build: support linking against libc++ on Linux.

.bazelrc

@@ -49,5 +49,13 @@ build:clang-msan --define tcmalloc=disabled
 build:clang-msan --copt -fsanitize-memory-track-origins=2
 build:clang-msan --linkopt -fuse-ld=lld
 
+# Clang with libc++
+build:libc++ --action_env=CC
+build:libc++ --action_env=CXX
+build:libc++ --action_env=CXXFLAGS=-stdlib=libc++
+build:libc++ --action_env=PATH
+build:libc++ --define force_libcpp=enabled
+build:libc++ --linkopt -fuse-ld=lld
+
 # Test options
 test --test_env=HEAPCHECK=normal --test_env=PPROF_PATH

.circleci/config.yml

@@ -4,7 +4,7 @@ executors:
   ubuntu-build:
     description: "A regular build executor based on ubuntu image"
     docker:
-      - image: envoyproxy/envoy-build:284769e833cc7752812f076a8b7a12e79c948df9
+      - image: envoyproxy/envoy-build:c1fde9909df98373be1fd2cc0733caf1f91917a6
     resource_class: xlarge
     working_directory: /source
 

bazel/README.md

@@ -82,6 +82,18 @@ Bazel can also be built with the Docker image used for CI, by installing Docker
 See also the [documentation](https://github.com/envoyproxy/envoy/tree/master/ci) for developer use of the
 CI Docker image.
 
+## Linking against libc++ on Linux
+
+To link Envoy against libc++, use the following commands:
+```
+export CC=clang
+export CXX=clang++
+bazel build --config=libc++ //source/exe:envoy-static
+```
+Note: this assumes that both: clang compiler and libc++ library are installed in the system,
+and that `clang` and `clang++` are available in `$PATH`. On some systems, exports might need
+to be changed to versioned binaries, e.g. `CC=clang-7` and `CXX=clang++-7`.
+
 ## Using a compiler toolchain in a non-standard location
 
 By setting the `CC` and `LD_LIBRARY_PATH` in the environment that Bazel executes from as

bazel/cc_configure.bzl

@@ -64,6 +64,7 @@ def _build_envoy_cc_wrapper(repository_ctx):
     repository_ctx.template("extra_tools/envoy_cc_wrapper", repository_ctx.attr._envoy_cc_wrapper, {
         "{ENVOY_REAL_CC}": repr(str(real_cc)),
         "{ENVOY_REAL_CXX}": repr(str(real_cxx)),
+        "{ENVOY_CXXFLAGS}": repr(str(repository_ctx.os.environ.get("CXXFLAGS", ""))),
     })
     return repository_ctx.path("extra_tools/envoy_cc_wrapper")
 
@@ -91,25 +92,27 @@ cc_autoconf = repository_rule(
         "ABI_VERSION",
         "BAZEL_COMPILER",
         "BAZEL_HOST_SYSTEM",
+        "BAZEL_LINKOPTS",
         "BAZEL_PYTHON",
         "BAZEL_SH",
         "BAZEL_TARGET_CPU",
         "BAZEL_TARGET_LIBC",
         "BAZEL_TARGET_SYSTEM",
         "BAZEL_USE_CPP_ONLY_TOOLCHAIN",
+        "BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN",
+        "BAZEL_USE_LLVM_NATIVE_COVERAGE",
         "BAZEL_VC",
         "BAZEL_VS",
+        "BAZEL_LLVM",
+        "USE_CLANG_CL",
         "CC",
         "CXX",
+        "CXXFLAGS",
         "CC_CONFIGURE_DEBUG",
         "CC_TOOLCHAIN_NAME",
         "CPLUS_INCLUDE_PATH",
-        "CUDA_COMPUTE_CAPABILITIES",
-        "CUDA_PATH",
+        "GCOV",
         "HOMEBREW_RUBY_PATH",
-        "NO_WHOLE_ARCHIVE_OPTION",
-        "USE_DYNAMIC_CRT",
-        "USE_MSVC_WRAPPER",
         "SYSTEMROOT",
         "VS90COMNTOOLS",
         "VS100COMNTOOLS",

bazel/cc_wrapper.py

@@ -1,11 +1,13 @@
 #!/usr/bin/python
 import contextlib
 import os
+import shlex
 import sys
 import tempfile
 
 envoy_real_cc = {ENVOY_REAL_CC}
 envoy_real_cxx = {ENVOY_REAL_CXX}
+envoy_cxxflags = {ENVOY_CXXFLAGS}
 
 
 @contextlib.contextmanager
@@ -21,20 +23,14 @@ def sanitize_flagfile(in_path, out_fd):
     for line in in_fp:
       if line != "-lstdc++\n":
         os.write(out_fd, line)
+      elif "-stdlib=libc++" in envoy_cxxflags:
+        os.write(out_fd, "-lc++\n")
 
 
 def main():
-  compiler = envoy_real_cc
-
-  # Debian's packaging of Clang requires `-no-canonical-prefixes` to print
-  # consistent include paths, but Bazel 0.10 only sets that option at compile
-  # time. We inject it here for the configuration of `@local_config_cc//`.
-  #
-  # https://github.com/bazelbuild/bazel/issues/3977
-  # https://github.com/bazelbuild/bazel/issues/4572
-  # https://bazel-review.googlesource.com/c/bazel/+/39951
-  if sys.argv[1:] == ["-E", "-xc++", "-", "-v"] and "clang" in compiler:
-    os.execv(envoy_real_cxx, [envoy_real_cxx, "-E", "-", "-v", "-no-canonical-prefixes"])
+  # Append CXXFLAGS to correctly detect include paths for either libstdc++ or libc++.
+  if sys.argv[1:5] == ["-E", "-xc++", "-", "-v"]:
+    os.execv(envoy_real_cxx, [envoy_real_cxx] + sys.argv[1:] + shlex.split(envoy_cxxflags))
 
   # `g++` and `gcc -lstdc++` have similar behavior and Bazel treats them as
   # interchangeable, but `gcc` will ignore the `-static-libstdc++` flag.
@@ -45,10 +41,22 @@ def main():
   # it in the same test.
   if "-static-libstdc++" in sys.argv[1:] or "-stdlib=libc++" in sys.argv[1:]:
     compiler = envoy_real_cxx
-    argv = []
+  else:
+    compiler = envoy_real_cc
+
+  # Either:
+  # a) remove all occurrences of -lstdc++ (when statically linking against libstdc++),
+  # b) replace all occurrences of -lstdc++ with -lc++ (when linking against libc++).
+  if "-static-libstdc++" in sys.argv[1:] or "-stdlib=libc++" in envoy_cxxflags:
+    # Append CXXFLAGS to all C++ targets (this is mostly for dependencies).
+    if envoy_cxxflags and "-std=c++" in str(sys.argv[1:]):
+      argv = shlex.split(envoy_cxxflags)
+    else:
+      argv = []
     for arg in sys.argv[1:]:
       if arg == "-lstdc++":
-        pass
+        if "-stdlib=libc++" in envoy_cxxflags:
+          arg.append("-lc++")
       elif arg.startswith("-Wl,@"):
         # tempfile.mkstemp will write to the out-of-sandbox tempdir
         # unless the user has explicitly set environment variables

bazel/envoy_build_system.bzl

@@ -86,6 +86,8 @@ def envoy_copts(repository, test = False):
 
 def envoy_static_link_libstdcpp_linkopts():
     return envoy_select_force_libcpp(
+        # TODO(PiotrSikora): statically link libc++ once that's possible.
+        # See: https://reviews.llvm.org/D53238
         ["-stdlib=libc++"],
         ["-static-libstdc++", "-static-libgcc"],
     )
@@ -161,7 +163,7 @@ def envoy_test_linkopts():
         # TODO(mattklein123): It's not great that we universally link against the following libs.
         # In particular, -latomic and -lrt are not needed on all platforms. Make this more granular.
         "//conditions:default": ["-pthread", "-lrt", "-ldl"],
-    }) + envoy_select_force_libcpp(["-lc++experimental"], ["-lstdc++fs", "-latomic"])
+    }) + envoy_select_force_libcpp(["-lc++fs"], ["-lstdc++fs", "-latomic"])
 
 # References to Envoy external dependencies should be wrapped with this function.
 def envoy_external_dep_path(dep):

ci/build_container/Makefile

@@ -9,8 +9,8 @@ CC ?= gcc
 CXX ?= g++
 
 # Common compiler flags
-CXXFLAGS ?= -ggdb3 -fno-omit-frame-pointer -O2
-CFLAGS ?= -ggdb3 -fno-omit-frame-pointer -O2
+CXXFLAGS += -ggdb3 -fno-omit-frame-pointer -O2
+CFLAGS += -ggdb3 -fno-omit-frame-pointer -O2
 CPPFLAGS ?= -DNDEBUG
 
 # Keep track of the env vars we depend upon for $(THIRDPARTY_DEPS)/%.dep.env. If the list (captured

ci/build_container/build_recipes/gperftools.sh

@@ -14,5 +14,8 @@ curl https://github.com/gperftools/gperftools/releases/download/gperftools-"$VER
 tar xf gperftools-"$VERSION".tar.gz
 cd gperftools-"$VERSION"
 
-LDFLAGS="-lpthread" ./configure --prefix="$THIRDPARTY_BUILD" --enable-shared=no --enable-frame-pointers --disable-libunwind
-make V=1 install
+export LDFLAGS="${LDFLAGS} -lpthread"
+./configure --prefix="$THIRDPARTY_BUILD" --enable-shared=no --enable-frame-pointers --disable-libunwind
+
+# Don't build tests, since malloc_extension_c_test hardcodes -lstdc++, which breaks build when linking against libc++.
+make V=1 install-libLTLIBRARIES install-perftoolsincludeHEADERS

ci/do_ci.sh

@@ -152,17 +152,19 @@ elif [[ "$1" == "bazel.compile_time_options" ]]; then
   # Right now, none of the available compile-time options conflict with each other. If this
   # changes, this build type may need to be broken up.
   COMPILE_TIME_OPTIONS="\
+    --config libc++ \
     --define signal_trace=disabled \
     --define hot_restart=disabled \
     --define google_grpc=disabled \
     --define boringssl=fips \
     --define log_debug_assert_in_release=enabled \
-    --define=tcmalloc=debug \
+    --define tcmalloc=debug \
   "
   setup_clang_toolchain
   # This doesn't go into CI but is available for developer convenience.
   echo "bazel with different compiletime options build with tests..."
-  cd "${ENVOY_CI_DIR}"
+  # Building all the dependencies from scratch to link them against libc++.
+  cd "${ENVOY_SRCDIR}"
   echo "Building..."
   bazel build ${BAZEL_BUILD_OPTIONS} ${COMPILE_TIME_OPTIONS} -c dbg //source/exe:envoy-static
   echo "Building and testing..."

test/common/upstream/ring_hash_lb_test.cc

@@ -177,7 +177,7 @@ TEST_P(RingHashFailoverTest, BasicFailover) {
   EXPECT_EQ(failover_host_set_.healthy_hosts_[0], lb->chooseHost(nullptr));
 }
 
-#ifndef __APPLE__
+#if __GLIBCXX__ >= 20130411 && __GLIBCXX__ <= 20180726
 // Run similar tests with the default hash algorithm for GCC 5.
 // TODO(danielhochman): After v1 is deprecated this test can be deleted since std::hash will no
 // longer be in use.

test/exe/envoy_static_test.sh

@@ -17,7 +17,9 @@ fi
 if [[ ${DYNLIBS} =~ "libc++" ]]; then
   echo "libc++ is dynamically linked:"
   echo "${DYNLIBS}"
-  exit 1
+  # TODO(PiotrSikora): enforce this once there is a way to statically link libc++.
+  # See: https://reviews.llvm.org/D53238
+  exit 0
 fi
 
 if [[ ${DYNLIBS} =~ "libstdc++" || ${DYNLIBS} =~ "libgcc" ]]; then