Ensure we use the first Python on PATH

cpp/CMakeLists.txt

@@ -140,6 +140,11 @@ include(DefineOptions)
 if(${CMAKE_VERSION} VERSION_LESS "3.12.0")
   find_package(PythonInterp)
 else()
+  # Use the first Python installation on PATH, not the newest one
+  set(Python3_FIND_STRATEGY "LOCATION")
+  # On Windows, use registry last, not first
+  set(Python3_FIND_REGISTRY "LAST")
+
   find_package(Python3)
   set(PYTHON_EXECUTABLE ${Python3_EXECUTABLE})
 endif()

cpp/cmake_modules/FindNumPy.cmake

@@ -38,7 +38,7 @@
 #
 #============================================================================
 
-if(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.14.0")
+if(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.15.0")
     # FindPython3Alt.cmake also looks for NumPy, use it.
     if(NumPy_FIND_REQUIRED)
         find_package(Python3Alt REQUIRED)
@@ -50,7 +50,7 @@ if(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.14.0")
     return()
 endif()
 
-# Legacy code below (CMake < 3.14.0)
+# Legacy code below (CMake < 3.15.0)
 
 # Finding NumPy involves calling the Python interpreter
 if(NumPy_FIND_REQUIRED)

cpp/cmake_modules/FindPython3Alt.cmake

@@ -22,7 +22,8 @@
 # - PYTHON_LIBRARIES
 # - PYTHON_OTHER_LIBS
 
-if(${CMAKE_VERSION} VERSION_LESS "3.14.0")
+# Need CMake 3.15 or later for Python3_FIND_STRATEGY
+if(${CMAKE_VERSION} VERSION_LESS "3.15.0")
   # Use deprecated FindPythonInterp package
   if(Python3Alt_FIND_REQUIRED)
     find_package(PythonLibsNew REQUIRED)

cpp/cmake_modules/FindPythonLibsNew.cmake

@@ -57,7 +57,7 @@
 # (To distribute this file outside of CMake, substitute the full
 #  License text for the above reference.)
 
-# Legacy code for CMake < 3.14.0.  The primary point of entry should be
+# Legacy code for CMake < 3.15.0.  The primary point of entry should be
 # FindPython3Alt.cmake.
 
 # Use the Python interpreter to find the libs.

python/CMakeLists.txt

@@ -18,7 +18,7 @@
 # Includes code assembled from BSD/MIT/Apache-licensed code from some 3rd-party
 # projects, including Kudu, Impala, and libdynd. See python/LICENSE.txt
 
-cmake_minimum_required(VERSION 2.7)
+cmake_minimum_required(VERSION 3.2)
 project(pyarrow)
 
 # Running from a Python sdist tarball
@@ -41,6 +41,11 @@ if(POLICY CMP0054)
   cmake_policy(SET CMP0054 NEW)
 endif()
 
+# Use the first Python installation on PATH, not the newest one
+set(Python3_FIND_STRATEGY "LOCATION")
+# On Windows, use registry last, not first
+set(Python3_FIND_REGISTRY "LAST")
+
 # Allow "make install" to not depend on all targets.
 #
 # Must be declared in the top-level CMakeLists.txt.