From 20ee9352038f961b5a9d76c986c9ae088f8ea969 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Boris=20Sch=C3=A4ling?= <boris@theboostcpplibraries.com>
Date: Sat, 28 May 2016 12:26:18 +0200
Subject: [PATCH] Use decltype to deduce return type of PyThread_create_key

---
 CMakeLists.txt              | 2 +-
 example/example10.cpp       | 2 +-
 example/example4.cpp        | 2 +-
 include/pybind11/common.h   | 2 +-
 include/pybind11/pybind11.h | 4 ++--
 5 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 510d4936d..0452d5dab 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -81,7 +81,7 @@ if(MSVC)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W4")
   endif()
 elseif ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" OR "${CMAKE_CXX_COMPILER_ID}" MATCHES "GNU")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wconversion")
 endif()
 
 
diff --git a/example/example10.cpp b/example/example10.cpp
index cbe737e72..06528c2f0 100644
--- a/example/example10.cpp
+++ b/example/example10.cpp
@@ -13,7 +13,7 @@
 
 double my_func(int x, float y, double z) {
     std::cout << "my_func(x:int=" << x << ", y:float=" << y << ", z:float=" << z << ")" << std::endl;
-    return x*y*z;
+    return (float) x*y*z;
 }
 
 std::complex<double> my_func3(std::complex<double> c) {
diff --git a/example/example4.cpp b/example/example4.cpp
index 281eafed5..7e17864e0 100644
--- a/example/example4.cpp
+++ b/example/example4.cpp
@@ -38,7 +38,7 @@ void test_function2(EMyEnumeration k) {
 
 float test_function3(int i) {
     std::cout << "test_function(" << i << ")" << std::endl;
-    return i / 2.f;
+    return (float) i / 2.f;
 }
 
 py::bytes return_bytes() {
diff --git a/include/pybind11/common.h b/include/pybind11/common.h
index 43e41d8d0..272c207e1 100644
--- a/include/pybind11/common.h
+++ b/include/pybind11/common.h
@@ -262,7 +262,7 @@ struct internals {
     std::unordered_map<const void *, void*> registered_instances;    // void * -> PyObject*
     std::unordered_set<std::pair<const PyObject *, const char *>, overload_hash> inactive_overload_cache;
 #if defined(WITH_THREAD)
-    long tstate = 0;
+    decltype(PyThread_create_key()) tstate = 0; // Usually an int but a long on Cygwin64 with Python 3.x
     PyInterpreterState *istate = nullptr;
 #endif
 };
diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index ee76a6702..46923de4c 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -1115,7 +1115,7 @@ public:
     gil_scoped_release(bool disassoc = false) : disassoc(disassoc) {
         tstate = PyEval_SaveThread();
         if (disassoc) {
-            int key = detail::get_internals().tstate;
+            auto key = detail::get_internals().tstate;
             #if PY_MAJOR_VERSION < 3
                 PyThread_delete_key_value(key);
             #else
@@ -1128,7 +1128,7 @@ public:
             return;
         PyEval_RestoreThread(tstate);
         if (disassoc) {
-            int key = detail::get_internals().tstate;
+            auto key = detail::get_internals().tstate;
             #if PY_MAJOR_VERSION < 3
                 PyThread_delete_key_value(key);
             #endif