clang up to >=7

clang <= 7 can work with nameof, but will not be tested

.travis.yml

@@ -39,34 +39,6 @@ matrix:
       env:
         - CXX_COMPILER=g++-9 CC_COMPILER=gcc-9
 
-    - os: linux
-      compiler: clang++
-      addons:
-        apt:
-          sources:
-            - ubuntu-toolchain-r-test
-            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-5.0 main'
-              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
-          packages:
-            - g++-7
-            - clang-5.0
-      env:
-        - CXX_COMPILER=clang++-5.0 CC_COMPILER=clang-5.0
-
-    - os: linux
-      compiler: clang++
-      addons:
-        apt:
-          sources:
-            - ubuntu-toolchain-r-test
-            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-6.0 main'
-              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
-          packages:
-            - g++-7
-            - clang-6.0
-      env:
-        - CXX_COMPILER=clang++-6.0 CC_COMPILER=clang-6.0
-
     - os: linux
       compiler: clang++
       addons:

README.md

@@ -113,7 +113,7 @@ If you are using [Conan](https://www.conan.io/) to manage your dependencies, mer
 
 ## Compiler compatibility
 
-* Clang/LLVM >= 5
+* Clang/LLVM >= 7
 * Visual C++ >= 15.3 / Visual Studio >= 2017
 * Xcode >= 10
 * GCC >= 7 (GCC >= 9 for NAMEOF_ENUM)