CI fixes (#1744)

* Fix warning that not including a cmake source or build dir will be a fatal error (it is now on newest CMakes)
    * Fixes appveyor
* Travis uses CMake 3.9 for more than a year now
* Travis dropped sudo: false in December
* Dropping Sphinx 2
- clang7: Suppress self-assign warnings; fix missing virtual dtors
- pypy:
  - Keep old version (newer stuff breaks)
  - Pin packages to extra index for speed
- travis:
  - Make docker explicit; remove docker if not needed
  - Make commands more verbose (for debugging / repro)
  - Make Ubuntu dist explicit per job
- Fix Windows
- Add names to travis
diff --git a/.appveyor.yml b/.appveyor.yml
index 0eb6aa5..79a5916 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -62,6 +62,7 @@
     -DPYBIND11_WERROR=ON
     -DDOWNLOAD_CATCH=ON
     -DCMAKE_SUPPRESS_REGENERATION=1
+    .
 - set MSBuildLogger="C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
 - cmake --build . --config %CONFIG% --target pytest -- /m /v:m /logger:%MSBuildLogger%
 - cmake --build . --config %CONFIG% --target cpptest -- /m /v:m /logger:%MSBuildLogger%
diff --git a/.travis.yml b/.travis.yml
index d7f300e..e1209b6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,4 @@
 language: cpp
-dist: trusty
-sudo: false
 matrix:
   include:
   # This config does a few things:
@@ -11,14 +9,14 @@
   #   also tests the automatic discovery functions in CMake (Python version, C++ standard).
   - os: linux
     dist: xenial # Necessary to run doxygen 1.8.15
-    env: STYLE DOCS PIP
+    name: Style, docs, and pip
     cache: false
     before_install:
     - pyenv global $(pyenv whence 2to3)  # activate all python versions
     - PY_CMD=python3
     - $PY_CMD -m pip install --user --upgrade pip wheel setuptools
-    install:
-    - $PY_CMD -m pip install --user --upgrade sphinx sphinx_rtd_theme breathe flake8 pep8-naming pytest
+    install: # Breathe does not yet support Sphinx 2
+    - $PY_CMD -m pip install --user --upgrade "sphinx<2" sphinx_rtd_theme breathe flake8 pep8-naming pytest
     - curl -fsSL https://sourceforge.net/projects/doxygen/files/rel-1.8.15/doxygen-1.8.15.linux.bin.tar.gz/download | tar xz
     - export PATH="$PWD/doxygen-1.8.15/bin:$PATH"
     script:
@@ -33,62 +31,119 @@
       diff -rq $installed ./include/pybind11
     - |
       # Barebones build
-      cmake -DCMAKE_BUILD_TYPE=Debug -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON -DPYTHON_EXECUTABLE=$(which $PY_CMD)
+      cmake -DCMAKE_BUILD_TYPE=Debug -DPYBIND11_WERROR=ON -DDOWNLOAD_CATCH=ON -DPYTHON_EXECUTABLE=$(which $PY_CMD) .
       make pytest -j 2
       make cpptest -j 2
   # The following are regular test configurations, including optional dependencies.
   # With regard to each other they differ in Python version, C++ standard and compiler.
   - os: linux
+    dist: trusty
+    name: Python 2.7, c++11, gcc 4.8
     env: PYTHON=2.7 CPP=11 GCC=4.8
     addons:
       apt:
-        packages: [cmake=2.\*, cmake-data=2.\*]
+        packages:
+          - cmake=2.\*
+          - cmake-data=2.\*
   - os: linux
+    dist: trusty
+    name: Python 3.6, c++11, gcc 4.8
     env: PYTHON=3.6 CPP=11 GCC=4.8
     addons:
       apt:
-        sources: [deadsnakes]
-        packages: [python3.6-dev python3.6-venv, cmake=2.\*, cmake-data=2.\*]
-  - sudo: true
-    services: docker
-    env: PYTHON=2.7 CPP=14 GCC=6 CMAKE=1
-  - sudo: true
-    services: docker
-    env: PYTHON=3.5 CPP=14 GCC=6 DEBUG=1
-  - sudo: true
-    services: docker
-    env: PYTHON=3.6 CPP=17 GCC=7
+        sources:
+          - deadsnakes
+        packages:
+          - python3.6-dev
+          - python3.6-venv
+          - cmake=2.\*
+          - cmake-data=2.\*
   - os: linux
-    env: PYTHON=3.6 CPP=17 CLANG=5.0
+    dist: trusty
+    env: PYTHON=2.7 CPP=14 GCC=6 CMAKE=1
+    name: Python 2.7, c++14, gcc 4.8, CMake test
     addons:
       apt:
-        sources: [deadsnakes, llvm-toolchain-trusty-5.0, ubuntu-toolchain-r-test]
-        packages: [python3.6-dev python3.6-venv clang-5.0 llvm-5.0-dev, lld-5.0]
+        sources:
+          - ubuntu-toolchain-r-test
+        packages:
+          - g++-6
+  - os: linux
+    dist: trusty
+    name: Python 3.5, c++14, gcc 6, Debug build
+    # N.B. `ensurepip` could be installed transitively by `python3.5-venv`, but
+    # seems to have apt conflicts (at least for Trusty). Use Docker instead.
+    services: docker
+    env: DOCKER=debian:stretch PYTHON=3.5 CPP=14 GCC=6 DEBUG=1
+  - os: linux
+    dist: xenial
+    env: PYTHON=3.6 CPP=17 GCC=7
+    name: Python 3.6, c++17, gcc 7
+    addons:
+      apt:
+        sources:
+          - deadsnakes
+          - ubuntu-toolchain-r-test
+        packages:
+          - g++-7
+          - python3.6-dev
+          - python3.6-venv
+  - os: linux
+    dist: xenial
+    env: PYTHON=3.6 CPP=17 CLANG=7
+    name: Python 3.6, c++17, Clang 7
+    addons:
+      apt:
+        sources:
+          - deadsnakes
+          - llvm-toolchain-xenial-7
+        packages:
+          - python3.6-dev
+          - python3.6-venv
+          - clang-7
+          - libclang-7-dev
+          - llvm-7-dev
+          - lld-7
+          - libc++-7-dev
+          - libc++abi-7-dev  # Why is this necessary???
   - os: osx
+    name: Python 2.7, c++14, AppleClang 7.3, CMake test
     osx_image: xcode7.3
     env: PYTHON=2.7 CPP=14 CLANG CMAKE=1
   - os: osx
+    name: Python 3.7, c++14, AppleClang 9, Debug build
     osx_image: xcode9
     env: PYTHON=3.7 CPP=14 CLANG DEBUG=1
   # Test a PyPy 2.7 build
   - os: linux
+    dist: trusty
     env: PYPY=5.8 PYTHON=2.7 CPP=11 GCC=4.8
+    name: PyPy 5.8, Python 2.7, c++11, gcc 4.8
     addons:
       apt:
-        packages: [libblas-dev, liblapack-dev, gfortran]
+        packages:
+          - libblas-dev
+          - liblapack-dev
+          - gfortran
   # Build in 32-bit mode and tests against the CMake-installed version
-  - sudo: true
+  - os: linux
+    dist: trusty
     services: docker
-    env: ARCH=i386 PYTHON=3.5 CPP=14 GCC=6 INSTALL=1
+    env: DOCKER=i386/debian:stretch PYTHON=3.5 CPP=14 GCC=6 INSTALL=1
+    name: Python 3.4, c++14, gcc 6, 32-bit
     script:
       - |
-        $SCRIPT_RUN_PREFIX sh -c "set -e
-        cmake ${CMAKE_EXTRA_ARGS} -DPYBIND11_INSTALL=1 -DPYBIND11_TEST=0
-        make install
-        cp -a tests /pybind11-tests
-        mkdir /build-tests && cd /build-tests
-        cmake ../pybind11-tests ${CMAKE_EXTRA_ARGS} -DPYBIND11_WERROR=ON
-        make pytest -j 2"
+        # Consolidated 32-bit Docker Build + Install
+        set -ex
+        $SCRIPT_RUN_PREFIX sh -c "
+          set -ex
+          cmake ${CMAKE_EXTRA_ARGS} -DPYBIND11_INSTALL=1 -DPYBIND11_TEST=0 .
+          make install
+          cp -a tests /pybind11-tests
+          mkdir /build-tests && cd /build-tests
+          cmake ../pybind11-tests ${CMAKE_EXTRA_ARGS} -DPYBIND11_WERROR=ON
+          make pytest -j 2"
+        set +ex
 cache:
   directories:
   - $HOME/.local/bin
@@ -98,6 +153,7 @@
 before_install:
 - |
   # Configure build variables
+  set -ex
   if [ "$TRAVIS_OS_NAME" = "linux" ]; then
     if [ -n "$CLANG" ]; then
       export CXX=clang++-$CLANG CC=clang-$CLANG
@@ -108,18 +164,16 @@
       fi
       export CXX=g++-$GCC CC=gcc-$GCC
     fi
-    if [ "$GCC" = "6" ]; then DOCKER=${ARCH:+$ARCH/}debian:stretch
-    elif [ "$GCC" = "7" ]; then DOCKER=debian:buster EXTRA_PACKAGES+=" catch python3-distutils" DOWNLOAD_CATCH=OFF
-    fi
   elif [ "$TRAVIS_OS_NAME" = "osx" ]; then
     export CXX=clang++ CC=clang;
   fi
   if [ -n "$CPP" ]; then CPP=-std=c++$CPP; fi
   if [ "${PYTHON:0:1}" = "3" ]; then PY=3; fi
   if [ -n "$DEBUG" ]; then CMAKE_EXTRA_ARGS+=" -DCMAKE_BUILD_TYPE=Debug"; fi
+  set +ex
 - |
   # Initialize environment
-  set -e
+  set -ex
   if [ -n "$DOCKER" ]; then
     docker pull $DOCKER
 
@@ -148,13 +202,15 @@
     if [ "$PY" = 3 ] || [ -n "$PYPY" ]; then
       $PY_CMD -m ensurepip --user
     fi
+    $PY_CMD --version
     $PY_CMD -m pip install --user --upgrade pip wheel
   fi
-  set +e
+  set +ex
 install:
 - |
   # Install dependencies
-  set -e
+  set -ex
+  cmake --version
   if [ -n "$DOCKER" ]; then
     if [ -n "$DEBUG" ]; then
       PY_DEBUG="python$PYTHON-dbg python$PY-scipy-dbg"
@@ -166,32 +222,21 @@
         libeigen3-dev libboost-dev cmake make ${EXTRA_PACKAGES} && break; done"
   else
 
-    if [ "$CLANG" = "5.0" ]; then
-      if ! [ -d ~/.local/include/c++/v1 ]; then
-        # Neither debian nor llvm provide a libc++ 5.0 deb; luckily it's fairly quick
-        # to build, install (and cache), so do it ourselves:
-        git clone --depth=1 https://github.com/llvm-mirror/llvm.git llvm-source
-        git clone https://github.com/llvm-mirror/libcxx.git llvm-source/projects/libcxx -b release_50
-        git clone https://github.com/llvm-mirror/libcxxabi.git llvm-source/projects/libcxxabi -b release_50
-        mkdir llvm-build && cd llvm-build
-        # Building llvm requires a newer cmake than is provided by the trusty container:
-        CMAKE_VER=cmake-3.8.0-Linux-x86_64
-        curl https://cmake.org/files/v3.8/$CMAKE_VER.tar.gz | tar xz
-        ./$CMAKE_VER/bin/cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=~/.local ../llvm-source
-        make -j2 install-cxxabi install-cxx
-        cp -a include/c++/v1/*cxxabi*.h ~/.local/include/c++/v1
-        cd ..
-      fi
-      export CXXFLAGS="-isystem $HOME/.local/include/c++/v1 -stdlib=libc++"
-      export LDFLAGS="-L$HOME/.local/lib -fuse-ld=lld-$CLANG"
-      export LD_LIBRARY_PATH="$HOME/.local/lib${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}"
-      if [ "$CPP" = "-std=c++17" ]; then CPP="-std=c++1z"; fi
+    if [ "$CLANG" = "7" ]; then
+      export CXXFLAGS="-stdlib=libc++"
     fi
 
     export NPY_NUM_BUILD_JOBS=2
     echo "Installing pytest, numpy, scipy..."
-    ${PYPY:+travis_wait 30} $PY_CMD -m pip install --user --upgrade pytest numpy scipy \
-        ${PYPY:+--extra-index-url https://imaginary.ca/trusty-pypi}
+    local PIP_CMD=""
+    if [ -n $PYPY ]; then
+      # For expediency, install only versions that are available on the extra index.
+      travis_wait 30 \
+        $PY_CMD -m pip install --user --upgrade --extra-index-url https://imaginary.ca/trusty-pypi \
+          pytest numpy==1.15.4 scipy==1.2.0
+    else
+      $PY_CMD -m pip install --user --upgrade pytest numpy scipy
+    fi
     echo "done."
 
     mkdir eigen
@@ -199,16 +244,37 @@
         tar --extract -j --directory=eigen --strip-components=1
     export CMAKE_INCLUDE_PATH="${CMAKE_INCLUDE_PATH:+$CMAKE_INCLUDE_PATH:}$PWD/eigen"
   fi
-  set +e
+  set +ex
 script:
-- $SCRIPT_RUN_PREFIX cmake ${CMAKE_EXTRA_ARGS}
-    -DPYBIND11_PYTHON_VERSION=$PYTHON
-    -DPYBIND11_CPP_STANDARD=$CPP
-    -DPYBIND11_WERROR=${WERROR:-ON}
-    -DDOWNLOAD_CATCH=${DOWNLOAD_CATCH:-ON}
-- $SCRIPT_RUN_PREFIX make pytest -j 2
-- $SCRIPT_RUN_PREFIX make cpptest -j 2
-- if [ -n "$CMAKE" ]; then $SCRIPT_RUN_PREFIX make test_cmake_build; fi
+- |
+  # CMake Configuration
+  set -ex
+  $SCRIPT_RUN_PREFIX cmake ${CMAKE_EXTRA_ARGS} \
+    -DPYBIND11_PYTHON_VERSION=$PYTHON \
+    -DPYBIND11_CPP_STANDARD=$CPP \
+    -DPYBIND11_WERROR=${WERROR:-ON} \
+    -DDOWNLOAD_CATCH=${DOWNLOAD_CATCH:-ON} \
+    .
+  set +ex
+- |
+  # pytest
+  set -ex
+  $SCRIPT_RUN_PREFIX make pytest -j 2 VERBOSE=1
+  set +ex
+- |
+  # cpptest
+  set -ex
+  $SCRIPT_RUN_PREFIX make cpptest -j 2
+  set +ex
+- |
+  # CMake Build Interface
+  set -ex
+  if [ -n "$CMAKE" ]; then $SCRIPT_RUN_PREFIX make test_cmake_build; fi
+  set +ex
 after_failure: cat tests/test_cmake_build/*.log*
 after_script:
-- if [ -n "$DOCKER" ]; then docker stop "$containerid"; docker rm "$containerid"; fi
+- |
+  # Cleanup (Docker)
+  set -ex
+  if [ -n "$DOCKER" ]; then docker stop "$containerid"; docker rm "$containerid"; fi
+  set +ex
diff --git a/include/pybind11/numpy.h b/include/pybind11/numpy.h
index 37471d8..ca954f5 100644
--- a/include/pybind11/numpy.h
+++ b/include/pybind11/numpy.h
@@ -1509,7 +1509,7 @@
         if (trivial == broadcast_trivial::f_trivial) result = array_t<Return, array::f_style>(shape);
         else result = array_t<Return>(shape);
 
-        if (size == 0) return result;
+        if (size == 0) return std::move(result);
 
         /* Call the function */
         if (trivial == broadcast_trivial::non_trivial)
@@ -1517,7 +1517,7 @@
         else
             apply_trivial(buffers, params, result.mutable_data(), size, i_seq, vi_seq, bi_seq);
 
-        return result;
+        return std::move(result);
     }
 
     template <size_t... Index, size_t... VIndex, size_t... BIndex>
diff --git a/tests/test_gil_scoped.cpp b/tests/test_gil_scoped.cpp
index a94b7a2..cb0010e 100644
--- a/tests/test_gil_scoped.cpp
+++ b/tests/test_gil_scoped.cpp
@@ -13,6 +13,7 @@
 
 class VirtClass  {
 public:
+    virtual ~VirtClass() {}
     virtual void virtual_func() {}
     virtual void pure_virtual_func() = 0;
 };
diff --git a/tests/test_kwargs_and_defaults.cpp b/tests/test_kwargs_and_defaults.cpp
index 2263b6b..6563fb9 100644
--- a/tests/test_kwargs_and_defaults.cpp
+++ b/tests/test_kwargs_and_defaults.cpp
@@ -34,7 +34,9 @@
     m.def("kw_func_udl_z", kw_func, "x"_a, "y"_a=0);
 
     // test_args_and_kwargs
-    m.def("args_function", [](py::args args) -> py::tuple { return args; });
+    m.def("args_function", [](py::args args) -> py::tuple {
+        return std::move(args);
+    });
     m.def("args_kwargs_function", [](py::args args, py::kwargs kwargs) {
         return py::make_tuple(args, kwargs);
     });
diff --git a/tests/test_operator_overloading.cpp b/tests/test_operator_overloading.cpp
index 4ad34d1..8ca7d8b 100644
--- a/tests/test_operator_overloading.cpp
+++ b/tests/test_operator_overloading.cpp
@@ -62,6 +62,25 @@
     };
 }
 
+// MSVC warns about unknown pragmas, and warnings are errors.
+#ifndef _MSC_VER
+  #pragma GCC diagnostic push
+  // clang 7.0.0 and Apple LLVM 10.0.1 introduce `-Wself-assign-overloaded` to
+  // `-Wall`, which is used here for overloading (e.g. `py::self += py::self `).
+  // Here, we suppress the warning using `#pragma diagnostic`.
+  // Taken from: https://github.com/RobotLocomotion/drake/commit/aaf84b46
+  // TODO(eric): This could be resolved using a function / functor (e.g. `py::self()`).
+  #if (__APPLE__) && (__clang__)
+    #if (__clang_major__ >= 10) && (__clang_minor__ >= 0) && (__clang_patchlevel__ >= 1)
+      #pragma GCC diagnostic ignored "-Wself-assign-overloaded"
+    #endif
+  #elif (__clang__)
+    #if (__clang_major__ >= 7)
+      #pragma GCC diagnostic ignored "-Wself-assign-overloaded"
+    #endif
+  #endif
+#endif
+
 TEST_SUBMODULE(operators, m) {
 
     // test_operator_overloading
@@ -144,3 +163,7 @@
         .def_readwrite("b", &NestC::b);
     m.def("get_NestC", [](const NestC &c) { return c.value; });
 }
+
+#ifndef _MSC_VER
+  #pragma GCC diagnostic pop
+#endif
diff --git a/tests/test_smart_ptr.cpp b/tests/test_smart_ptr.cpp
index 5f1fd07..87c9be8 100644
--- a/tests/test_smart_ptr.cpp
+++ b/tests/test_smart_ptr.cpp
@@ -336,7 +336,9 @@
 
     // test_shared_ptr_gc
     // #187: issue involving std::shared_ptr<> return value policy & garbage collection
-    struct ElementBase { virtual void foo() { } /* Force creation of virtual table */ };
+    struct ElementBase {
+        virtual ~ElementBase() { } /* Force creation of virtual table */
+    };
     py::class_<ElementBase, std::shared_ptr<ElementBase>>(m, "ElementBase");
 
     struct ElementA : ElementBase {
diff --git a/tests/test_virtual_functions.cpp b/tests/test_virtual_functions.cpp
index c9a561c..ccf018d 100644
--- a/tests/test_virtual_functions.cpp
+++ b/tests/test_virtual_functions.cpp
@@ -129,6 +129,7 @@
 
 class NCVirt {
 public:
+    virtual ~NCVirt() { }
     virtual NonCopyable get_noncopyable(int a, int b) { return NonCopyable(a, b); }
     virtual Movable get_movable(int a, int b) = 0;