Include `<cstdint>` in one place, remove custom typedefs

Originating from
[this SO issue](https://stackoverflow.com/questions/65901014/how-to-solve-this-all-error-2-in-this-case),
some win32 compilers define `__int32` as a `long`, but MinGW defines
`std::int32_t` as an `int`, leading to a type conflict.

To avoid this, we remove the custom `typedef` definitions for win32.  The
Tensor module requires C++11 anyways, so we are guaranteed to have
included `<cstdint>` already in `Eigen/Core`.

Also re-arranged the headers to only include `<cstdint>` in one place to
avoid this type of error again.

4 files changed, 39 insertions, 54 deletions

diff --git a/Eigen/src/Core/arch/ZVector/PacketMath.h b/Eigen/src/Core/arch/ZVector/PacketMath.h
index eb378a164..b10c1f6c7 100755
--- a/Eigen/src/Core/arch/ZVector/PacketMath.h
+++ b/Eigen/src/Core/arch/ZVector/PacketMath.h
@@ -10,8 +10,6 @@
 #ifndef EIGEN_PACKET_MATH_ZVECTOR_H
 #define EIGEN_PACKET_MATH_ZVECTOR_H
 
-#include <stdint.h>
-
 namespace Eigen {
 
 namespace internal {
@@ -51,10 +49,10 @@ typedef struct {
 #endif
 
 typedef union {
-  int32_t   i[4];
-  uint32_t ui[4];
-  int64_t   l[2];
-  uint64_t ul[2];
+  numext::int32_t   i[4];
+  numext::uint32_t ui[4];
+  numext::int64_t   l[2];
+  numext::uint64_t ul[2];
   double    d[2];
   float     f[4];
   Packet4i  v4i;
diff --git a/Eigen/src/Core/util/Meta.h b/Eigen/src/Core/util/Meta.h
index 64938d98d..ab1bc01da 100755
--- a/Eigen/src/Core/util/Meta.h
+++ b/Eigen/src/Core/util/Meta.h
@@ -25,8 +25,40 @@
 
 #endif
 
-#if EIGEN_COMP_ICC>=1600 &&  __cplusplus >= 201103L
+// Recent versions of ICC require <cstdint> for pointer types below.
+#define EIGEN_ICC_NEEDS_CSTDINT (EIGEN_COMP_ICC>=1600 && EIGEN_COMP_CXXVER >= 11)
+
+// Define portable (u)int{32,64} types
+#if EIGEN_HAS_CXX11 || EIGEN_ICC_NEEDS_CSTDINT
 #include <cstdint>
+namespace Eigen {
+namespace numext {
+typedef std::uint8_t  uint8_t;
+typedef std::int8_t   int8_t;
+typedef std::uint16_t uint16_t;
+typedef std::int16_t  int16_t;
+typedef std::uint32_t uint32_t;
+typedef std::int32_t  int32_t;
+typedef std::uint64_t uint64_t;
+typedef std::int64_t  int64_t;
+}
+}
+#else
+// Without c++11, all compilers able to compile Eigen also
+// provide the C99 stdint.h header file.
+#include <stdint.h>
+namespace Eigen {
+namespace numext {
+typedef ::uint8_t  uint8_t;
+typedef ::int8_t   int8_t;
+typedef ::uint16_t uint16_t;
+typedef ::int16_t  int16_t;
+typedef ::uint32_t uint32_t;
+typedef ::int32_t  int32_t;
+typedef ::uint64_t uint64_t;
+typedef ::int64_t  int64_t;
+}
+}
 #endif
 
 namespace Eigen {
@@ -52,13 +84,14 @@ namespace internal {
 
 // Only recent versions of ICC complain about using ptrdiff_t to hold pointers,
 // and older versions do not provide *intptr_t types.
-#if EIGEN_COMP_ICC>=1600 &&  __cplusplus >= 201103L
+#if EIGEN_ICC_NEEDS_CSTDINT
 typedef std::intptr_t  IntPtr;
 typedef std::uintptr_t UIntPtr;
 #else
 typedef std::ptrdiff_t IntPtr;
 typedef std::size_t UIntPtr;
 #endif
+#undef EIGEN_ICC_NEEDS_CSTDINT
 
 struct true_type {  enum { value = 1 }; };
 struct false_type { enum { value = 0 }; };
@@ -688,37 +721,4 @@ bool not_equal_strict(const double& x,const double& y) { return std::not_equal_t
 
 } // end namespace Eigen
 
-// Define portable (u)int{32,64} types
-#if EIGEN_HAS_CXX11
-#include <cstdint>
-namespace Eigen {
-namespace numext {
-typedef std::uint8_t  uint8_t;
-typedef std::int8_t   int8_t;
-typedef std::uint16_t uint16_t;
-typedef std::int16_t  int16_t;
-typedef std::uint32_t uint32_t;
-typedef std::int32_t  int32_t;
-typedef std::uint64_t uint64_t;
-typedef std::int64_t  int64_t;
-}
-}
-#else
-// Without c++11, all compilers able to compile Eigen also
-// provides the C99 stdint.h header file.
-#include <stdint.h>
-namespace Eigen {
-namespace numext {
-typedef ::uint8_t  uint8_t;
-typedef ::int8_t   int8_t;
-typedef ::uint16_t uint16_t;
-typedef ::int16_t  int16_t;
-typedef ::uint32_t uint32_t;
-typedef ::int32_t  int32_t;
-typedef ::uint64_t uint64_t;
-typedef ::int64_t  int64_t;
-}
-}
-#endif
-
 #endif // EIGEN_META_H
diff --git a/unsupported/Eigen/CXX11/Tensor b/unsupported/Eigen/CXX11/Tensor
index beed2308a..d73c6008d 100644
--- a/unsupported/Eigen/CXX11/Tensor
+++ b/unsupported/Eigen/CXX11/Tensor
@@ -42,18 +42,6 @@
 #include <thread>
 
 #ifdef _WIN32
-typedef __int16 int16_t;
-typedef unsigned __int16 uint16_t;
-typedef __int32 int32_t;
-typedef unsigned __int32 uint32_t;
-typedef __int64 int64_t;
-typedef unsigned __int64 uint64_t;
-#include <windows.h>
-#else
-#include <stdint.h>
-#endif
-
-#ifdef _WIN32
 #include <windows.h>
 #elif defined(__APPLE__)
 #include <mach/mach_time.h>
diff --git a/unsupported/Eigen/CXX11/ThreadPool b/unsupported/Eigen/CXX11/ThreadPool
index 71a6afe39..5f59e9714 100644
--- a/unsupported/Eigen/CXX11/ThreadPool
+++ b/unsupported/Eigen/CXX11/ThreadPool
@@ -33,7 +33,6 @@
 #if __cplusplus > 199711L || EIGEN_COMP_MSVC >= 1900
 #include <cstddef>
 #include <cstring>
-#include <stdint.h>
 #include <time.h>
 
 #include <vector>