Use modern clang/libc++ for sanitizers (#1171)

* Use modern clang/libc++ for sanitizers

* update ubuntu

* new llvm builds differently

* clang, not clang-3.8

* just build what we need

.github/.libcxx-setup.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+
+# Checkout LLVM sources
+git clone --depth=1 https://github.com/llvm/llvm-project.git llvm-project
+
+# Setup libc++ options
+if [ -z "$BUILD_32_BITS" ]; then
+  export BUILD_32_BITS=OFF && echo disabling 32 bit build
+fi
+
+# Build and install libc++ (Use unstable ABI for better sanitizer coverage)
+cd ./llvm-project
+cmake -DCMAKE_C_COMPILER=${C_COMPILER}          \
+      -DCMAKE_CXX_COMPILER=${COMPILER}          \
+      -DCMAKE_BUILD_TYPE=RelWithDebInfo         \
+      -DCMAKE_INSTALL_PREFIX=/usr               \
+      -DLIBCXX_ABI_UNSTABLE=OFF                 \
+      -DLLVM_USE_SANITIZER=${LIBCXX_SANITIZER}  \
+      -DLLVM_BUILD_32_BITS=${BUILD_32_BITS}     \
+      -DLLVM_ENABLE_PROJECTS='libcxx;libcxxabi' \
+      -S llvm -B llvm-build -G "Unix Makefiles"
+make -C llvm-build -j3 cxx cxxabi
+sudo make -C llvm-build install-cxx install-cxxabi
+cd ..

.github/workflows/sanitizer.yml

@@ -5,15 +5,15 @@ on:
   pull_request: {}
 
 env:
-  CC: clang-3.8
-  CXX: clang++-3.8
+  CC: clang
+  CXX: clang++
   EXTRA_CXX_FLAGS: "-stdlib=libc++"
   UBSAN_OPTIONS: "print_stacktrace=1"
 
 jobs:
   job:
     name: ${{ matrix.sanitizer }}.${{ matrix.build_type }}
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
@@ -28,7 +28,7 @@ jobs:
       run: |
         echo "EXTRA_FLAGS=-g -O2 -fno-omit-frame-pointer -fsanitize=memory -fsanitize-memory-track-origins" >> $GITHUB_ENV
         echo "LIBCXX_SANITIZER=MemoryWithOrigins" >> $GITHUB_ENV
-        
+
     - name: configure ubsan env
       if: matrix.sanitizer == 'ubsan'
       run: |
@@ -47,13 +47,8 @@ jobs:
         echo "EXTRA_FLAGS=-g -O2 -fno-omit-frame-pointer -fsanitize=thread -fno-sanitize-recover=all" >> $GITHUB_ENV
         echo "LIBCXX_SANITIZER=Thread" >> $GITHUB_ENV
 
-    - name: install clang-3.8
-      run: |
-        sudo apt update
-        sudo apt -y install clang-3.8
-
-    - name: install libc++
-      run: "${GITHUB_WORKSPACE}/.libcxx-setup.sh"
+    - name: install llvm stuff
+      run: "${GITHUB_WORKSPACE}/.github/.libcxx-setup.sh"
 
     - name: create build environment
       run: cmake -E make_directory ${{ runner.workspace }}/_build
@@ -76,7 +71,7 @@ jobs:
       shell: bash
       working-directory: ${{ runner.workspace }}/_build
       run: cmake --build . --config ${{ matrix.build_type }}
-      
+
     - name: test
       shell: bash
       working-directory: ${{ runner.workspace }}/_build