I am trying to eliminate the warnings in my project so I can turn on the flag that treats warnings as errors. The project uses the boost library, specifically the Concept_check.hpp and cuthill_mckee_ordering.hpp files. The warnings 4510 and 4610 are shown in the concept_check.hpp file and I have tried to disable them using #pragma warning push and pop. The warnings are caused by the boost library trying to instantiate a class using the template found in concept_check.cpp when there is no constructor written for it.
My Question is this: Is there a more sure fire way that I can disable these warnings without modifying the boost code? I am using Visual studio 2010.
Perhaps you are looking in the wrong direction. As Alan Stokes pointed out, the warning is there for a reason. I have three hints that are perhaps not the answers you expect, but may bring an acceptable solution:
Instead of silencing the warning, just fix the error. I don't know your code, but there are other people that had a similar problem which was possible to fix by just declaring a variable.
Another question is: why do you want to turn all your warnings into errors? Is it really neccessary? I agree that normal code should always compile without warnings. But these warnings are not originating from your own code. Consider a static code-checker that warns you about issues where your compiler is blind about.
If you have to use -WX, move the offending code into a static object/library/module so you will be bothered about the warning only when you need to recompile this module. You could use specific compile options for this module, to get the warnings completely out of your way.
There is another possibility, but I'm not able to check whether it really works. According the Microsoft Documentation it is possible to set the warning level of specific warnings. (there are similar options for GCC). First, switch all warnings to error:
/WX
Then, set the warning level of the two offending warnings to zero:
/W04510 /W04610
A complete commandline would look like this:
cl source.cpp /WX /W04510 /W04610
The best solution would be to combine this with hint 3 above. This way, the specific compiler options are only used for the files that cause the warnings.
Maybe these solutions work.
You can disable specific warning from a .h file (#pragma warning( disable: ... ).
Related
According to cppreference [[deprecated("message string")]] we should be able to use the symbol but in VS results in error instead.
For example I wan't to issue a warning for ANSI methods in UNICODE builds and vice versa:
#ifdef UNICODE
[[deprecated("This method does not work well in UNICODE builds")]]
#endif // UNICODE
void f() {}
compiler doesn't let me compile, but standard says the attribute should allow usage but issue a warning message.
How to resolve this?, btw. my project is set to maximum conformance with the standard.
What ever the reason for VS going against the standard, is there a better way to issue a warning for above case?
Very much late to the party, but this cost me a couple of hours this morning.
By default, Visual Studio and the sdl (Security Development Lifecycle) compile flag treat
[[deprecated]] as an error. Whether or not you agree with this or not, that's how they do it.
To fix this go to Configuration Properties -> C/C++ -> Command Line and add /sdl /w34996
The /wX part represents the severity of the warning, and the rest is the error you want to report as a warning.
I hope this saves people some time.
I was able to get the compiler to treat [[deprecated]] as a warning by adding
/w34996
to the compiler options, as suggested in the responses in following link
https://developercommunity.visualstudio.com/content/problem/786502/cant-treat-deprecated-warning-as-warning-with-wx.html
is there a better way to issue a warning for above case?
There's no other way of warning about usage of a function than deprecation attribute in standard C++ at least that I know of.
Msvc has other alternatives such as #pragma deprecated(f), but those are not better.
How to resolve this?
Assuming you haven't configured your compiler to treat warnings as errors, you could proceed with writing a bug report to the maintainers.
I haven't tested it with Visual Studio, but in my case the following helped and probably is more generic:
On that error usually warnings are treated as errors with the compiler flag -Werror, that is automatically set in Visual Studio. That is the reason way a class or function marked with [[deprecated]] results in an error. To avoid explicitly that error and output it just as a warning, the compiler flag -Werror -Wno-error=deprecated-declarations can be set. In CMake it would look like:
add_compile_options(-Werror -Wno-error=deprecated-declarations)
At a company I used to work at, the build system was set up to turn warnings into errors only within changed code. It worked by supplying generating a diff (typically between the branch you were trying to merge and master and then supplying that diff to some compilation tool, and the tool would produce warnings only within the supplied diff.
This was great as it allowed you to e.g. deprecate some function, and have the build system prevent people from introducing new uses of that function, and then remove old usages of that function later.
Unfortunately, I didn't look at the setup closely enough before I left the company, and don't know how to replicate it. My question: How can I replicate this setup?
Question is tagged Clang but I would also be interested in answers that use tooling from other compilers.
If I had to implement that, my first idea would be:
Get merged file.
Analyze diff to figure out which regions were changed.
Generate a new file and inject #pragma directives1 that locally enable/disable warnings around the changed regions.
Also inject #line directives to make it look like warnings/errors are coming from the original file.
Compile modified file and save compiler warnings/errors.
Delete modified file.
Present compiler diagnostics to the user.
1 E.g. https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Pragmas.html#Diagnostic-Pragmas for GCC.
Clang supports GCC's #pragma diagnostic.
For example:
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wuninitialized"
// ... changed code here ...
#pragma GCC diagnostic pop
MSVC also has something similar:
#pragma warning(push, 3)
// ... changed code here ...
#pragma warning(pop)
I can get rid of the warnings in the build log by adding -std=c++0x to "other c++ flags", but they still show up in the side pane. I'm guessing that the other flags are not being passed to clang or whatever is responsible for parsing code for the gui...
Any ideas?
Update:
The warnings have mostly disappeared, but I'm not sure why. And every time I think they're gone, I get a few again. I suspect that forcing a build of every project in the workspace has some effect, but I'm really at a loss.
In any case, modifying "other c++ flags" does seem to affect the GUI warnings, contrary to my assumption when I asked this question. But it takes time. Ahh, Xcode.
Use a pragma instead of a command line switch, as described in the answer to "Is there a way to suppress warnings in Xcode?"
When using the std::map with types that use trivial, non-throwing, copy constructors, a compiler warning/error is thrown (warning level 4, release mode) for unreachable code in xtree. This is because the std::map has a try-catch in it that helps maintain the state of the tree in the case of an exception, but the compiler figures out that the catch statement will never be called if the stored elements don't throw. These warnings can be easily suppressed with the following lines at the top of the .cpp file:
#pragma warning(push)
#pragma warning(disable:4702)
#include <xtree>
#pragma warning(pop)
Is there a way to bypass this warning/error without changing the warning level, building in debug, suppressing the warning, or using a different type in the map? Is there plans to change this in the standard library?
Update:
Maybe it is compiler specific. I am using vc7.
The error is below:
c:\program files\microsoft visual studio .net 2003\vc7\include\xtree(1116) : error C2220: warning treated as error - no 'object' file generated
c:\program files\microsoft visual studio .net 2003\vc7\include\xtree(1116) : warning C4702: unreachable code
Apparently the xtree is used by the std::map.
Unfortunately it looks like xtree is part of the underlying implementation of map in VC7, and as such there isn't much that can be done to mitigate it. It looks like it's a bug in the standard library.
Is it a possibility to use a newer compiler? I'm fairly sure there are free downloads of more recent versions of the compiler you could use, and perhaps they've fixed this issue.
If that's not an option, probably the best solution is to wrap the include of map into your own private header, complete with a comment and the #pragma+include <xtree> lines you already discovered (in addition to an include of map. This way you hide the workaround from normal use.
I can inhibit many warnings in Visual Studio 2005 SP1 in the C/C++ Advanced property page, which causes the IDE to use the /wd switch on the command line which invokes the compiler. However, when I try to inhibit warning 4200 (nonstandard extension used : zero-sized array in struct/union), it still appears when I compile. (Of course it's justified; I'm just not in a position to fix the code, nor would it be worth bothering, because it's generated, and the warning is entirely benign under the circumstances.) Does anybody happen to know if this is a bug in the compiler? Or might there be something I can do about it?
To completely disable the warning in the file you can add the following to the top of the file
#pragma warning(disable:2400)
If you want some more flexibility other than a blanket disable for the file, the following page lists several other more fine grained options.
http://msdn.microsoft.com/en-us/library/2c8f766e(VS.80).aspx
It's unclear based on your information as to whether or not it's a bug in the compiler or a configuration issue. I would lean towards a configuration issue, specifically conflicting compiler options that is making it difficult to suppress the warning.
EDIT
OP mentioned they can't control the generated code so they can't directly include the pragma. If that's the case then try this trick. Say the file name is Generated.cpp. No longer include Generated.cpp as one of the files to compile. Instead create a new file called Example.cpp with the following contents
#pragma warning(disable:2400)
#include "Generated.cpp"
Now you'll get the text of Generated.cpp with the disabled warning by only compiling Example.cpp.
You mean like with pragma?
#pragma warning( disable : 2400 )