[llvm] workflows/release-binaries: Improve Windows installer (PR #220414)

[Saleem Abdulrasool via llvm-commits]

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@@ -419,6 +421,42 @@ exit /b 0
 
 ::=============================================================================
 
+::==============================================================================
+:: Verify that the generated MSI has LLVM's permanent UpgradeCode.
+::==============================================================================
+:verify_msi_upgrade_code
+set "expected_upgrade_code=B08613CD-8BD0-4FB6-8937-621936604DE3"
+set "msi_path="
+for %%f in (*.msi) do (
+  if defined msi_path (
+    echo Found more than one MSI in %cd%; cannot determine which one to verify.
+    exit /b 1
+  )
+  set "msi_path=%%~ff"
+)
+if not defined msi_path (
+  echo No MSI found in %cd%.
+  exit /b 1
+)
+
+set "wix_source=%TEMP%\llvm-msi-%RANDOM%.wxs"
+dark.exe -nologo -o "%wix_source%" "%msi_path%"
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compnerd wrote:

This is a bit risky - `dark` is deprecated and removed in the future versions. Can we use powershell instead to query the MSI via the MSI APIs?

https://github.com/llvm/llvm-project/pull/220414