[BUILD] Need fine-grained HAVE_CPP_STDLIB

CMakeLists.txt

@@ -115,7 +115,10 @@ endif()
 
 option(WITH_NO_DEPRECATED_CODE "Do not include deprecated code" OFF)
 
-option(WITH_STL "Whether to use Standard Library for C++ latest features" OFF)
+set(WITH_STL
+    "OFF"
+    CACHE STRING "Which version of the Standard Library for C++ to use")
+
 option(WITH_GSL
        "Whether to use Guidelines Support Library for C++ latest features" OFF)
 
@@ -130,22 +133,7 @@ option(OPENTELEMETRY_INSTALL "Whether to install opentelemetry targets"
 
 include("${PROJECT_SOURCE_DIR}/cmake/tools.cmake")
 
-if(NOT DEFINED CMAKE_CXX_STANDARD)
-  if(WITH_STL)
-    # Require at least C++17. C++20 is needed to avoid gsl::span
-    if(CMAKE_VERSION VERSION_GREATER 3.11.999)
-      # Ask for 20, may get anything below
-      set(CMAKE_CXX_STANDARD 20)
-    else()
-      # Ask for 17, may get anything below
-      set(CMAKE_CXX_STANDARD 17)
-    endif()
-  else()
-    set(CMAKE_CXX_STANDARD 11)
-  endif()
-endif()
-
-if(WITH_STL)
+if(NOT WITH_STL STREQUAL "OFF")
   # These definitions are needed for test projects that do not link against
   # opentelemetry-api library directly. We ensure that variant implementation
   # (absl::variant or std::variant) in variant unit test code is consistent with

api/CMakeLists.txt

@@ -51,11 +51,33 @@ if(WITH_ABSEIL)
        "absl_bits" "absl_city")
 endif()
 
-if(WITH_STL)
-  message("Building with standard library types...")
-  target_compile_definitions(opentelemetry_api INTERFACE HAVE_CPP_STDLIB)
+if(WITH_STL STREQUAL "OFF")
+  message(STATUS "Building WITH_STL=OFF")
+  target_compile_definitions(opentelemetry_api
+                             INTERFACE OPENTELEMETRY_STL_VERSION=0)
+elseif(WITH_STL STREQUAL "CXX11")
+  message(STATUS "Building WITH_STL=CXX1")
+  target_compile_definitions(opentelemetry_api
+                             INTERFACE OPENTELEMETRY_STL_VERSION=2011)
+elseif(WITH_STL STREQUAL "CXX14")
+  message(STATUS "Building WITH_STL=CXX14")
+  target_compile_definitions(opentelemetry_api
+                             INTERFACE OPENTELEMETRY_STL_VERSION=2014)
+elseif(WITH_STL STREQUAL "CXX17")
+  message(STATUS "Building WITH_STL=CXX17")
+  target_compile_definitions(opentelemetry_api
+                             INTERFACE OPENTELEMETRY_STL_VERSION=2017)
+elseif(WITH_STL STREQUAL "CXX20")
+  message(STATUS "Building WITH_STL=CXX20")
+  target_compile_definitions(opentelemetry_api
+                             INTERFACE OPENTELEMETRY_STL_VERSION=2020)
+elseif(WITH_STL STREQUAL "ON")
+  message(STATUS "Building WITH_STL=ON")
+  # "ON" corresponds to "CXX20" at this time.
+  target_compile_definitions(opentelemetry_api
+                             INTERFACE OPENTELEMETRY_STL_VERSION=2020)
 else()
-  message("Building with nostd types...")
+  message(FATAL_ERROR "WITH_STL must be ON, OFF, CXX11, CXX14, CXX17 or CXX20")
 endif()
 
 if(WITH_GSL)

api/include/opentelemetry/nostd/shared_ptr.h

@@ -2,7 +2,8 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #pragma once
-#ifdef HAVE_CPP_STDLIB
+
+#if OPENTELEMETRY_STL_VERSION >= 2011
 #  include "opentelemetry/std/shared_ptr.h"
 #else
 #  include <cstdlib>

api/include/opentelemetry/nostd/span.h

@@ -4,7 +4,7 @@
 #pragma once
 
 // Try to use either `std::span` or `gsl::span`
-#ifdef HAVE_CPP_STDLIB
+#if OPENTELEMETRY_STL_VERSION >= 2020
 #  include <array>
 #  include <cstddef>
 #  include <iterator>
@@ -26,7 +26,7 @@
 #  if OPENTELEMETRY_OPTION_USE_STD_SPAN
 #    include "opentelemetry/std/span.h"
 #  endif
-#endif
+#endif /* OPENTELEMETRY_STL_VERSION >= 2020 */
 
 // Fallback to `nostd::span` if necessary
 #if !defined(HAVE_SPAN)

api/include/opentelemetry/nostd/string_view.h

@@ -3,7 +3,7 @@
 
 #pragma once
 
-#ifdef HAVE_CPP_STDLIB
+#if OPENTELEMETRY_STL_VERSION >= 2017
 #  include "opentelemetry/std/string_view.h"
 #else
 #  include <algorithm>

api/include/opentelemetry/nostd/type_traits.h

@@ -3,7 +3,7 @@
 
 #pragma once
 
-#ifdef HAVE_CPP_STDLIB
+#if OPENTELEMETRY_STL_VERSION >= 2011
 #  include "opentelemetry/std/type_traits.h"
 #else
 #  include <array>
@@ -154,4 +154,4 @@ struct is_trivially_move_assignable
 #  endif
 }  // namespace nostd
 OPENTELEMETRY_END_NAMESPACE
-#endif
+#endif /* OPENTELEMETRY_STL_VERSION >= 2011 */

api/include/opentelemetry/nostd/unique_ptr.h

@@ -3,7 +3,7 @@
 
 #pragma once
 
-#ifdef HAVE_CPP_STDLIB
+#if OPENTELEMETRY_STL_VERSION >= 2011
 #  include "opentelemetry/std/unique_ptr.h"
 #else
 #  include <cstddef>

api/include/opentelemetry/nostd/utility.h

@@ -3,7 +3,7 @@
 
 #pragma once
 
-#ifdef HAVE_CPP_STDLIB
+#if OPENTELEMETRY_STL_VERSION >= 2014
 #  include "opentelemetry/std/utility.h"
 #else
 

api/include/opentelemetry/nostd/variant.h

@@ -5,7 +5,7 @@
 
 #include "opentelemetry/version.h"
 
-#ifdef HAVE_CPP_STDLIB
+#if OPENTELEMETRY_STL_VERSION >= 2017
 #  include "opentelemetry/std/variant.h"
 #else
 

api/test/nostd/span_test.cc

@@ -60,11 +60,6 @@ TEST(SpanTest, PointerCountConstruction)
   span<int, 3> s2{array.data(), array.size()};
   EXPECT_EQ(s2.data(), array.data());
   EXPECT_EQ(s2.size(), array.size());
-
-#ifndef HAVE_CPP_STDLIB
-  /* This test is not supposed to fail with STL. Why is this invalid construct? */
-  EXPECT_DEATH((span<int, 2>{array.data(), array.size()}), ".*");
-#endif
 }
 
 TEST(SpanTest, RangeConstruction)
@@ -78,11 +73,6 @@ TEST(SpanTest, RangeConstruction)
   span<int, 3> s2{std::begin(array), std::end(array)};
   EXPECT_EQ(s2.data(), array);
   EXPECT_EQ(s2.size(), 3);
-
-#ifndef HAVE_CPP_STDLIB
-  /* This test is not supposed to fail with STL. Why is this invalid construct? */
-  EXPECT_DEATH((span<int, 2>{std::begin(array), std::end(array)}), ".*");
-#endif
 }
 
 TEST(SpanTest, ArrayConstruction)
@@ -122,11 +112,6 @@ TEST(SpanTest, ContainerConstruction)
   EXPECT_EQ(s2.data(), v.data());
   EXPECT_EQ(s2.size(), v.size());
 
-#ifndef HAVE_CPP_STDLIB
-  /* This test is not supposed to fail with STL. Why is this invalid construct? */
-  EXPECT_DEATH((span<int, 2>{v.data(), 3}), ".*");
-#endif
-
   EXPECT_FALSE((std::is_constructible<span<int>, std::vector<double>>::value));
   EXPECT_FALSE((std::is_constructible<span<int>, std::list<int>>::value));
 }

api/test/nostd/string_view_test.cc

@@ -71,7 +71,7 @@ TEST(StringViewTest, SubstrPortion)
 TEST(StringViewTest, SubstrOutOfRange)
 {
   string_view s = "abc123";
-#if __EXCEPTIONS || defined(HAVE_CPP_STDLIB)
+#if __EXCEPTIONS || (OPENTELEMETRY_STL_VERSION >= 2020)
   EXPECT_THROW(s.substr(10), std::out_of_range);
 #else
   EXPECT_DEATH({ s.substr(10); }, "");

ext/test/http/CMakeLists.txt

@@ -25,7 +25,7 @@ endif()
 set(URL_PARSER_FILENAME url_parser_test)
 add_executable(${URL_PARSER_FILENAME} ${URL_PARSER_FILENAME}.cc)
 target_link_libraries(${URL_PARSER_FILENAME} ${GTEST_BOTH_LIBRARIES}
-                      ${CMAKE_THREAD_LIBS_INIT})
+                      ${CMAKE_THREAD_LIBS_INIT} opentelemetry_api)
 gtest_add_tests(
   TARGET ${URL_PARSER_FILENAME}
   TEST_PREFIX ext.http.urlparser.