[cfe-dev] standalone tool: best way to find built-in includes?

[Sean Silva]

On Fri, Nov 21, 2014 at 8:00 AM, Manuel Klimek <klimek at google.com> wrote:

> On Fri Nov 21 2014 at 4:40:44 PM Christian Convey <
> christian.convey at gmail.com> wrote:
>
>> Hi Manuel,
>>
>> What really matters is that when my tool analyzes the target program's
>> source, it assumes the same standard headers that are normally used to
>> build that target program.
>>
>> For example, the target program might normally be built with clang
>> 3.4, but my analysis tool is built on clang 3.6.  When my tool
>> analyzes the source code of the target program, I want the analysis to
>> be as though the target program #include'd the 3.4 builtins, not the
>> 3.6 builtins.  Because my goal is to obtain the same AST as the one
>> created during the target program's normal (3.4) build process.
>>
>
> The builtin headers are implementation details of the compiler. If you
> compile a file with a tool based on clang 3.6 and builtin headers of clang
> 3.4 the probability that you *don't* get a correct AST is higher.
>

It's actually possible for it to fail to build with the wrong builtin
headers. E.g. an intrinsic was changed from using an __builtin_* function
to using a different one that is not present in the other compiler.

-- Sean Silva


>
> If you want to get the same AST, you have to use the same version of
> clang. The question is, why is it important to you whether it's the same
> AST?
>
>
>>
>> If I understand your suggestion, my analysis would give me an AST
>> based on the clang 3.6 builtins, not based on the 3.4 builtins.  Is
>> that correct?
>>
>> Thanks,
>> Christian
>>
>>
>>
>>
>>
>> On Fri, Nov 21, 2014 at 4:35 AM, Manuel Klimek <klimek at google.com> wrote:
>> > +1 to needs some refactoring, but generally the trick is: you don't
>> want to
>> > use the builtin includes that are used by the clang you used to produce
>> the
>> > compilation database, but the one that is current at the version at
>> which
>> > you built your *tool*.
>> >
>> > Thus, optimally you'll install your tool into some/bin and the builtin
>> > headers into some/lib/clang/<version>.
>> >
>> > Cheers,
>> > /Manuel
>> >
>> > On Fri Nov 21 2014 at 5:23:16 AM Sean Silva <chisophugis at gmail.com>
>> wrote:
>> >>
>> >> You can set CLANG_RESOURCE_DIR in CMake, or pass -resource-dir (the
>> >> default resource dir is created by `llvm::sys::path::append(<exe-
>> path>,
>> >> "..", "lib", "clang", CLANG_VERSION_STRING)`).
>> >>
>> >> This logic is actually duplicated in more than one place unfortunately.
>> >> e.g. in CompilerInvocation::GetResourcesPath
>> >> (lib/Frontend/CompilerInvocation.cpp) and Driver::Driver
>> >> (lib/Driver/Driver.cpp); there's also some nastiness in
>> >> CIndexer::getClangResourcesPath. Needs some refactoring.
>> >>
>> >> -- Sean Silva
>> >>
>> >> On Thu, Nov 20, 2014 at 6:32 PM, Christian Convey
>> >> <christian.convey at gmail.com> wrote:
>> >>>
>> >>> Hi guys,
>> >>>
>> >>> I'm developed a standalone tool for analyzing source code.  It uses
>> >>> CommonOptionParser and ClangTool in what I think are the standard
>> >>> ways.
>> >>>
>> >>> My tool analyzes some other code ("foo.c") we have.  We build foo.c
>> >>> with clang the system-wide installed version of clang.  Thanks to
>> >>> cmake, we also produce a compilation database for that build of foo.c.
>> >>>
>> >>> I'd really like to ensure that when my analysis tool runs, I'd like it
>> >>> to simulate, as closely as possible, the way we normally build foo.c.
>> >>> In particular, I'd like to be sure it's using the same builtin headers
>> >>> and gcc-provided headers.
>> >>>
>> >>> Unfortunately, I can't easily copy my analysis tools executable into
>> >>> the same directory as the clang which we use to build foo.c.
>> >>>
>> >>> So here's my question: Is there a good way for me to force my tool to
>> >>> search the same include directories, in the same order, as our normal
>> >>> copy of clang does when it's building foo.c?
>> >>>
>> >>> I've tried running "clang -### ..." in the build system for foo.c, so
>> >>> that (I think) I get explicit information about the flags being passed
>> >>> to the front-end.  However, I haven't found a way to pass those flags
>> >>> to my analysis tool in a way that CommonOptionsParser and/or ClangTool
>> >>> find acceptable.  For example, they reject "-cc1".
>> >>>
>> >>> Thanks,
>> >>> Christian
>> >>> _______________________________________________
>> >>> cfe-dev mailing list
>> >>> cfe-dev at cs.uiuc.edu
>> >>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>> >>
>> >>
>> >> _______________________________________________
>> >> cfe-dev mailing list
>> >> cfe-dev at cs.uiuc.edu
>> >> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>>
>
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