I'd like my Xcode project to go through a Build And Analyze step without generating any errors, warnings, or static analysis messages. A problem with this is that my project includes libraries that generate (possibly innocuous) warnings and static analysis messages.
I can't find a way to disable specific Clang warnings so that "my" code builds with zero issues. Is this possible?
I wasn't able to find any way to do this, and filed a bug against Clang. The team seems to want to add this functionality, but it's not there yet.
The bug is: http://llvm.org/bugs/show_bug.cgi?id=7296
Also, one can use a __clang_analyzer__ macro to ifdef out any code that one doesn't want Clang to process.
The Build and Analyze step is clang - thats the "analyze" part. It wouldn't make sense to analyze your code and not have clang tell you about issues it find. That's like going to a car wash and telling them not to touch the car.
From talking to the guy that wrote clang at WWDC, it is extremely unlikely that anything it identifies as an issue is actually not. If you think you have some examples of code that works fine but clang complains, please file a bugreport with example code so Apple can fix that.
You can disable some compiler warnings through the use of flags, but not all of them are an option.
Related
I have been trying to go through this tutorial and I always get stuck in the second build of GCC when making the cross-toolchain. It errors out saying that I am attempting to call a poisoned calloc. I have gone through several patches and what they all seem to do is just #include the offending system header (in this case pthread.h) earlier in the source code. Since there are no patches for my particular problem, I have gone ahead and emulated their solutions in my case. While this works (compilation now fails because I don't have some ISL files) it feels like a hack, and I suspect that the root problem is further back in the build.
Thus, I wanted to ask:
Why are symbols poisoned? Why would the GCC maintainers want some symbols not to be used?
What are the general causes for this problem? Is it really just a bug or is this a problem that arises in more general situations?
I am more interested in the generalities of this issue, but if it helps, I am using the latest release of Alpine Linux (with gcc 12.2.1) trying to compile gcc 11.2
.0 for the same target architecture as the host (x86-64).
I am trying to build the apcupsd package under a newer version of MacOS and Xcode, but the configure script supplied with the current version of apcupsd breaks under Xcode 12.4 (though it worked under Xcode 11.2).
The error is gethostbyname_r is required. Now, configure tests for this function, and ordinarily it adapts to systems that do not provide it. On the newer Xcode version, however, configure just exits with an error. I THINK it has something to do with Apple making the -Werror setting mandatory. I've found that I can get a successful build by commenting out the broken test in configure, then running it and explicitly passing the flag that configure is supposed to set. But that's not very satisfactory.
Is there is a general way to pass an override to configure for the compiler? I tried setting -Wno-error in the CPPFLAGS and CFLAGS environment for configure, but the configtest program seems to ignore those. What seems to be going on is configure is seeing that gethostbyname_r doesn't exist and sets it to no but then later on still tests for it. I'm just wondering if there's a flag or something to get past this error, as it seems to me that whatever Apple did to break (or fix) Xcode after version 11.2 would have broken a lot of people's projects.
I am looking for a solution that does not involve modifying the program sources or the Autotools input files. The project manual is not helpful in this regard.
As an update: someone on the apcupsd list told me that this issue is fixed in a later version of Xcode. I have not tried that yet but when I do if that is what it proves out to be I'll post a followup
Is there is a general way to pass an override to configure for the
compiler? I tried setting -Wno-error in the CPPFLAGS and CFLAGS
environment for configure, but the configtest program seems to ignore
those.
If you set the CFLAGS or CPPFLAGS variable in configure's environment, then not only should configure use those flags when it builds test programs, but it should also memorialize the variable so that you don't need to specify it again to make. Indeed, this ...
What seems to be going on is configure is seeing that
gethostbyname_r doesn't exist and sets it to no
... suggests that it is doing so in your case.
In that event, if it seems to test again later, or else to fail in some other way despite determining that the function is not present, then that suggests a flaw in the project's own autotooling.
I'm just wondering if there's a flag or something
to get past this error,
You have already tried the most likely candidate (CFLAGS). Alternatively, you might also be able work around the issue through use of a cache file. That's still hacky, but I think less so than modifying the configure script. I'm afraid I have no specific guidance on doing this.
as it seems to me that whatever Apple did to
break (or fix) Xcode after version 11.2 would have broken a lot of
people's projects.
It did. That does not imply that there is a quick or easy solution, though it would be good news if indeed Apple solved the issue in a later version of Xcode.
So I have enabled -fsantize=address to write a good program.
However, quite a bit of issues was being caught by other libraries that are not written by me (for ex, /lib64/...so)
I looked into -fsantize-blacklist option but seems like it's only available for clang not for GCC.
I know you can blacklist specific functions in your source code. But to be honest, that is not the ideal way as I wouldn't know which function will cause the issue ahead of time.
Is there any way to prevent GCC from processing address sanitizer for files under a specific folder?
Please help :(
Unfortunately fsanitize-blacklist has been rejected by GCC maintainers several times and there's no equivalent option. You could add Clang support or use -fsanitize-recover=address together with export ASAN_OPTIONS=log_path=path/to/logs to collect errors from all libraries and then filter the ones that are relevant.
From some Googling around it seems that clang's support for windows has been improving recently and boost's support for clang may also have improved. But I'm fairly new to all this heavy-lifting compiler configuration stuff and new to boost, so I'm not sure what the current status really is.
I'm trying to run the command:
b2 --build-dir=build toolset=clang --build-type=complete stage
as suggested in section 5.2.4 in www.boost.org/.../getting_started/windows.
This does work to some extent, but watching the logs being printed to screen I see a few worrying things:
statements starting clang-linux.compile.c++.... even though I am on windows.
12 warnings generated. (or similar) perhaps always these are -Wunused-local-typedef, but I'm not sure.
2 warnings and 8 errors generated (or similar) surely if there are errors the build has failed? How am I supposed to know which component of boost has not built properly and what can I do to fix this?
I'm not clear whether I need MSVC the compiler, Visual Stufio the IDE, and/or MinGW and whether I need to manually set flags to pass to the compiler? Perhaps clang+boost is not ready for windows yet?
Ultimately I want to use boost.python, and at a later date maybe boost.coroutine.
Presumably if I want to use clang for my own projects I need to compile boost with clang too?
bootstrap --with-toolset=clang-win
b2 toolset=clang-win
Make sure that clang.exe is on your PATH.
I am learning compilers and want to make changes of my own to GCC parser and lexer. Is there any testing tool or some another way available which let me change gcc code and test it accordingly.
I tried changing the lexical analysis file but now I am stuck because I don't know how to compile these files. I tried the compilation using other GCC compiler but show errors. I even tried configure and make but doing this with every change does not seems efficient.
The purpose of these changes is just learning and I have to consider GCC only as this is the only compiler my instructor allowed.
I even tried configure and make but doing that wit every change is not at all efficient.
That is exactly what you should be doing. (Well, you don't need to re-configure after every change, just run make again.) However, by default GCC configures itself in bootstrap mode, which means not only does your host compiler compile GCC, that compiled GCC then compiles GCC again (and again). That is overkill for your purposes, and you can prevent that from happening by adding --disable-bootstrap to the configuration options.
Another option that can help significantly reduce build times is enabling only the languages you're interested in. Since you're experimenting, you'll likely be very happy if you create something that works for C or for C++, even if for some obscure reason Java happens to break. Testing other languages becomes relevant when you make your changes available for a larger audience, but that isn't the case just yet. The configuration option that covers this is --enable-languages=c,c++.
Most of the configuration options are documented on the Installing GCC: Configuration page. Throroughly testing your changes is documented on the Contributing to GCC page, but that's likely something for later: you should know how to make your own simpler tests pass, by simply trying code that makes use of your new feature.
You make changes (which are made "permanent" by saving the files you modify), compile the code, and run the test suite.
You typically write additional tests or remove those that are invalidated by your changes and that's it.
If your changes don't contribute anything "positive" to the compiler upstream will probably never accept them, and the only "permanence" you can get is the modifications in your local copy.