[yocto] using clang for one recipe

[Trevor Woerner]

On Fri 2017-06-23 @ 03:57:06 PM, Khem Raj wrote:
> On Fri, Jun 23, 2017 at 3:39 PM, Trevor Woerner <twoerner at gmail.com> wrote:
> > Adding that line, and adding meta-clang to bblayers.conf, did get the
> > llvm/clang compiler built and installed to recipe-sysroot-native. But
> > the moment it starts to build the package, it fails immediately with:
> >
> >     | fatal error: 'string' file not found
> >     | #include <string>
> >     |          ^~~~~~~~
> >
> > Did I miss a step? That seems like a pretty basic thing that would be
> > needed for using a toolchain. If feels like I'm missing something;
> > like I need to add something else to my local.conf. Thoughts?
> > Suggestions?
> 
> which package is it ? it seems its missing proper -I paths.?

I'm investigating moving chromium to a newer version, specifically something
much closer to the current Linux stable (59.0.3071.109). My understanding is
the chromium developers use clang, which would explain why it's always so much
work to get it to compile with gcc. If I can get chromium to build with clang,
I think it would make future maintenance much easier. Switching from gyp to gn
was easy, but getting this newer version to build with gcc7 is a challenge.

When I go to the recipe-sysroot-native, I find clang in usr/bin. But from that
base location if I do a

	$ find . -name "*string*" -print

I don't find any such include files. Should they not be installed to the
native sysroot alongside clang itself?

Here's one example of a failing compile:

| [16/25529] CXX obj/base/allocator/tcmalloc/sysinfo.o
| FAILED: obj/base/allocator/tcmalloc/sysinfo.o
| ../../../recipe-sysroot-native/usr/bin/clang++ -MMD -MF obj/base/allocator/tcmalloc/sysinfo.o.d -DNO_HEAP_CHECK -DV8_DEPRECATION_WARNINGS -DUSE_UDEV -DUSE_AURA=1 -DUSE_PANGO=1 -DUSE_CAIRO=1 -DUSE_GLIB=1 -DUSE_NSS_CERTS=1 -DUSE_X11=1 -DDISABLE_NACL -DFULL_SAFE_BROWSING -DSAFE_BROWSING_CSD -DSAFE_BROWSING_DB_LOCAL -DCHROMIUM_BUILD -DENABLE_MEDIA_ROUTER=1 -DFIELDTRIAL_TESTING_ENABLED -DCR_CLANG_REVISION=\"299960-1\" -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -DCOMPONENT_BUILD -D_DEBUG -DDYNAMIC_ANNOTATIONS_ENABLED=1 -DWTF_USE_DYNAMIC_ANNOTATIONS=1 -DTCMALLOC_FOR_DEBUGALLOCATION -DTCMALLOC_DONT_REPLACE_SYSTEM_ALLOC -I../../base/allocator -I../../third_party/tcmalloc/chromium/src/base -I../../third_party/tcmalloc/chromium/src -I../.. -Igen -fno-strict-aliasing --param=ssp-buffer-size=4 -fstack-protector -Wno-builtin-macro-redefined -D__DATE__= -D__TIME__= -D__TIMESTAMP__= -funwind-tables -fPIC -pipe -fcolor-diagnostics --target=arm-linux-gnueabihf -march=armv7-a -mfloat-abi=hard -mtune=generic-armv7-a -pthread -mfpu=neon -O0 -fno-omit-frame-pointer -g2 --sysroot=../../build/linux/debian_jessie_arm-sysroot -fvisibility=hidden -Wheader-hygiene -Wstring-conversion -Wtautological-overlap-compare -Wall -Wno-unused-variable -Wno-missing-field-initializers -Wno-unused-parameter -Wno-c++11-narrowing -Wno-covered-switch-default -Wno-unneeded-internal-declaration -Wno-inconsistent-missing-override -Wno-undefined-var-template -Wno-nonportable-include-path -Wno-address-of-packed-member -Wno-unused-lambda-capture -Wno-user-defined-warnings -Wno-reorder -Wno-unused-function -Wno-unused-local-typedefs -Wno-unused-private-field -Wno-sign-compare -Wno-unused-result -fvisibility-inlines-hidden -Wno-undefined-bool-conversion -Wno-tautological-undefined-compare -std=gnu++11 -fno-rtti -fno-exceptions -Wno-deprecated -c ../../third_party/tcmalloc/chromium/src/base/sysinfo.cc -o obj/base/allocator/tcmalloc/sysinfo.o
| In file included from ../../third_party/tcmalloc/chromium/src/base/sysinfo.cc:62:
| In file included from ../../third_party/tcmalloc/chromium/src/base/sysinfo.h:49:
| In file included from ../../third_party/tcmalloc/chromium/src/base/logging.h:49:
| ../../third_party/tcmalloc/chromium/src/base/commandlineflags.h:52:10: fatal error: 'string' file not found
| #include <string>
|          ^~~~~~~~
| 1 error generated.


I can send you the non-working, partial recipe if you're interested too.