Updating main branch for legacy libc++ support (#1288)

* Updating main branch for legacy libc++ support

* Adopting

* Removing unnecessary math header.

* Updating the single-header files so we can pass the new tests.

* Portable infinite-value detection is hard.

* Working toward disabling boost json selectively.

* Selectively disabling Boost JSON

* More work toward selectively disabling boost json.

.drone.yml

@@ -367,6 +367,27 @@ steps:
     - ctest $CTEST_FLAGS
 ---
 kind: pipeline
+name: libcpp-clang7
+platform: { os: linux, arch: amd64 }
+steps:
+- name: Build and Test
+  image: conanio/clang7
+  user: root
+  environment:
+    CC: clang-7
+    CXX: clang++-7
+    BUILD_FLAGS: -- -j
+    CMAKE_FLAGS: -DSIMDJSON_BUILD_STATIC=ON
+    CTEST_FLAGS: -j4 --output-on-failure -E checkperf
+    CXXFLAGS: -stdlib=libc++
+  commands:
+    - mkdir build
+    - cd build
+    - cmake $CMAKE_FLAGS ..
+    - cmake --build . $BUILD_FLAGS
+    - ctest $CTEST_FLAGS
+---
+kind: pipeline
 name: noexceptions-gcc9
 platform: { os: linux, arch: amd64 }
 steps:

benchmark/parsingcompetition.cpp

@@ -27,8 +27,16 @@ SIMDJSON_PUSH_DISABLE_ALL_WARNINGS
 #include <nlohmann/json.hpp>
 using json = nlohmann::json;
 
+#if defined(__clang__)
+// Under some clang/libc++ configurations, boost json fails
+// to build.
+#define DISABLE_BOOST_JSON
+#endif
+
+#ifndef DISABLE_BOOST_JSON
 #include <boost/json/parser.hpp>
 #include <boost/json/monotonic_resource.hpp>
+#endif
 
 #ifdef ALLPARSER
 
@@ -175,7 +183,7 @@ bool bench(const char *filename, bool verbose, bool just_data,
             std::memcpy(buffer, p.data(), p.size()) &&
                 (buffer[p.size()] = '\0'),
             repeat, volume, !just_data);
-
+#ifndef DISABLE_BOOST_JSON
   {
     const boost::json::string_view sv(p.data(), p.size());
     boost::json::parser p;
@@ -191,6 +199,7 @@ bool bench(const char *filename, bool verbose, bool just_data,
 
     BEST_TIME("Boost.json", execute(sv), false, , repeat, volume, !just_data);
   }
+#endif
   {
 
     auto execute = [&p]() -> bool {

dependencies/CMakeLists.txt

@@ -67,17 +67,25 @@ if ((Git_FOUND) AND SIMDJSON_GIT AND (SIMDJSON_IS_UNDER_GIT))
     add_library(competition-ujson4c ujson4c/src/ujdecode.c)
     target_include_directories(competition-ujson4c PUBLIC ujson4c/3rdparty ujson4c/src)
 
-    initialize_submodule(boost.json)
-    add_library(boostjson boost.json/src/src.cpp)
-    target_compile_definitions(boostjson PUBLIC BOOST_JSON_STANDALONE)
-    target_include_directories(boostjson PUBLIC boost.json/include)
+    # Boost JSON is not compatible with some clang/libc++ configurations.
+    if (NOT CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+      initialize_submodule(boost.json)
+      add_library(boostjson boost.json/src/src.cpp)
+      target_compile_definitions(boostjson PUBLIC BOOST_JSON_STANDALONE)
+      target_include_directories(boostjson PUBLIC boost.json/include)
+    endif()
 
     initialize_submodule(yyjson)
     add_library(yyjson yyjson/src/yyjson.c)
     target_include_directories(yyjson PUBLIC yyjson/src)
 
     add_library(competition-core INTERFACE)
-    target_link_libraries(competition-core INTERFACE competition-json competition-rapidjson competition-sajson competition-cJSON competition-jsmn boostjson yyjson)
+    # Boost JSON is not compatible with some clang/libc++ configurations.
+    if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+      target_link_libraries(competition-core INTERFACE competition-json competition-rapidjson competition-sajson competition-cJSON competition-jsmn yyjson)
+    else()
+      target_link_libraries(competition-core INTERFACE competition-json competition-rapidjson competition-sajson competition-cJSON competition-jsmn boostjson yyjson)
+    endif()
 
     add_library(competition-all INTERFACE)
     target_link_libraries(competition-all INTERFACE competition-core competition-jsoncppdist competition-json11 competition-fastjson competition-gason competition-ujson4c)

include/simdjson/generic/numberparsing.h

@@ -1,5 +1,4 @@
 #include "simdjson/internal/numberparsing_tables.h"
-#include <cmath>
 #include <limits>
 
 namespace simdjson {
@@ -292,8 +291,20 @@ simdjson_really_inline bool compute_float_64(int64_t power, uint64_t i, bool neg
 // one digit.
 static bool parse_float_fallback(const uint8_t *ptr, double *outDouble) {
   *outDouble = simdjson::internal::from_chars((const char *)ptr);
-  // We do not accept infinite values.
-  if (!std::isfinite(*outDouble)) {
+  // We do not accept infinite values. Detecting finite values in a portable manner is ridiculously hard.
+  //
+  // Next line would be nice but if fails under Visual Studio with error C2589: '(': illegal token on right side of '::'
+  // despite the fact that we have '#include <limits>' above.
+  // if ((*outDouble > std::numeric_limits<double>::max()) || (*outDouble < std::numeric_limits<double>::lowest())) {
+  //
+  // Next line would be better but it mysteriously fails under legacy/old libc++ libraries.
+  // See https://github.com/simdjson/simdjson/issues/1286
+  //if (!std::isfinite(*outDouble)) {
+  //
+  // So we use the following that ought to work under all systems.
+  // (Note that I also tried hexadecimal floats but it failed under some systems too.)
+  //
+  if ((*outDouble > 1.7976931348623157E+308) || (*outDouble < -1.7976931348623157E+308)) {
     return false;
   }
   return true;

src/from_chars.cpp

@@ -1,4 +1,3 @@
-#include <cmath>
 #include <limits>
 namespace simdjson {
 namespace internal {

src/to_chars.cpp

@@ -1,4 +1,3 @@
-#include <cmath>
 #include <cstring>
 #include <cstdint>
 #include <array>
@@ -914,8 +913,7 @@ format. Returns an iterator pointing past-the-end of the decimal representation.
 */
 char *to_chars(char *first, const char *last, double value) {
   static_cast<void>(last); // maybe unused - fix warning
-  // Use signbit(value) instead of (value < 0) since signbit works for -0.
-  if (std::signbit(value)) {
+  if (value <= -0) {
     value = -value;
     *first++ = '-';
   }