From 1bc563e95275b777b80fb3c5280809c9c0234757 Mon Sep 17 00:00:00 2001
From: Henry Schreiner <henryschreineriii@gmail.com>
Date: Sun, 23 Aug 2020 08:40:25 -0400
Subject: [PATCH 1/2] ci: test C++17 on MSVC 2017

---
 .github/workflows/ci.yml | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fc92101b2e..07357b6d64 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -29,21 +29,20 @@ jobs:
             python: 3.6
             arch: x64
             max-cxx-std: 17
-            args: "-DPYBIND11_FINDPYTHON=ON"
-          - runs-on: macos-latest
-            python: 3.7
-            arch: x64
-            max-cxx-std: 17
-            args: "-DPYBIND11_FINDPYTHON=ON"
+            args: >
+              -DPYBIND11_FINDPYTHON=ON
           - runs-on: windows-2016
             python: 3.7
             arch: x86
-            max-cxx-std: 14
+            max-cxx-std: 17
+            args2: >
+              -DCMAKE_CXX_FLAGS="/permissive- /EHsc /GR"
           - runs-on: windows-latest
             python: 3.6
             arch: x64
             max-cxx-std: 17
-            args: "-DPYBIND11_FINDPYTHON=ON"
+            args: >
+              -DPYBIND11_FINDPYTHON=ON
           - runs-on: windows-latest
             python: 3.7
             arch: x64
@@ -57,6 +56,8 @@ jobs:
             python: 3.9-dev
             arch: x64
             max-cxx-std: 17
+            args: >
+              -DPYBIND11_FINDPYTHON=ON
 
         exclude:
             # Currently 32bit only, and we build 64bit
@@ -92,8 +93,7 @@ jobs:
         python-version: ${{ matrix.python }}
         architecture: ${{ matrix.arch }}
 
-    - name: Setup Boost
-      if: runner.os != 'macOS'
+    - name: Setup Boost (Windows / Linux latest)
       run: echo "::set-env name=BOOST_ROOT::$BOOST_ROOT_1_72_0"
 
     - name: Update CMake
@@ -114,7 +114,6 @@ jobs:
       run: python -m pip install -r tests/requirements.txt --prefer-binary
 
     - name: Configure C++11 ${{ matrix.args }}
-      shell: bash
       run: >
         cmake -S . -B .
         -DPYBIND11_WERROR=ON
@@ -139,7 +138,6 @@ jobs:
       run: git clean -fdx
 
     - name: Configure C++${{ matrix.max-cxx-std }} ${{ matrix.args }}
-      shell: bash
       run: >
         cmake -S . -B build2
         -DPYBIND11_WERROR=ON
@@ -147,6 +145,7 @@ jobs:
         -DDOWNLOAD_EIGEN=ON
         -DCMAKE_CXX_STANDARD=${{ matrix.max-cxx-std }}
         ${{ matrix.args }}
+        ${{ matrix.args2 }}
 
     - name: Build C++${{ matrix.max-cxx-std }}
       run: cmake --build build2 -j 2

From fc439f9810b65b23a0e690d5bbcb93571ec005a8 Mon Sep 17 00:00:00 2001
From: Yannick Jadoul <yannick.jadoul@belgacom.net>
Date: Mon, 24 Aug 2020 01:23:40 +0200
Subject: [PATCH 2/2] Add note that VS2017 requires /permissive- to build in
 C++17 mode

---
 docs/basics.rst | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/docs/basics.rst b/docs/basics.rst
index 7bf4d426d3..6bb5f98222 100644
--- a/docs/basics.rst
+++ b/docs/basics.rst
@@ -35,6 +35,14 @@ Windows
 On Windows, only **Visual Studio 2015** and newer are supported since pybind11 relies
 on various C++11 language features that break older versions of Visual Studio.
 
+.. Note::
+
+    To use the C++17 in Visual Studio 2017 (MSVC 14.1), pybind11 requires the flag
+    ``/permissive-`` to be passed to the compiler `to enforce standard conformance`_. When
+    building with Visual Studio 2019, this is not strictly necessary, but still adviced.
+
+..  _`to enforce standard conformance`: https://docs.microsoft.com/en-us/cpp/build/reference/permissive-standards-conformance?view=vs-2017
+
 To compile and run the tests:
 
 .. code-block:: batch