...
But wait... WHAT...?!!
How does Visual Studio know how to automatically link against this lib file?! Worse yet, how does it know it needs the "debug" version of the library? (With the gd suffix). Also, how does it know I compiled CGAL with VS2013!!??
At first, I though the project was inheriting properties from some preset property sheets somewhere in my system. But I am certain that's not the case as this behavior shows even with a project created from scratch.
My main question is, how would you force Visual Studio to link against the "Release" version of this library? (eg. CGAL-vc120-mt-4.7.lib)
Side question but related: Am I even linking against the DLL files? How can I be certain that I am in deed doing dynamic linking and not static linking?
This is probably happening due to the #pragma comment(lib) mechanism - eg see What does "#pragma comment" mean?
This is a way of the compiler emitting instructions for the linker so that it can decide between multiple versions of a library depending on the compiler version. In this case it means that it can automatically pick up the correct version of the library (debug vs release, vs2013 vs vs2015, MT vs MD, etc). When you added the explicit reference to the library in Additional Dependencies then it is now trying to look for two files.
So, to fix the problem, remove it from Additional Dependencies and let VS pick the right library. If you are getting the LNK1104 error then it suggests that either the link library path isn't set up correctly, or you don't have the CGAL library file it's looking for. You can increase the verbosity settings for the linker in the Project Options to get more detail about what's happening.
We have a large project using VS2008 and boost 1_42. I'm trying to upgrade to VS2010 and boost 1_44. I installed VS2010 and boost 1_44 and converted the project. Now I am trying to build, and everything compiles, but fails when linking:
LINK : fatal error LNK1104: cannot open file 'libboost_thread-vc90-mt-1_42.lib'
I have changed the include and lib directories to point to the new boost 1_44 files and I have renamed the old boost 1_42 directory.
Why is the linker still looking for a vc90-1_42 file, when it is only using 1_44 headers? Is there a way that I can determine WHY the linker wants this file? The linker obviously thinks it needs the file, but why?
I have cleaned the project and I am re-building to ensure any old build files are erased.
I've run into exactly this problem a couple of times too. It's usually been some old temporary files but like in your case cleaning didn't always do the trick straight away. Does your project include any static libs that might have been built with 1.42?
Something you can try which may or may not be helpful in tracking down your issue:
Rename the old boost directory back to it's original name
Clean the solution
Under C/C++->Command Line->Additional Options add "/showIncludes"
Under Linker->Command Line->Additional Options add "/verbose:lib"
Rebuild all
Then when you build you'll be able to see at which point 1.42 headers are included, etc. in the output window. Somehow doing this helped me in tracking down where the problem was.
Along with changing the lib directory, you need to change the name of the boost library. That's in the Linker | Input section of the project settings.
Your added comment makes it clear that the dependency on the Boost 1.42 library was being created indirectly by another library that hadn't been rebuilt.
For this you basically have two choices: either add that library as a project to your main solution, and make sure it has enough dependency information that it'll be re-built when you upgrade Boost, or use the /Zl compiler switch when you build your library. This tells the compiler you're building a library so you do not want to embed library dependencies like this.
Boost uses
#pragma comment(lib)
command to inform the linker of libraries it needs to link with. It is not an error. If Boost says you need it, it's likely you do.
On How can I find out why the linker wants this file?
There are programs which will go through your app and dlls/libs and report the content of manifests and what the binaries report they depend on. You could then scan the report for the unexpected libraries being included. We used this mainly to find libs including the previous version of the VC runtime.
Have not used the one we had in about 5 years though, now if only I could remember the name of the app!
DependancyWalker (depends.exe) will allow you to see dependancies of dll/exe but not static libs.
You could open each binary as a 'file' in MSVS and look at the manifest content by hand, but I imaging this would be a bit painful. I've not tried this with a static lib.
I have a template VS .NET 2003 project, which colleagues copy and customise when developing their software.
It appears the template was altered a while back to set the IgnoreSpecificLibrary property to have libcmt.lib for both release and debug builds (i.e. for both release and debug, the build should ignore libcmt.lib in the linker).
Some projects based on this have since been built, with the release build pulling in libcmtd.lib (evident by looking through the project .map file) which appears to have caused some runtime issues (i.e. a dialog window being flashed up as though a breakpoint had been set).
Does setting IgnoreSpecificLibrary to exclude libcmt.lib automatically make the project link against libcmtd.lib?
What is weird is that building the template (with the incorrect setting) links against libcmt.lib whereas some of the customised projects (though not all) link against libcmtd.lib.
Any ideas?
This is what happened:
After compiling the linker takes your object-files and create among others
a symbol table ,which has symol-request that have not been fullfilled.
Then the linker goes through your list of libraries trying resolve those
unfullfilled symbols. Since you ignore libcmt.lib ,your third-party library
has left or added some unresolved symbols and it contains a linker request
to resolve those from licmtd.lib (and maybe other libs as well) ,since it
was compilled with debug option.
If you hadn't ignored libcmt.lib those symbols would most likely be resolved
by libcmt.lib and there was no need to pull in stuff from libcmtd.lib (even though
it would be looked at to resolve other symbols that were still unfullfilled)
You may try to igmore libcmtd.lib also. If you now get unresolvd externals then
it was probebly no a good idea to ignore libcmt.dll.
Many projects ignore the libcmt.lib, because it conflicts with the dynamic version msvcrt.lib.
Ignoring libcmt in the linker make the project compile with msvcrt.lib
How do you specify, in Visual Studio 2010, the order in which library files should be linked?
I have a project that links against libexpat and against another library. This library (not under my control) seems to also include libexpat. The problem is that 'we' use a different version of the library (XML_UNICODE vs not). In Visual Studio 2008 things seemed to work out okay (might have been a coincidence), but in Visual Studio 2010 the wrong instance of libexpat is linked. I was thinking that if I could specify the order in which these two libraries should be linked that then I could circumvent the problem.
A few years back I discovered a hack that allows you to force Visual C++ to link libraries with a specific precedence. This is not elegant, but it is functional.
It seems that the linker for Visual C++ generates link order on the fly based on symbol dependencies. By adding a symbol reference up-front, you can force the linker to include the first library specified in the linker input. Please note, I have only tested this with Visual C++ 6 and 8 (2005).
Let's say for example that you have two libraries with the symbol XML_ParserCreate:
libexpat.lib - XML_ParserCreate
someother.lib - OtherSymbolsYouNeed, XML_ParserCreate
First, order your library dependencies as you would expect, libexpat.lib and then someother.lib. Via command line these would be options to link.exe. In Visual Studio 2005, they would be options under the project's Configuration Properties -> Linker -> Input -> Additional Dependencies. I would imagine Visual C++ 2010 has a similar menu.
Next, add a command line option that defines a known repeated symbol up-front, by using the /INCLUDE linker option. In Visual Studio 2005, this can be added under the project's Configuration Properties -> Linker -> Command Line -> Additional options:
/out some.exe ... libexpat.lib someother.lib
/include:XML_ParserCreate
The definition of this symbol will cause the linker to immediately prefer the first library that terminates (realizes) it. In general Visual C++ will generate an error with repeated symbols; if you haven't already, make sure you are also specifying the /FORCE:MULTIPLE linker option.
My specific need for this was using the DUMA memory debugging library. It defines a variety of memory functions that are also defined in libcmtd.lib. The following would incorrectly link libcmtd's version of _malloc, despite a library order that seems to the contrary:
/out some.exe ... duma.lib libcmtd.lib
/FORCE:MULTIPLE
This was resolved by manually adding the symbol, and has worked reliably for years:
/out some.exe ... duma.lib libcmtd.lib
/INCLUDE:_malloc /FORCE:MULTIPLE
I have found 'a' solution: if you add the libraries through #pragma comment(lib... the order of linking is the same as the order in which you type those pragma's. I'm still keeping the question open for a solution when the libraries are added through the project file instead of through pragma statements.
You could create a DLL with the third party library and link it against the static version of expat that it needs and then link your code against the version of expat you need.
However, the fact that it worked before might mean that one library has all the functionality of the other plus some extra. I don't know the details of expat. If that is the case, you need to make sure that you only have the version you want to use in your library search path. A different search directory order in the other version of the compiler could explain the change in behaviour.
I think you can change the order in which library files are linked bij adding them in the project file in linker -> input -> additional dependencies. The library files will be linked in the order in which they are specified.