Add more compilers to CI and increase FMT_PEDANTIC warning levels (#736)

* Add a _lot_ more warnings to FMT_PEDANTIC
Fix these warnings

* Add more compilers to CI
Fix (some) of the compiler errors with them

* Enable -Werror on CI
Increase warning level on MSVC when compiling with FMT_PEDANTIC

* Add VS 2013 and 2015 to Appveyor

* Fix Appveyor tests
Formatting

* Implement requested changes
Fix some of the MSVC warnings
Implement C++11 integer_sequence

* Reintroduce appveyor-build.py

* Remove ranges-test from tests

* Remove (some) explicit warning suppressions
Fix C++ standard setting in CI

* Remove (some) explicit warning suppressions
Fix C++ standard setting in CI

* Fix test builds with C++11

* Enable pedantic warnings on tests

* Fix warnings from edits to master

* Cleanups

* Add C++11 support to ranges.h
Re-enable ranges-test
Fix a Visual Studio error about function not returning a value in printf.h
Fix a bug in .travis.yml

.travis.yml

@@ -1,10 +1,12 @@
 language: cpp
 dist: trusty
-sudo: required # the doc target uses sudo to install dependencies
+sudo: false
+
+os: linux
+
+git:
+  depth: 1
 
-os:
-  - linux
-  - osx
 
 env:
   global:
@@ -12,18 +14,81 @@ env:
         a1eovNn4uol9won7ghr67eD3/59oeESN+G9bWE+ecI1V6yRseG9whniGhIpC/YfMW/Qz5I
         5sxSmFjaw9bxCISNwUIrL1O5x2AmRYTnFcXk4dFsUvlZg+WeF/aKyBYCNRM8C2ndbBmtAO
         o1F2EwFbiso0EmtzhAPs19ujiVxkLn4=
-  matrix:
-    - BUILD=Doc
-    - BUILD=Debug STANDARD=14
-    - BUILD=Release STANDARD=14
 
 matrix:
-  exclude:
-    - os: osx
-      env: BUILD=Doc
   include:
+      # Documentation
+    - env: BUILD=Doc
+      sudo: required
+      # g++ 6 on Linux with C++14
+    - env: COMPILER=g++-6 BUILD=Debug STANDARD=14
+      compiler: gcc
+      addons:
+        apt:
+          update: true
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - g++-6
+    - env: COMPILER=g++-6 BUILD=Release STANDARD=14
+      compiler: gcc
+      addons:
+        apt:
+          update: true
+          sources:
+            - ubuntu-toolchain-r-test
+          packages:
+            - g++-6
+      # Apple clang on OS X with C++14
+    - env: BUILD=Debug STANDARD=14
+      compiler: clang
+      os: osx
+    - env: BUILD=Release STANDARD=14
+      compiler: clang
+      os: osx
+      # clang 6.0 on Linux with C++14
+    - env: COMPILER=clang++-6.0 BUILD=Debug STANDARD=14
+      compiler: clang
+      addons:
+        apt:
+          update: true
+          packages:
+            - clang-6.0
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-trusty
+            - llvm-toolchain-trusty-6.0
+      # clang 4.0 on Linux with C++14
+    - env: COMPILER=clang++-4.0 BUILD=Debug STANDARD=11
+      compiler: clang
+      addons:
+        apt:
+          update: true
+          packages:
+            - clang-4.0
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-trusty
+            - llvm-toolchain-trusty-4.0
+      # g++ 4.8 on Linux with C++11
+    - env: COMPILER=g++-4.8 BUILD=Debug STANDARD=11
+      compiler: gcc
+      # g++ 4.4 on Linux with C++11
+    - env: COMPILER=g++-4.4 BUILD=Debug STANDARD=11
+      compiler: gcc
+      addons:
+        apt:
+          update: true
+          packages:
+            - g++-4.4
+          sources:
+            - ubuntu-toolchain-r-test
+      # Android
     - language: android
       android:
+      addons:
+        apt:
+          update: true
       components:
         - tools
         - platform-tools
@@ -51,17 +116,14 @@ matrix:
       after_success:
         - cd ${TRAVIS_BUILD_DIR}
         - tree ./libs
+  allow_failures:
+      # Errors
+    - env: COMPILER=g++-4.4 BUILD=Debug STANDARD=11
+      compiler: gcc
 
-# Install gcc-6 for extended constexpr support.
-addons:
-  apt:
-    sources:
-    - ubuntu-toolchain-r-test
-    packages:
-    - g++-6
-
-before_install:
-  - if [[ "$TRAVIS_OS_NAME" == "linux" ]]; then export CXX=g++-6; fi
+before_script:
+  - if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then export CXX=${COMPILER}; fi
+  - if [[ "${BUILD}" != "Doc" ]]; then ${CXX} --version; fi
 
 script:
   - support/travis-build.py