[cfe-users] Unexpected include directories when cross-compiling

[don hinton via cfe-users]

Take a look at the "Toolchain Options" and "Target-Specific Libraries"
sections here:

  http://clang.llvm.org/docs/CrossCompilation.html

Which will show you how to tell the compiler where to find stuff for your
target system.

hth...
don

On Tue, Sep 22, 2015 at 11:38 AM, Andreas Messer via cfe-users <
cfe-users at lists.llvm.org> wrote:

> Hello everybody,
>
> I'm currently planning to use clang to compile my ARM projects. One bug I
> found in clang 3.5 - it tried to link the elf using the host's instead of
> the
> target's linker - is fixed in trunk source. Unfortunately I found an issue
> with
> the include files which - in my oppinion - is wrong. When cross compiling
> for
> the arm target clang adds the hosts include folders to the include search
> paths by default:
>
> /tmp/test_clang $ clang -v --target=arm-none-eabi -c main.c -o main.o
> clang version 3.8.0 (http://llvm.org/git/clang.git
> 21b3f468fc871980e422404f35fcac7de83cfa9c) (llvm/trunk 248266)
> Target: arm-none--eabi
> Thread model: posix
> InstalledDir: /usr/local/bin
>  "/usr/local/stow/llvm_r248266-clang_r248254/bin/clang-3.8" -cc1 -triple
> armv4t-none--eabi -emit-obj -mrelax-all -disable-free
> -disable-llvm-verifier -
> main-file-name main.c -mrelocation-model static -mthread-model posix
> -mdisable-
> fp-elim -fmath-errno -masm-verbose -mconstructor-aliases -target-cpu
> arm7tdmi
> -target-feature +soft-float-abi -target-feature +strict-align -target-abi
> aapcs
> -mfloat-abi soft -v -dwarf-column-info -coverage-file
> /tmp/test_clang/main.o -
> resource-dir
> /usr/local/stow/llvm_r248266-clang_r248254/bin/../lib/clang/3.8.0
> -fdebug-compilation-dir /tmp/test_clang -ferror-limit 19 -fmessage-length
> 126
> -fallow-half-arguments-and-returns -fno-signed-char -fobjc-runtime=gcc -
> fdiagnostics-show-option -fcolor-diagnostics -o main.o -x c main.c
> clang -cc1 version 3.8.0 based upon LLVM 3.8.0svn default target x86_64-
> unknown-linux-gnu
> #include "..." search starts here:
> #include <...> search starts here:
>  /usr/local/include
>  /usr/local/stow/llvm_r248266-clang_r248254/bin/../lib/clang/3.8.0/include
>  /usr/include
> End of search list.
> main.c:5:11: warning: self-comparison always evaluates to true [-
> Wtautological-compare]
>   while(i == i)
>           ^
> 1 warning generated.
> /tmp/test_clang $
>
> This is not what I would expect, since this is wrong for cross compilation
> in
> almost any case. This can be somehow bypassed using -nostdinc option but
> then
> I have to manually add the .../lib/clang/3.8.0/include. What would be the
> best
> way to solve this?
>
> Another thing I noticed occurs when using the -sysroot option. clang then
> tries to use $sysroot/usr/include. In my oppinion it should use
> $sysroot/include instead.
>
> Kind regards,
> Andreas
>
>
>
> _______________________________________________
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> cfe-users at lists.llvm.org
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>
>
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