[cfe-dev] Using clang::tooling::RefactoringTool on cross-compiled code with different /usr/include

[Александр Шапошников via cfe-dev]

just in case,
I'm wondering if your compilation commands explicitly contain
--sysroot or -isysroot, i.e. see
https://gcc.gnu.org/onlinedocs/gcc/Directory-Options.html
(these are gcc docs, but clang supports these options (since clang tries to
be a drop-in replacement for gcc).
Kind regards,
Alexander Shaposhnikov

On Fri, Mar 23, 2018 at 12:52 AM, Иванов Игорь via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> Hello everyone! It seems that my previous email got tumbled away as a html
> attachment, so I've removed all the formating in hope that helps.
>
> I am writing a tool using clang's  tooling::RefactoringTool  and want to
> apply it to ARM targeted sources. Those rely on their own sysroot to
> compile, which is incomplete and basically contains only lib and usr
> directories with proprietary stuff. Its  /usr/include  headers also differ
> from my system ones - so when parsing my sources with clang tool I get a
> lot of parsing errors related to header ordering, etc. And of course, with
> vendor-provided gcc4.8 everything is fine, which led me to a conclusion
> there's something wrong with how I use clang.
>
> I've tried to surpass the problem by copying my  /lib/clang/5.0.1/include
> to this sysroot (so clang builtin headers would work correctly with new
> include & lib) and changing my  compile_commands.json  to use  -nostdinc++
> -isystem /arm-hisiv300-linux/target/usr/include -isystem
> /arm-hisiv300-linux/gcc/include  - so clang wouldn't rely on system
> headers.
>
> Unforntunately it doesn't fool clang - it still tries to search for some
> headers in my host system:
>
> $ arm-hisiv300-linux/bin/my-tool src/grabcommon/rtp_assemblers.cpp
> In file included from src/grabcommon/rtp_assemblers.cpp:1:
> ...
> In file included from /arm-hisiv300-linux/target/usr/include/limits.h:125:
> <- here #include_next is used to access compiler-specific <limits.h>
> In file included from /arm-hisiv300-linux/bin/../lib/clang/5.0.1/include/limits.h:37:
> <- here clang #include_next <limits.h>
> >>> /usr/include/limits.h:145:5 <<< error: function-like macro
> '__GLIBC_USE' is not defined <- here I'd expect /arm-hisiv300-linux/target/usr/include/limits.h,
> but get system one
> #if __GLIBC_USE (IEC_60559_BFP_EXT)
>
> I believe I have to pass "sysroot" directory as an argument to my tool and
> somehow construct RefactoringTool / CompilationDatabase instance so it take
> advantage of needed include directory, but how? Or am I entirely wrong and
> this calls for drastic measures like recompiling clang/LLVM for my needs? I
> am aware that I can  mount --bind my/usr/include /usr/include  (it works!),
> or put everything to some arm-based distro and use qemu, so instead of
> cross-compiling I just compile in place. However my intention is that the
> tool could be used as simple as  $ my-tool --sysroot /dir file.cpp . So
> what are my options?
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