Patch VS installation reference on Windows

Patch VS installation reference on Windows

Author: tothambrus11

.github/workflows/llvm-binaries.yml

@@ -380,6 +380,13 @@ jobs:
       - name: Install LLVM
         run: cmake --build ${{ github.workspace }}/BinaryCache/1 --target ${{ matrix.install_target }}
 
+      - name: Patch VS path in LLVMExports.cmake (Windows only)
+        if: ${{ matrix.os == 'windows-2025' }}
+        shell: pwsh
+        working-directory: ${{ github.workspace }}/BuildRoot/${{ env.PACKAGE_NAME }}
+        run: |
+          pwsh -File ${{ github.workspace }}/SourceCache/llvm-build/scripts/fix-vs.ps1
+
       - name: Package LLVM
         working-directory: ${{ github.workspace }}/BuildRoot/
         run: >-

README.md

@@ -19,3 +19,5 @@ Swift compatibility is mostly irrelevant except when it comes to
 Windows, where these builds of LLVM always link against a release-mode
 multithreaded DLL C runtime and have iterator debugging disabled
 (`_ITERATOR_DEBUG_LEVEL=0`) for C++.
+
+> Note: On Windows, make sure to set the environment variable `VSINSTALLDIR` to something like `C:/Program Files/Microsoft Visual Studio/2022/Community`, without `/` at the end. This is needed for LLVM to locate the DIA SDK.

scripts/README.md

@@ -2,3 +2,5 @@ The files in this directory were written for testing and diagnosing
 the functionality of this project, but they are not used by the actual
 workflow run.  Don't expect them to be accurate, portable, or anything
 else.
+
+- fix-vs.ps1: PowerShell script to patch hardcoded Visual Studio paths in LLVMExports.cmake after install (Windows only, not shipped in tarballs)

scripts/fix-vs.ps1

@@ -0,0 +1,30 @@
+# fix-vs.ps1
+# This script replaces any hardcoded Visual Studio path in LLVMExports.cmake
+# with the literal string $ENV{VSINSTALLDIR} for portability across systems.
+# Usage: Run this script in PowerShell after LLVM installation, inside the LLVM folder.
+# This is a fix for https://github.com/hylo-lang/llvm-build/issues/15 and https://discourse.llvm.org/t/llvm-assumes-specific-visual-studio-installation-after-build/79857/4
+
+# Path to the LLVMExports.cmake file (relative to LLVM install root)
+$llvmExportsPath = "./lib/cmake/llvm/LLVMExports.cmake"
+
+# Check if the LLVMExports.cmake file exists
+if (-Not (Test-Path $llvmExportsPath)) {
+    Write-Error "The file $llvmExportsPath does not exist."
+    exit 1
+}
+
+# Regex to match typical VS install paths (e.g., C:/Program Files/Microsoft Visual Studio/2022/Enterprise/)
+$vsPathPattern = "C:[\\/]Program Files[\\/]Microsoft Visual Studio[\\/]([0-9]+)[\\/]([A-Za-z]+)[\\/]"
+# Read the contents of the LLVMExports.cmake file
+$fileContent = Get-Content -Path $llvmExportsPath -Raw
+
+# Replace all matching VS paths with the literal $ENV{VSINSTALLDIR}
+$newContent = [regex]::Replace($fileContent, $vsPathPattern, '$ENV{VSINSTALLDIR}/')
+
+if ($fileContent -eq $newContent) {
+    Write-Output "No replacements were made in $llvmExportsPath."
+    exit 1
+} else {
+    Set-Content -Path $llvmExportsPath -Value $newContent
+    Write-Output "Patched $llvmExportsPath to use $ENV{VSINSTALLDIR} instead of hardcoded VS path."
+}