Rename LDFLAGS into FUZZER_LDFLAGS

[mikea]

No description provided.

[mikea]

Several builds had same problems after the switch: the library itself fails to build:

(harfbuzz, also boringssl)

---------------------------------------------------------------
Compiling libFuzzer into /work/libfuzzer ...Done.
CC=clang
CXX=clang++
CFLAGS=-g -fsanitize=address -fsanitize-coverage=edge,indirect-calls,8bit-counters
CXXFLAGS=-g -fsanitize=address -fsanitize-coverage=edge,indirect-calls,8bit-counters -stdlib=libc++
FUZZER_LDFLAGS=-Wl,-whole-archive /usr/local/lib/libc++.a /usr/local/lib/libc++abi.a -Wl,-no-whole-archive
---------------------------------------------------------------
  CXXLD    main
/usr/local/bin/../lib/clang/4.0.0/lib/linux/libclang_rt.asan_cxx-x86_64.a(ubsan_type_hash_itanium.cc.o): In function `isDerivedFromAtOffset(__cxxabiv1::__class_type_info const*, __cxxabiv1::__class_type_info const*, long) [clone .constprop.0]':
/src/llvm/projects/compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cc:120: undefined reference to `typeinfo for __cxxabiv1::__si_class_type_info'
/src/llvm/projects/compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cc:120: undefined reference to `typeinfo for __cxxabiv1::__class_type_info'
/src/llvm/projects/compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cc:126: undefined reference to `__dynamic_cast'
/src/llvm/projects/compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cc:130: undefined reference to `typeinfo for __cxxabiv1::__vmi_class_type_info'
/src/llvm/projects/compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cc:130: undefined reference to `__dynamic_cast'
/usr/local/bin/../lib/clang/4.0.0/lib/linux/libclang_rt.asan_cxx-x86_64.a(ubsan_type_hash_itanium.cc.o): In function `isDerivedFromAtOffset':
/src/llvm/projects/compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cc:126: undefined reference to `__dynamic_cast'
/src/llvm/projects/compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cc:130: undefined reference to `typeinfo for __cxxabiv1::__vmi_class_type_info'
/src/llvm/projects/compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cc:130: undefined reference to `__dynamic_cast'
/src/llvm/projects/compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cc:126: undefined reference to `__dynamic_cast'
/src/llvm/projects/compiler-rt/lib/ubsan/ubsan_type_hash_itanium.cc:130: undefined reference to `typeinfo for __cxxabiv1::__vmi_class_type_info'

We need to do add export LDFLAGS=$FUZZER_LDFLAGS for the build to work. We don't specify any linker options at all.

@kcc @eugenis do you think this is wrong handling of sanitizer arguments in the presence of stdlib=libc++?

[kcc]

Not sure I understand you .
export LDFLAGS=$FUZZER_LDFLAGS SGTM
(or just do LDFLAGS=$FUZZER_LDFLAGS build-command)

[mikea]

The question is: why do I need to do this export at all?

The library is building some binary. And that binary can't be linked with -fsanitize=address -fsanitize-coverage without messing with linker arguments. I thought frontend will take care of linker arguments automagically.

[kcc]

I still don't understand the question.
In the current setup LDFLAGS adss static libc++.a, the frontend does not know about it
and will not add it automatically .

[mikea]

I have filed a bug for the driver: https://llvm.org/bugs/show_bug.cgi?id=30919