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Author: gknowles

CMakeLists.txt

@@ -248,7 +248,7 @@ elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU")
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++2c")
     endif()
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-    if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "7")
+    if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "10")
         # The libstdc++6 library, as of 2021-06-15, no longer works with
         # Clang++-6 in c++2a mode, failing with a reference to the unknown
         # std::is_constant_evaluated().

appveyor.yml

@@ -15,15 +15,15 @@ environment:
 #      GENERATOR: Visual Studio 16 2019
 #      WINDOWS_SDK: 10.0.19041.0
 
-#    - CXX: clang++-6.0
-#      CC: clang-6.0
-#      APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu1604
-#      INSTALL_COMPILER: ON
+    - CXX: clang++-6.0
+      CC: clang-6.0
+      APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu1604
+      INSTALL_COMPILER: ON
+      CXXFLAGS: -stdlib=libc++
     - CXX: clang++-7
       CC: clang-7
       APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu1804
       INSTALL_COMPILER: ON
-      INSTALL_BEFORE: libc++-7-dev
       CXXFLAGS: -stdlib=libc++
 #    - CXX: clang++-8
 #      CC: clang-8
@@ -33,8 +33,6 @@ environment:
       CC: clang-9
       APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004
       INSTALL_COMPILER: ON
-      INSTALL_BEFORE: libc++-9-dev
-      CXXFLAGS: -stdlib=libc++
 #    - CXX: clang++-10
 #      CC: clang-10
 #      APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004