[llvm] [Github] Enable long paths in windows CI Container (PR #184224)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/184224

Otherwise we run into issues with file paths >260 characters.

https://github.com/ninja-build/ninja/issues/2400
https://gitlab.kitware.com/cmake/cmake/-/issues/22435

>From 7bae75d84ab2f47230ed5eda2112808d0dc79e76 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman at google.com>
Date: Mon, 2 Mar 2026 20:47:07 +0000
Subject: [PATCH] [Github] Enable long paths in windows CI Container

Otherwise we run into issues with file paths >260 characters.

https://github.com/ninja-build/ninja/issues/2400
https://gitlab.kitware.com/cmake/cmake/-/issues/22435
---
 .../workflows/containers/github-action-ci-windows/Dockerfile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/.github/workflows/containers/github-action-ci-windows/Dockerfile b/.github/workflows/containers/github-action-ci-windows/Dockerfile
index 508c5964bea19..f3f421a30dc49 100644
--- a/.github/workflows/containers/github-action-ci-windows/Dockerfile
+++ b/.github/workflows/containers/github-action-ci-windows/Dockerfile
@@ -89,6 +89,11 @@ RUN powershell -Command \
 RUN git config --system core.longpaths true & \
     git config --global core.autocrlf false
 
+# Enable long paths so that ninja can work with paths longer than 260 characters.
+RUN powershell -Command \
+    New-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem" \
+    -Name "LongPathsEnabled" -Value 1 -PropertyType DWORD -Force
+
 ARG RUNNER_VERSION=2.331.0
 ENV RUNNER_VERSION=$RUNNER_VERSION