Revamp CMake files to be more understandable and correct

.appveyor.yml

@@ -3,9 +3,6 @@ os:
 - Visual Studio 2017
 
 build_script:
-  - git submodule update --init --recursive
-  - mkdir build
-  - cd build
-  - cmake ..
-  - cmake --build .
-  - C:\projects\optional\build\Debug\tests.exe
+  - cmake -Bbuild -S.
+  - cmake --build build
+  - cmake --build build --target RUN_TESTS

.gitignore

@@ -1,2 +1,3 @@
 \#*
 .\#*
+/build/

.travis.yml

@@ -1,257 +1,163 @@
 language: cpp
 
-
 dist: xenial
-sudo: false
 
 matrix:
   include:
     - compiler: gcc
-      addons:
-        apt:
-          sources:
-             - ubuntu-toolchain-r-test
-          packages:
-             - g++-5
-      env: COMPILER=g++-5 CXXSTD=11  
+      addons: { apt: { sources: ubuntu-toolchain-r-test, packages: g++-4.8 } }
+      env: COMPILER=g++-4.8 CXXSTD=11
     - compiler: gcc
-      addons:
-        apt:
-          sources:
-             - ubuntu-toolchain-r-test
-          packages:
-             - g++-6
+      addons: { apt: { sources: ubuntu-toolchain-r-test, packages: g++-4.9 } }
+      env: COMPILER=g++-4.9 CXXSTD=11
+    - &gcc-5
+      compiler: gcc
+      addons: { apt: { sources: ubuntu-toolchain-r-test, packages: g++-5 } }
+      env: COMPILER=g++-5 CXXSTD=11
+    - &gcc-6
+      compiler: gcc
+      addons: { apt: { sources: ubuntu-toolchain-r-test, packages: g++-6 } }
       env: COMPILER=g++-6 CXXSTD=11
-    - compiler: gcc
-      addons:
-        apt:
-          sources:
-             - ubuntu-toolchain-r-test
-          packages:
-             - g++-7
+    - &gcc-7
+      compiler: gcc
+      addons: { apt: { sources: ubuntu-toolchain-r-test, packages: g++-7 } }
       env: COMPILER=g++-7 CXXSTD=11
-    - compiler: gcc
-      addons:
-        apt:
-          sources:
-             - ubuntu-toolchain-r-test
-          packages:
-             - g++-8
+    - &gcc-8
+      compiler: gcc
+      addons: { apt: { sources: ubuntu-toolchain-r-test, packages: g++-8 } }
       env: COMPILER=g++-8 CXXSTD=11
-    - compiler: gcc
-      addons:
-        apt:
-          sources:
-             - ubuntu-toolchain-r-test
-          packages:
-             - g++-4.9
-      env: COMPILER=g++-4.9 CXXSTD=11
-    - compiler: gcc
-      addons:
-        apt:
-          sources:
-             - ubuntu-toolchain-r-test
-          packages:
-             - g++-4.8
-      env: COMPILER=g++-4.8 CXXSTD=11
-    - compiler: clang
-      addons:
-        apt:
-          sources:
-             - llvm-toolchain-precise-3.5
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-3.5
-             - libc++-dev
+    - &gcc-9
+      compiler: gcc
+      addons: { apt: { sources: ubuntu-toolchain-r-test, packages: g++-9 } }
+      env: COMPILER=g++-9 CXXSTD=11
+    - &clang-35
+      compiler: clang
+      addons:
+        apt: 
+          sources: [llvm-toolchain-precise-3.5, ubuntu-toolchain-r-test]
+          packages: [clang++-3.5, libc++-dev]
       env: COMPILER=clang++-3.5 CXXSTD=11
-    - compiler: clang
+    - &clang-36
+      compiler: clang
       addons:
-        apt:
-          sources:
-             - llvm-toolchain-precise-3.6
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-3.6
-             - libc++-dev
+        apt: 
+          sources: [llvm-toolchain-precise-3.6, ubuntu-toolchain-r-test]
+          packages: [clang++-3.6, libc++-dev]
       env: COMPILER=clang++-3.6 CXXSTD=11
-    - compiler: clang
+    - &clang-37
+      compiler: clang
       addons:
-        apt:
-          sources:
-             - llvm-toolchain-precise-3.7
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-3.7
-             - libc++-dev
+        apt: 
+          sources: [llvm-toolchain-precise-3.7, ubuntu-toolchain-r-test]
+          packages: [clang++-3.7, libc++-dev]
       env: COMPILER=clang++-3.7 CXXSTD=11
-    - compiler: clang
+    - &clang-38
+      compiler: clang
       addons:
         apt:
           sources:
-             - llvm-toolchain-precise-3.8
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-3.8
-             - libc++-dev
+            - &xenial-clang
+              sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-3.8 main'
+              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
+          packages: [clang++-3.8, libc++-dev]
       env: COMPILER=clang++-3.8 CXXSTD=11
-    - compiler: clang
+    - &clang-39
+      compiler: clang
       addons:
         apt:
           sources:
-            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-3.9 main"
-              key_url: "http://apt.llvm.org/llvm-snapshot.gpg.key"
+            - <<: *xenial-clang
+              sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-3.9 main'
             - ubuntu-toolchain-r-test
-          packages:
-            - clang++-3.9
-            - libc++-dev
+          packages: [clang++-3.9, libc++-dev]
       env: COMPILER=clang++-3.9 CXXSTD=11
-    - compiler: clang
+    - &clang-4
+      compiler: clang
       addons:
         apt:
           sources:
-             - llvm-toolchain-xenial-4.0
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-4.0
-             - libc++-dev
+            - <<: *xenial-clang
+              sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-4.0 main'
+            - ubuntu-toolchain-r-test
+          packages: [clang++-4.0, libc++-dev] 
       env: COMPILER=clang++-4.0 CXXSTD=11
-    - compiler: clang
+    - &clang-5
+      compiler: clang
       addons:
         apt:
           sources:
-             - llvm-toolchain-xenial-5.0
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-5.0
-             - libc++-dev
+            - <<: *xenial-clang
+              sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-5.0 main'
+            - ubuntu-toolchain-r-test
+          packages: [clang++-5.0, libc++-dev]
       env: COMPILER=clang++-5.0 CXXSTD=11
-    - compiler: clang
+    - &clang-6
+      compiler: clang
       addons:
         apt:
-          sources:
-             - llvm-toolchain-xenial-6.0
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-6.0
-             - libc++-dev
+          sources: [llvm-toolchain-xenial-6.0, ubuntu-toolchain-r-test]
+          packages: [clang++-6.0, libc++-dev]
       env: COMPILER=clang++-6.0 CXXSTD=11
-
-    - compiler: gcc
-      addons:
-        apt:
-          sources:
-             - ubuntu-toolchain-r-test
-          packages:
-             - g++-5
-      env: COMPILER=g++-5 CXXSTD=14
-    - compiler: gcc
-      addons:
-        apt:
-          sources:
-             - ubuntu-toolchain-r-test
-          packages:
-             - g++-6
-      env: COMPILER=g++-6 CXXSTD=14
-    - compiler: gcc
-      addons:
-        apt:
-          sources:
-             - ubuntu-toolchain-r-test
-          packages:
-             - g++-7
-      env: COMPILER=g++-7 CXXSTD=14
-    - compiler: gcc
-      addons:
-        apt:
-          sources:
-             - ubuntu-toolchain-r-test
-          packages:
-             - g++-8
-      env: COMPILER=g++-8 CXXSTD=14
-    - compiler: clang
+    - &clang-7
+      compiler: clang
       addons:
         apt:
-          sources:
-             - llvm-toolchain-precise-3.5
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-3.5
-             - libc++-dev
-      env: COMPILER=clang++-3.5 CXXSTD=14
-    - compiler: clang
+          sources: [llvm-toolchain-xenial-7, ubuntu-toolchain-r-test]
+          packages: [clang++-7, libc++-dev]
+      env: COMPILER=clang++-7 CXXSTD=11
+    - &clang-8
+      compiler: clang
       addons:
         apt:
-          sources:
-             - llvm-toolchain-precise-3.6
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-3.6
-             - libc++-dev
-      env: COMPILER=clang++-3.6 CXXSTD=14
-    - compiler: clang
-      addons:
-        apt:
-          sources:
-             - llvm-toolchain-precise-3.7
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-3.7
-             - libc++-dev
-      env: COMPILER=clang++-3.7 CXXSTD=14
-    - compiler: clang
+          sources: [llvm-toolchain-xenial-8, ubuntu-toolchain-r-test]
+          packages: [clang++-8, libc++-dev]
+      env: COMPILER=clang++-8 CXXSTD=11
+    - &clang-9
+      compiler: clang
       addons:
         apt:
           sources:
-             - llvm-toolchain-precise-3.8
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-3.8
-             - libc++-dev
-      env: COMPILER=clang++-3.8 CXXSTD=14
-    - compiler: clang
-      addons:
-        apt:
-          sources:
-            - sourceline: "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-3.9 main"
-              key_url: "http://apt.llvm.org/llvm-snapshot.gpg.key"
+            - <<: *xenial-clang
+              sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main'
             - ubuntu-toolchain-r-test
-          packages:
-            - clang++-3.9
-            - libc++-dev
-      env: COMPILER=clang++-3.9 CXXSTD=14
-    - compiler: clang
-      addons:
-        apt:
-          sources:
-             - llvm-toolchain-xenial-4.0
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-4.0
-             - libc++-dev
-      env: COMPILER=clang++-4.0 CXXSTD=14
-    - compiler: clang
-      addons:
-        apt:
-          sources:
-             - llvm-toolchain-xenial-5.0
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-5.0
-             - libc++-dev
-      env: COMPILER=clang++-5.0 CXXSTD=14
-    - compiler: clang
-      addons:
-        apt:
-          sources:
-             - llvm-toolchain-xenial-6.0
-             - ubuntu-toolchain-r-test
-          packages:
-             - clang++-6.0
-             - libc++-dev
-      env: COMPILER=clang++-6.0 CXXSTD=14
+          packages: [clang++-9, libc++-dev]
+      env: COMPILER=clang++-9 CXXSTD=11
+    - { <<: *gcc-5, env: COMPILER=g++-5 CXXSTD=14 }
+    - { <<: *gcc-6, env: COMPILER=g++-6 CXXSTD=14 }
+    - { <<: *gcc-7, env: COMPILER=g++-7 CXXSTD=14 }
+    - { <<: *gcc-8, env: COMPILER=g++-8 CXXSTD=14 }
+    - { <<: *gcc-9, env: COMPILER=g++-9 CXXSTD=14 }
+    - { <<: *gcc-7, env: COMPILER=g++-7 CXXSTD=17 }
+    - { <<: *gcc-8, env: COMPILER=g++-8 CXXSTD=17 }
+    - { <<: *gcc-9, env: COMPILER=g++-9 CXXSTD=17 }
+    - { <<: *clang-35, env: COMPILER=clang++-3.5 CXXSTD=14 }
+    - { <<: *clang-36, env: COMPILER=clang++-3.6 CXXSTD=14 }
+    - { <<: *clang-37, env: COMPILER=clang++-3.7 CXXSTD=14 }
+    - { <<: *clang-38, env: COMPILER=clang++-3.8 CXXSTD=14 }
+    - { <<: *clang-39, env: COMPILER=clang++-3.9 CXXSTD=14 }
+    - { <<: *clang-4, env: COMPILER=clang++-4.0 CXXSTD=14 }
+    - { <<: *clang-5, env: COMPILER=clang++-5.0 CXXSTD=14 }
+    - { <<: *clang-6, env: COMPILER=clang++-6.0 CXXSTD=14 }
+    - { <<: *clang-7, env: COMPILER=clang++-7 CXXSTD=14 }
+    - { <<: *clang-8, env: COMPILER=clang++-8 CXXSTD=14 }
+    - { <<: *clang-9, env: COMPILER=clang++-9 CXXSTD=14 }
+    - { <<: *clang-5, env: COMPILER=clang++-5.0 CXXSTD=17 }
+    - { <<: *clang-6, env: COMPILER=clang++-6.0 CXXSTD=17 }
+    - { <<: *clang-7, env: COMPILER=clang++-7 CXXSTD=17 }
+    - { <<: *clang-8, env: COMPILER=clang++-8 CXXSTD=17 }
+    - { <<: *clang-9, env: COMPILER=clang++-9 CXXSTD=17 }
+
+before_install:
+  - sudo apt update
+  - sudo apt install -y apt-transport-https ca-certificates gnupg software-properties-common 
+  - curl -L https://apt.kitware.com/keys/kitware-archive-latest.asc | sudo apt-key add -
+  - sudo apt-add-repository 'deb https://apt.kitware.com/ubuntu/ xenial main' 
+  - sudo apt update
 
 install:
-    - if [ "$CXX" = "clang++" ]; then export CXX="$COMPILER -stdlib=libc++"; fi
-    - if [ "$CXX" = "g++" ]; then export CXX="$COMPILER"; fi
+  - sudo apt install -y cmake
 
-script: mkdir build && cd build && cmake -DCXXSTD=$CXXSTD .. && make && ./tests
+script:
+  - /usr/bin/cmake -B build -S . "-DCMAKE_CXX_STANDARD=$CXXSTD" "-DCMAKE_CXX_COMPILER=$COMPILER"
+  - /usr/bin/cmake --build build
+  - /usr/bin/cmake --build build --target test