When compiling, and specifically at the ./configure stage, remembering that --extra-cflags stands for extra compiler allows me to remember that option helps me pass extra options to the compiler I'm using. I understand that options like these reference variables that are set in the MAKE file?, but I don't understand what the rest of them stand for.
For example, I know that --extra-ldflags passes extra flags to the linker, but I'm not sure what that extra d is doing there. The help for the configure that I am looking at also lists --extra-ldexeflags and --extra-ldsoflags. Searching provides information on what some of the above options do, but nothing on what they actually stand for, which is a crucial step for me in being able to recall what they do.
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I'm cross-compling with mingw and got this error:
undefined reference to `rpl_realloc'
After some searching I found this can be resolved as follows in configure.ac or as environment variables set prior to calling ./mingw64-configure:
ac_cv_func_malloc_0_nonnull=yes
ac_cv_func_realloc_0_nonnull=yes
What defines these macros, and as there any documentation on the subject? I couldn't find any...
What defines these macros, and as there any documentation on the subject?
Autoconf uses the ac_cv_ prefix for its "cache variables", in which it records the results of configuration tests it has performed. In the event that the same check is requested multiple times, these allow it to use the previously-determined result instead of performing the check again.
The general naming convention for these is documented in the Autoconf manual. The particular cache variable names you ask about are documented to cache the results of the Autoconf's AC_FUNC_MALLOC and AC_FUNC_REALLOC macros, respectively. That documentation also speaks to the rpl_realloc name.
It is allowed to use these variables in configure.ac to programmatically determine the results of those checks, but it is a relatively nasty hack to assign values to those variables directly. In this particular case, however, the error suggests that whoever prepared the autotooling for the project you're trying to build did a sloppy job of it. If fudging the cache variables gets you a successful build and a working program then that's a tempting and much easier alternative to actually fixing the project.
I have a #define ONB in a c file which (with several #ifndef...#endifs) changes many aspects of a programs behavior. Now I want to change the project makefile (or even better Makefile.am) so that if ONB is defined and some other options are set accordingly, it runs some special commands.
I searched the web but all i found was checking for environment variables... So is there a way to do this? Or I must change the c code to check for that in environment variables?(I prefer not changing the code because it is a really big project and i do not know everything about it)
Questions: My level is insufficient to ask in comments so I will have to ask here:
How and when is the define added to the target in the first place?
Do you essentially want a way to be able to post compile query the binaries to to determine if a particular define was used?
It would be helpful if you could give a concrete example, i.e. what are the special commands you want run, and what are the .c .h files involved?
Possible solution: Depending on what you need you could use LLVM tools to maybe generate and examine the AST of your code to see if a define is used. But this seems a little like over engineering.
Possible solution: You could also use #includes to pull in .c or header files and a conditional error be generated, or compile (to a .o), then if the compile fails you know it is defined or not. But this has it's own issues depending on how things are set-up in your make file.
I just compiled code using the compiler option "-frecord-gcc-switches" to see which options the compiler selects automatically. Now I can see the options in section .GCC.command.line. There are several plausible compiler options but also one I cannot find any documentation about. What does -auxbase-strip png.o mean. Obviously it does something with png.o, but what does it do exactly?
Google search shows:
Hei Chan:
I am trying to find the document for auxbase and auxbase-strip,
but I can't find any.
Ian Lance Taylor:
They are internal options used to support the -fcompare-debug options.
They are not intended to be used by end users.
So, if you really want to know what this option does, you'll need to read GCC source (but you shouldn't care).
Is it possible to write your own gnatcheck rules, and if so, can someone point me to a good reference? I am searching for a particular "style" that is being used, and would love if I could simply write a rule that says if you see said style, it will throw up a warning, or an error, this way we can flag when this isn't following a particular standard.
A bit of background may be helpful here. While the style checks hold out a lot of promise for enforcing user style guidelines, that isn't exactly what they are for.
The main purpose of those checks is to enforce Ada Core's (The folks who maintain the compiler) style on the sources of the Ada compiler itself. You may notice that the checks get automatically turned on if you try compiling one of the compiler's own source files.
It doesn't really serve AdaCore's purposes at all if the styles enforced by the checks themselves are user-configurable, so they added no feature like that.
Your first option if you want to use it yourself is to just stick to AdaCore's coding style. I haven't found it horrible in the past, so you may just look at doing that.
Still, making some kind of configurability would be a really cool feature for somebody to add. If you go this route, you probably would have to make it configurable (with the current behavior as the default), rather than just changing the checks. The reason is that you'd have to modify the compiler sources to accomplish this, and as I mentioned above, the compiler turns the checks on when compiling itself. You really don't want to have to reformat a ton of working Gnat compiler source files.
I'd really like to see someone do this at some point, as it would make the checks much more useful to those of us who work for someone besides AdaCore.
In addition to trashgod's reference, I think Section 7.1 of this PDF might be of some help:
http://extranet.eu.adacore.com/articles/HighIntegrityAda.pdf
For reference, the existing GNAT style checking is described in the GNAT User's Guide under ยง3.2.5 Style Checking. As the rules are enforced by the compiler, additional rules would require corresponding modifications.
Can somebody please enlighten me as to what the command line flag to CMake might be that will make it print out all the compile/link commands it executes?
I can't find this anywhere in the documentation. Many hours of my life have just evaporated. I'd just like to verify it's doing what I think it is, (then banish the infernal build system altogether and replace it with a GNU Makefile).
Thank you!
The verbose argument should do what you want.
Content copied (with format adjusted slightly) here for future reference:
CMake/Verbose output
CMake has a nice colored output which hides the commandline. This is pretty to look at in the long run but sometimes when you write your configurations you want to know if you got all the compiler flags right. There is two ways to disable the pretty output, well, it's essentialy the same but still two different ways.
The first way is to simply run make with the additional argument "VERBOSE=1". This will show each command being run for this session, which is the most useful way to see if the flags is correct:
make VERBOSE=1
The second way is to permanently disable the pretty output in your CMakeLists.txt by setting CMAKE_VERBOSE_MAKEFILE:
set( CMAKE_VERBOSE_MAKEFILE on )
Content is available under Attribution-ShareAlike 2.5 unless otherwise noted.
Setting CMAKE_VERBOSE_MAKEFILE Works but the generator must be make. Documentation seems to assume this the case. Should probably be explicitly noted there.