From c06f4f43015528db45bd6b44b46c057d88b38583 Mon Sep 17 00:00:00 2001
From: Chris Eibl <138194463+chris-eibl@users.noreply.github.com>
Date: Thu, 19 Feb 2026 13:38:46 +0100
Subject: [PATCH] GH-144679: When building with VS 2026 on Windows, use
 PlatformToolset v145 by default (GH-144680)

---
 .../next/Build/2026-02-10-18-26-04.gh-issue-144679.FIH73W.rst   | 2 ++
 PCbuild/python.props                                            | 2 +-
 PCbuild/pythoncore.vcxproj                                      | 2 +-
 Tools/msi/bundle/bootstrap/pythonba.vcxproj                     | 1 +
 4 files changed, 5 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Build/2026-02-10-18-26-04.gh-issue-144679.FIH73W.rst

diff --git a/Misc/NEWS.d/next/Build/2026-02-10-18-26-04.gh-issue-144679.FIH73W.rst b/Misc/NEWS.d/next/Build/2026-02-10-18-26-04.gh-issue-144679.FIH73W.rst
new file mode 100644
index 00000000000..ebcfda54da3
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2026-02-10-18-26-04.gh-issue-144679.FIH73W.rst
@@ -0,0 +1,2 @@
+When building with Visual Studio 2026 (Version 18), use PlatformToolSet v145
+by default. Patch by Chris Eibl.
diff --git a/PCbuild/python.props b/PCbuild/python.props
index 82e6365bb39..3ad8d81dfc9 100644
--- a/PCbuild/python.props
+++ b/PCbuild/python.props
@@ -11,7 +11,7 @@
 
     We set BasePlatformToolset for ICC's benefit, it's otherwise ignored.
     -->
-    <BasePlatformToolset Condition="'$(BasePlatformToolset)' == '' and '$(VisualStudioVersion)' == '18.0'">v143</BasePlatformToolset>
+    <BasePlatformToolset Condition="'$(BasePlatformToolset)' == '' and '$(VisualStudioVersion)' == '18.0'">v145</BasePlatformToolset>
     <BasePlatformToolset Condition="'$(BasePlatformToolset)' == '' and '$(VisualStudioVersion)' == '17.0'">v143</BasePlatformToolset>
     <BasePlatformToolset Condition="'$(BasePlatformToolset)' == '' and '$(VisualStudioVersion)' == '16.0'">v142</BasePlatformToolset>
     <BasePlatformToolset Condition="'$(BasePlatformToolset)' == '' and ('$(MSBuildToolsVersion)' == '15.0' or '$(VisualStudioVersion)' == '15.0')">v141</BasePlatformToolset>
diff --git a/PCbuild/pythoncore.vcxproj b/PCbuild/pythoncore.vcxproj
index 5e37dd33c84..61bee29c0af 100644
--- a/PCbuild/pythoncore.vcxproj
+++ b/PCbuild/pythoncore.vcxproj
@@ -730,7 +730,7 @@
       </ClCompile>
     </ItemGroup>
   </Target>
-  <Target Name="_WarnAboutToolset" BeforeTargets="PrepareForBuild" Condition="$(PlatformToolset) != 'v141' and $(PlatformToolset) != 'v142' and $(PlatformToolset) != 'v143'">
+  <Target Name="_WarnAboutToolset" BeforeTargets="PrepareForBuild" Condition="$(PlatformToolset) != 'v143' and $(PlatformToolset) != 'v145'">
     <Warning Text="Toolset $(PlatformToolset) is not used for official builds. Your build may have errors or incompatibilities." />
   </Target>
   <Target Name="_WarnAboutZlib" BeforeTargets="PrepareForBuild" Condition="!$(IncludeExternals)">
diff --git a/Tools/msi/bundle/bootstrap/pythonba.vcxproj b/Tools/msi/bundle/bootstrap/pythonba.vcxproj
index 3970e857894..4b38582f0d3 100644
--- a/Tools/msi/bundle/bootstrap/pythonba.vcxproj
+++ b/Tools/msi/bundle/bootstrap/pythonba.vcxproj
@@ -21,6 +21,7 @@
   <PropertyGroup Label="Globals">
     <Configuration Condition="'$(Configuration)' == ''">Release</Configuration>
     <Platform Condition="'$(Platform)' == ''">Win32</Platform>
+    <PlatformToolset Condition="'$(PlatformToolset)' == '' and '$(VisualStudioVersion)' == '18.0'">v145</PlatformToolset>
     <PlatformToolset Condition="'$(PlatformToolset)' == '' and '$(VisualStudioVersion)' == '17.0'">v143</PlatformToolset>
     <PlatformToolset Condition="'$(PlatformToolset)' == '' and '$(VisualStudioVersion)' == '16.0'">v142</PlatformToolset>
     <PlatformToolset Condition="'$(PlatformToolset)' == '' and ('$(MSBuildToolsVersion)' == '15.0' or '$(VisualStudioVersion)' == '15.0')">v141</PlatformToolset>