gh-115119: Switch Windows build to mpdecimal external (GH-115182)

This includes adding what should be a relatively temporary
`Modules/_decimal/windows/mpdecimal.h` shim to choose between `mpdecimal32vc.h`
or `mpdecimal64vc.h` based on which of `CONFIG_64` or `CONFIG_32` is defined.

4 files changed, 75 insertions, 63 deletions

diff --git a/PCbuild/_decimal.vcxproj b/PCbuild/_decimal.vcxproj
index 490d7df..ee74214 100644
--- a/PCbuild/_decimal.vcxproj
+++ b/PCbuild/_decimal.vcxproj
@@ -93,51 +93,55 @@
   </PropertyGroup>
   <ItemDefinitionGroup>
     <ClCompile>
-      <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions>BUILD_LIBMPDEC;_CRT_SECURE_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(Platform)' == 'Win32'">CONFIG_32;PPRO;MASM;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(Platform)'=='ARM'">CONFIG_32;ANSI;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(Platform)'=='ARM64'">CONFIG_64;ANSI;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions Condition="'$(Platform)' == 'x64'">CONFIG_64;MASM;%(PreprocessorDefinitions)</PreprocessorDefinitions>
-      <AdditionalIncludeDirectories>..\Modules\_decimal;..\Modules\_decimal\libmpdec;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <AdditionalIncludeDirectories>..\Modules\_decimal;..\Modules\_decimal\windows;$(mpdecimalDir)\libmpdec;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
     </ClCompile>
   </ItemDefinitionGroup>
   <ItemGroup>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\basearith.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\bits.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\constants.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\convolute.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\crt.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\difradix2.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\basearith.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\bits.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\constants.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\convolute.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\crt.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\difradix2.h" />
     <ClInclude Include="..\Modules\_decimal\docstrings.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\fnt.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\fourstep.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\mpdecimal.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\numbertheory.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\sixstep.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\transpose.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\typearith.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\umodarith.h" />
-    <ClInclude Include="..\Modules\_decimal\libmpdec\vccompat.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\fnt.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\fourstep.h" />
+    <ClInclude Include="..\Modules\_decimal\windows\mpdecimal.h" />
+    <ClInclude Condition="'$(Platform)' == 'Win32'" Include="$(mpdecimalDir)\libmpdec\mpdecimal32vc.h" />
+    <ClInclude Condition="'$(Platform)' == 'ARM'" Include="$(mpdecimalDir)\libmpdec\mpdecimal32vc.h" />
+    <ClInclude Condition="'$(Platform)' == 'ARM64'" Include="$(mpdecimalDir)\libmpdec\mpdecimal64vc.h" />
+    <ClInclude Condition="'$(Platform)' == 'x64'" Include="$(mpdecimalDir)\libmpdec\mpdecimal64vc.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\numbertheory.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\sixstep.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\transpose.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\typearith.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\umodarith.h" />
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\vccompat.h" />
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\Modules\_decimal\_decimal.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\basearith.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\constants.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\context.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\convolute.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\crt.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\difradix2.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\fnt.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\fourstep.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\io.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\mpalloc.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\mpdecimal.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\numbertheory.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\sixstep.c" />
-    <ClCompile Include="..\Modules\_decimal\libmpdec\transpose.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\basearith.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\constants.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\context.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\convolute.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\crt.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\difradix2.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\fnt.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\fourstep.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\io.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\mpalloc.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\mpdecimal.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\numbertheory.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\sixstep.c" />
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\transpose.c" />
   </ItemGroup>
   <ItemGroup>
-    <CustomBuild Include="..\Modules\_decimal\libmpdec\vcdiv64.asm">
+    <CustomBuild Include="$(mpdecimalDir)\libmpdec\vcdiv64.asm">
       <ExcludedFromBuild Condition="'$(Platform)'=='Win32'">true</ExcludedFromBuild>
       <ExcludedFromBuild Condition="'$(Platform)'=='ARM'">true</ExcludedFromBuild>
       <ExcludedFromBuild Condition="'$(Platform)'=='ARM64'">true</ExcludedFromBuild>
diff --git a/PCbuild/_decimal.vcxproj.filters b/PCbuild/_decimal.vcxproj.filters
index 0cbd3d0..e4bdb64 100644
--- a/PCbuild/_decimal.vcxproj.filters
+++ b/PCbuild/_decimal.vcxproj.filters
@@ -21,49 +21,55 @@
     <ClInclude Include="..\Modules\_decimal\docstrings.h">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\basearith.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\basearith.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\bits.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\bits.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\constants.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\constants.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\convolute.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\convolute.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\crt.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\crt.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\difradix2.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\difradix2.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\fnt.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\fnt.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\fourstep.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\fourstep.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\mpdecimal.h">
+    <ClInclude Include="..\Modules\_decimal\windows\mpdecimal.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\numbertheory.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\mpdecimal32vc.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\sixstep.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\mpdecimal64vc.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\transpose.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\numbertheory.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\typearith.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\sixstep.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\umodarith.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\transpose.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
-    <ClInclude Include="..\Modules\_decimal\libmpdec\vccompat.h">
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\typearith.h">
+      <Filter>Header Files\libmpdec</Filter>
+    </ClInclude>
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\umodarith.h">
+      <Filter>Header Files\libmpdec</Filter>
+    </ClInclude>
+    <ClInclude Include="$(mpdecimalDir)\libmpdec\vccompat.h">
       <Filter>Header Files\libmpdec</Filter>
     </ClInclude>
   </ItemGroup>
@@ -71,46 +77,46 @@
     <ClCompile Include="..\Modules\_decimal\_decimal.c">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\basearith.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\basearith.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\constants.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\constants.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\context.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\context.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\convolute.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\convolute.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\crt.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\crt.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\difradix2.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\difradix2.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\fnt.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\fnt.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\fourstep.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\fourstep.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\io.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\io.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\mpalloc.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\mpalloc.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\mpdecimal.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\mpdecimal.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\numbertheory.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\numbertheory.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\sixstep.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\sixstep.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
-    <ClCompile Include="..\Modules\_decimal\libmpdec\transpose.c">
+    <ClCompile Include="$(mpdecimalDir)\libmpdec\transpose.c">
       <Filter>Source Files\libmpdec</Filter>
     </ClCompile>
   </ItemGroup>
@@ -120,8 +126,8 @@
     </ResourceCompile>
   </ItemGroup>
   <ItemGroup>
-    <CustomBuild Include="..\Modules\_decimal\libmpdec\vcdiv64.asm">
+    <CustomBuild Include="$(mpdecimalDir)\libmpdec\vcdiv64.asm">
       <Filter>Source Files\libmpdec</Filter>
     </CustomBuild>
   </ItemGroup>
-</Project>
\ No newline at end of file
+</Project>
diff --git a/PCbuild/get_externals.bat b/PCbuild/get_externals.bat
index 60ce12b..f5b7e11 100644
--- a/PCbuild/get_externals.bat
+++ b/PCbuild/get_externals.bat
@@ -54,6 +54,7 @@ set libraries=
 set libraries=%libraries%                                       bzip2-1.0.8
 if NOT "%IncludeLibffiSrc%"=="false" set libraries=%libraries%  libffi-3.4.4
 if NOT "%IncludeSSLSrc%"=="false" set libraries=%libraries%     openssl-3.0.13
+set libraries=%libraries%                                       mpdecimal-2.5.1
 set libraries=%libraries%                                       sqlite-3.45.1.0
 if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tcl-core-8.6.13.1
 if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tk-8.6.13.1
diff --git a/PCbuild/python.props b/PCbuild/python.props
index e21f1f6..a8d0807 100644
--- a/PCbuild/python.props
+++ b/PCbuild/python.props
@@ -74,6 +74,7 @@
     <libffiDir Condition="$(libffiDir) == ''">$(ExternalsDir)libffi-3.4.4\</libffiDir>
     <libffiOutDir Condition="$(libffiOutDir) == ''">$(libffiDir)$(ArchName)\</libffiOutDir>
     <libffiIncludeDir Condition="$(libffiIncludeDir) == ''">$(libffiOutDir)include</libffiIncludeDir>
+    <mpdecimalDir Condition="$(mpdecimalDir) == ''">$(ExternalsDir)\mpdecimal-2.5.1\</mpdecimalDir>
     <opensslDir Condition="$(opensslDir) == ''">$(ExternalsDir)openssl-3.0.13\</opensslDir>
     <opensslOutDir Condition="$(opensslOutDir) == ''">$(ExternalsDir)openssl-bin-3.0.13\$(ArchName)\</opensslOutDir>
     <opensslIncludeDir Condition="$(opensslIncludeDir) == ''">$(opensslOutDir)include</opensslIncludeDir>