[PATCH] D37631: [libFuzzer] Support using libc++

[Kostya Serebryany via Phabricator via llvm-commits]

kcc added a comment.

could you please also add a lit test that uses -stdlib=libc++?



================
Comment at: CMakeLists.txt:355
 else()
-  set(COMPILER_RT_LIBCXX_PATH ${LLVM_MAIN_SRC_DIR}/../libcxx)
+  set(COMPILER_RT_LIBCXX_PATH ${LLVM_MAIN_SRC_DIR}/runtimes/libcxx)
   if(EXISTS ${COMPILER_RT_LIBCXX_PATH}/)
----------------
phosek wrote:
> kcc wrote:
> > Hm... 
> > Why ${LLVM_MAIN_SRC_DIR}/runtimes/libcxx ? 
> > 
> > Also, is this related to libFuzzer? 
> > Could this be a separate patch? 
> That's an alternate location for libc++ when cross-compiling runtimes (e.g. this is used by Fuchsia's toolchain build). Another one would be for monorepo layout. I'm fine splitting this into a separate change.
Yes, please. 
This looks like completely independent from libFuzzer and I'd like someone from libcxx to review it. 


================
Comment at: lib/fuzzer/CMakeLists.txt:35
 
+if(CMAKE_CXX_COMPILER_ID MATCHES Clang AND COMPILER_RT_HAS_LIBCXX_SOURCES)
+  list(APPEND LIBFUZZER_CFLAGS -stdlib=libc++ -D_LIBCPP_ABI_VERSION=Fuzzer)
----------------
phosek wrote:
> kcc wrote:
> > Why is this guarded with "CMAKE_CXX_COMPILER_ID MATCHES Clang"? 
> This is so we can use `-stdlib=libc++` with Clang so it automatically includes the correct path to libc++ headers. Alternative would be to use `-nostdinc++`  and manually add the path to libc++ headers to `CFLAGS`. That would work for GCC as well.
I see... 


================
Comment at: lib/fuzzer/tests/CMakeLists.txt:22
+if(CMAKE_CXX_COMPILER_ID MATCHES Clang AND COMPILER_RT_HAS_LIBCXX_SOURCES)
+  list(APPEND LIBFUZZER_UNITTEST_CFLAGS -stdlib=libc++ -D_LIBCPP_ABI_VERSION=Fuzzer)
+endif()
----------------
phosek wrote:
> kcc wrote:
> > Why do we need stdlib=libc++ for unit tests? 
> > 
> > I'd rather have a separate lit test in test/fuzzer that uses stdlib=libc++. 
> This is the same as in the other `CMakeLists.txt` file, the solution mentioned there would work here as well.
Ah, yea, the unit tests are linked with the guts of libFuzzer and so they need -stdlib=libc++. Got it. 


Repository:
  rCRT Compiler Runtime

https://reviews.llvm.org/D37631