Let us see if we can test with libc++. (#732)

* Let us see if we can test with libc++.
* Fixed spacing.

.circleci/config.yml

@@ -25,6 +25,13 @@ executors:
           CXX: g++
           BUILD_FLAGS: -j
           CTEST_FLAGS: -j4 --output-on-failure
+  clang9:
+    docker:
+      - image: conanio/clang9
+        environment:
+          CXX: clang++-9
+          BUILD_FLAGS: -j
+          CTEST_FLAGS: -j4 --output-on-failure
 
   clang6:
     docker:
@@ -50,10 +57,13 @@ commands:
       - run: make test
       - run: make checkperf
 
-  cmake_prep:
+  install_cmake:
     steps:
       - run: apt-get update -qq
       - run: apt-get install -y cmake
+
+  cmake_prep:
+    steps:
       - checkout
 
   cmake_build:
@@ -78,6 +88,7 @@ commands:
       - run: SIMDJSON_FORCE_IMPLEMENTATION=fallback ctest $CTEST_FLAGS -L per_implementation
       - run: ctest $CTEST_FLAGS -LE "acceptance|per_implementation" # Everything we haven't run yet, run now.
 
+
   # we not only want cmake to build and run tests, but we want also a successful installation from which we can build, link and run programs
   cmake_install_test: # this version builds, install, test and then verify from the installation
     steps:
@@ -91,60 +102,65 @@ jobs:
     description: Build and run tests on GCC 7 and AVX 2 with a cmake static build
     executor: gcc7
     environment: { CMAKE_FLAGS: -DSIMDJSON_GOOGLE_BENCHMARKS=ON }
-    steps: [ cmake_test_all, cmake_install_test ]
+    steps: [ install_cmake, cmake_test_all, cmake_install_test ]
   clang6:
     description: Build and run tests on clang 6 and AVX 2 with a cmake static build
     executor: clang6
     environment: { CMAKE_FLAGS: -DSIMDJSON_GOOGLE_BENCHMARKS=ON }
-    steps: [ init_clang6, cmake_test_all, cmake_install_test ]
-  
+    steps: [ init_clang6, install_cmake, cmake_test_all, cmake_install_test ]
+  # libcpp
+  libcpp-clang9:
+    description: Build and run tests on clang 6 and AVX 2 with a cmake static build and libc++
+    executor: clang9
+    environment: { CMAKE_FLAGS: -DSIMDJSON_USE_LIBCPP=ON }
+    steps: [ cmake_test_all, cmake_install_test ]
   # sanitize
   sanitize-gcc9:
     description: Build and run tests on GCC 9 and AVX 2 with a cmake sanitize build
     executor: gcc9
     environment: { CMAKE_FLAGS: -DSIMDJSON_BUILD_STATIC=OFF -DSIMDJSON_SANITIZE=ON, CTEST_FLAGS: -j4 --output-on-failure -E checkperf }
-    steps: [ cmake_test_all ]
+    steps: [ install_cmake, cmake_test_all ]
   sanitize-clang6:
     description: Build and run tests on clang 6 and AVX 2 with a cmake sanitize build
     executor: clang6
     environment: { CMAKE_FLAGS: -DSIMDJSON_BUILD_STATIC=OFF -DSIMDJSON_SANITIZE=ON, CTEST_FLAGS: -j4 --output-on-failure -E checkperf }
-    steps: [ init_clang6, cmake_test_all ]
+    steps: [ init_clang6, install_cmake, cmake_test_all ]
   
   # dynamic
   dynamic-gcc7:
     description: Build and run tests on GCC 7 and AVX 2 with a cmake dynamic build
     executor: gcc7
     environment: { CMAKE_FLAGS: -DSIMDJSON_BUILD_STATIC=OFF }
-    steps: [ cmake_test, cmake_install_test ]
+    steps: [ install_cmake, cmake_test, cmake_install_test ]
   dynamic-clang6:
     description: Build and run tests on clang 6 and AVX 2 with a cmake dynamic build
     executor: clang6
     environment: { CMAKE_FLAGS: -DSIMDJSON_BUILD_STATIC=OFF }
-    steps: [ init_clang6, cmake_test, cmake_install_test ]
+    steps: [ init_clang6, install_cmake, cmake_test, cmake_install_test ]
   
   # unthreaded
   unthreaded-gcc7:
     description: Build and run tests on GCC 7 and AVX 2 *without* threads
     executor: gcc7
     environment: { CMAKE_FLAGS: -DSIMDJSON_ENABLE_THREADS=OFF }
-    steps: [ cmake_test, cmake_install_test ]
+    steps: [ install_cmake, cmake_test, cmake_install_test ]
   unthreaded-clang6:
     description: Build and run tests on Clang 6 and AVX 2 *without* threads
     executor: clang6
     environment: { CMAKE_FLAGS: -DSIMDJSON_ENABLE_THREADS=OFF }
-    steps: [ init_clang6, cmake_test, cmake_install_test ]
+    steps: [ init_clang6, install_cmake, cmake_test, cmake_install_test ]
 
   # noexcept
   noexcept-gcc7:
     description: Build and run tests on GCC 7 and AVX 2 with exceptions off
     executor: gcc7
     environment: { CMAKE_FLAGS: -DSIMDJSON_EXCEPTIONS=OFF }
-    steps: [ cmake_test, cmake_install_test ]
+    steps: [ install_cmake, cmake_test, cmake_install_test ]
   noexcept-clang6:
     description: Build and run tests on GCC 7 and AVX 2 with exceptions off
     executor: clang6
     environment: { CMAKE_FLAGS: -DSIMDJSON_EXCEPTIONS=OFF }
-    steps: [ init_clang6, cmake_test, cmake_install_test ]
+    steps: [ init_clang6, install_cmake, cmake_test, cmake_install_test ]
 
   #
   # Misc.
@@ -175,6 +191,9 @@ workflows:
       - gcc7
       - clang6
       
+      # libc++
+      - libcpp-clang9
+      
       # full single-implementation tests
       - sanitize-gcc9
       - sanitize-clang6

CMakeLists.txt

@@ -25,11 +25,13 @@ if(MSVC)
 else()
   option(SIMDJSON_BUILD_STATIC "Build a static library" OFF) # turning it on disables the production of a dynamic library
   option(SIMDJSON_COMPETITION "Compile competitive benchmarks" ON)
+  option(SIMDJSON_USE_LIBCPP "Use the libc++ library" OFF)
 endif()
 option(SIMDJSON_GOOGLE_BENCHMARKS "compile the Google Benchmark benchmarks" OFF)
 
 set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/tools/cmake")
 
+
 # We compile tools, tests, etc. with C++ 17. Override yourself if you need on a target.
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
@@ -38,6 +40,7 @@ set(CMAKE_MACOSX_RPATH OFF)
 set(CMAKE_THREAD_PREFER_PTHREAD ON)
 set(THREADS_PREFER_PTHREAD_FLAG ON)
 
+
 # LTO seems to create all sorts of fun problems. Let us
 # disable temporarily.
 #include(CheckIPOSupported)
@@ -58,6 +61,17 @@ else()
   target_compile_options(simdjson-flags INTERFACE -Werror -Wall -Wextra -Wsign-compare -Wshadow -Wwrite-strings -Wpointer-arith -Winit-self)
 endif()
 
+
+if(SIMDJSON_USE_LIBCPP)
+  target_link_libraries(simdjson-flags INTERFACE -stdlib=libc++ -lc++abi)
+  # instead of the above line, we could have used
+  # set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -stdlib=libc++  -lc++abi")
+  # The next line is needed empirically.
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")
+  # we update CMAKE_SHARED_LINKER_FLAGS, this gets updated later as well
+  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -lc++abi")
+endif(SIMDJSON_USE_LIBCPP)
+
 # Optional flags
 option(SIMDJSON_IMPLEMENTATION_HASWELL "Include the haswell implementation" ON)
 if(NOT SIMDJSON_IMPLEMENTATION_HASWELL)

examples/quickstart/CMakeLists.txt

@@ -3,7 +3,13 @@
 #
 
 # TODO haven't quite decided the right way to run quickstart on Windows. Needs README update.
-if (NOT MSVC)
+#
+# Note: on macOS and other platforms, the 'command' described below may not work even if the cmake builds.
+# For example, it may be necessary to specify the sysroot, which CMake does, but the 'command' does not
+# handle such niceties. On a case-by-case basis it is fixable but it requires work that CMake knows how
+# to do but that is not trivial.
+#
+IF(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
   # TODO run amalgamate first!
   function(add_quickstart_test TEST_NAME SOURCE_FILE)
     # Second argument is C++ standard name

include/simdjson/common_defs.h

@@ -121,11 +121,49 @@ constexpr size_t DEFAULT_MAX_DEPTH = 1024;
 
 #endif // MSC_VER
 
-//
-// Backfill std::string_view using nonstd::string_view on C++11
-//
-#if (!SIMDJSON_CPLUSPLUS17)
 
+
+// C++17 requires string_view.
+#if SIMDJSON_CPLUSPLUS17
+#define SIMDJSON_HAS_STRING_VIEW
+#endif
+
+// This macro (__cpp_lib_string_view) has to be defined
+// for C++17 and better, but if it is otherwise defined,
+// we are going to assume that string_view is available
+// even if we do not have C++17 support.
+#ifdef __cpp_lib_string_view
+#define SIMDJSON_HAS_STRING_VIEW
+#endif
+
+// Some systems have string_view even if we do not have C++17 support,
+// and even if __cpp_lib_string_view is undefined, it is the case
+// with Apple clang version 11.
+// We must handle it. *This is important.*
+#ifndef SIMDJSON_HAS_STRING_VIEW
+#if defined __has_include
+// do not combine the next #if with the previous one (unsafe)
+#if __has_include (<string_view>)
+// now it is safe to trigger the include
+#include <string_view> // though the file is there, it does not follow that we got the implementation
+#if defined(_LIBCPP_STRING_VIEW)
+// Ah! So we under libc++ which under its Library Fundamentals Technical Specification, which preceeded C++17,
+// included string_view.
+// This means that we have string_view *even though* we may not have C++17.
+#define SIMDJSON_HAS_STRING_VIEW
+#endif // _LIBCPP_STRING_VIEW
+#endif // __has_include (<string_view>)
+#endif // defined __has_include
+#endif // def SIMDJSON_HAS_STRING_VIEW
+// end of complicated but important routine to try to detect string_view.
+
+//
+// Backfill std::string_view using nonstd::string_view on systems where
+// we expect that string_view is missing. Important: if we get this wrong,
+// we will end up with two string_view definitions and potential trouble.
+// That is why we work so hard above to avoid it.
+//
+#ifndef SIMDJSON_HAS_STRING_VIEW
 SIMDJSON_PUSH_DISABLE_ALL_WARNINGS
 #include "simdjson/nonstd/string_view.hpp"
 SIMDJSON_POP_DISABLE_WARNINGS
@@ -133,6 +171,7 @@ SIMDJSON_POP_DISABLE_WARNINGS
 namespace std {
   using string_view = nonstd::string_view;
 }
-#endif // if (SIMDJSON_CPLUSPLUS < 201703L)
+#endif // SIMDJSON_HAS_STRING_VIEW
+#undef SIMDJSON_HAS_STRING_VIEW // We are not going to need this macro anymore.
 
 #endif // SIMDJSON_COMMON_DEFS_H