diff --git a/.drone.star b/.drone.star
index f96e2947..17478359 100644
--- a/.drone.star
+++ b/.drone.star
@@ -14,12 +14,6 @@ windowsglobalimage="cppalliance/dronevs2019"
 
 def main(ctx):
   return [
-  linux_cxx("g++-5 14", "g++-5", packages="g++-5", buildtype="boost", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-5', 'CXXSTD': '14', }, globalenv=globalenv),
-  linux_cxx("g++-5 1z", "g++-5", packages="g++-5", buildtype="boost", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-5', 'CXXSTD': '1z', }, globalenv=globalenv),
-  
-  linux_cxx("g++-6 14", "g++-6", packages="g++-6", buildtype="boost", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-6', 'CXXSTD': '14', }, globalenv=globalenv),
-  linux_cxx("g++-6 1z", "g++-6", packages="g++-6", buildtype="boost", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-6', 'CXXSTD': '1z', }, globalenv=globalenv),
-
   linux_cxx("g++-7 14", "g++-7", packages="g++-7", buildtype="boost", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-7', 'CXXSTD': '14', }, globalenv=globalenv),
   linux_cxx("g++-7 17", "g++-7", packages="g++-7", buildtype="boost", image=linuxglobalimage, environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-7', 'CXXSTD': '17', }, globalenv=globalenv),
 
@@ -33,23 +27,15 @@ def main(ctx):
   linux_cxx("g++-10 14", "g++-10", packages="g++-10", image="cppalliance/droneubuntu2004:1", buildtype="boost", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-10', 'CXXSTD': '14', }, globalenv=globalenv),
   linux_cxx("g++-10 17", "g++-10", packages="g++-10", image="cppalliance/droneubuntu2004:1", buildtype="boost", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-10', 'CXXSTD': '17', }, globalenv=globalenv),
   linux_cxx("g++-10 20", "g++-10", packages="g++-10", image="cppalliance/droneubuntu2004:1", buildtype="boost", environment={'TOOLSET': 'gcc', 'COMPILER': 'g++-10', 'CXXSTD': '20', }, globalenv=globalenv),
-
-  linux_cxx("clang++-4.0 14", "clang++-4.0", packages="clang-4.0", llvm_os="xenial", llvm_ver="4.0", buildtype="boost", image=linuxglobalimage, environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-4.0', 'CXXSTD': '14', }, globalenv=globalenv),
-
-  linux_cxx("clang++-5.0 14", "clang++-5.0", packages="clang-5.0", llvm_os="xenial", llvm_ver="5.0", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-5.0', 'CXXSTD': '14', }, globalenv=globalenv),
-  
-  linux_cxx("clang++-6.0 14", "clang++-6.0", packages="clang-6.0", llvm_os="xenial", llvm_ver="6.0", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-6.0', 'CXXSTD': '14', }, globalenv=globalenv),
   
   linux_cxx("clang++-7 14", "clang++-7", packages="clang-7", llvm_os="xenial", llvm_ver="7", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-7', 'CXXSTD': '14', }, globalenv=globalenv),
   linux_cxx("clang++-7 17", "clang++-7", packages="clang-7", llvm_os="xenial", llvm_ver="7", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-7', 'CXXSTD': '17', }, globalenv=globalenv),
   
   linux_cxx("clang++-8 14", "clang++-8", packages="clang-8", llvm_os="xenial", llvm_ver="8", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-8', 'CXXSTD': '14', }, globalenv=globalenv),
   linux_cxx("clang++-8 17", "clang++-8", packages="clang-8", llvm_os="xenial", llvm_ver="8", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-8', 'CXXSTD': '17', }, globalenv=globalenv),
-  linux_cxx("clang++-8 2a", "clang++-8", packages="clang-8", llvm_os="xenial", llvm_ver="8", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-8', 'CXXSTD': '2a', }, globalenv=globalenv),
 
   linux_cxx("clang++-9 14", "clang++-9", packages="clang-9", llvm_os="xenial", llvm_ver="9", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-9', 'CXXSTD': '14', }, globalenv=globalenv),
   linux_cxx("clang++-9 17", "clang++-9", packages="clang-9", llvm_os="xenial", llvm_ver="9", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-9', 'CXXSTD': '17', }, globalenv=globalenv),
-  linux_cxx("clang++-9 2a", "clang++-9", packages="clang-9", llvm_os="xenial", llvm_ver="9", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-9', 'CXXSTD': '2a', }, globalenv=globalenv),
 
   linux_cxx("clang++-10 14", "clang++-10", packages="clang-10", llvm_os="xenial", llvm_ver="10", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-10', 'CXXSTD': '14', }, globalenv=globalenv),
   linux_cxx("clang++-10 17", "clang++-10", packages="clang-10", llvm_os="xenial", llvm_ver="10", buildtype="boost", image="cppalliance/droneubuntu1804:1", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++-10', 'CXXSTD': '17', }, globalenv=globalenv),
@@ -57,7 +43,6 @@ def main(ctx):
 
   osx_cxx("XCode-11.7 14", "clang++", packages="", buildtype="boost", xcode_version="11.7", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '14', }, globalenv=globalenv),
   osx_cxx("XCode-11.7 17", "clang++", packages="", buildtype="boost", xcode_version="11.7", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '17', }, globalenv=globalenv),
-  osx_cxx("XCode-11.7 2a", "clang++", packages="", buildtype="boost", xcode_version="11.7", environment={'TOOLSET': 'clang', 'COMPILER': 'clang++', 'CXXSTD': '2a', }, globalenv=globalenv),
   ]
 
 # from https://github.com/boostorg/boost-ci