ci: download an NSIS distribution

This avoids needing to install it on the runner host.

.gitlab/ci/download_nsis.cmake

+cmake_minimum_required(VERSION 3.12)
+
+set(nsis_url_root "https://www.paraview.org/files/dependencies")
+
+set(nsis_version "3.06.1")
+if ("$ENV{CMAKE_CONFIGURATION}" MATCHES "windows")
+  set(nsis_subdir "nsis-${nsis_version}")
+  set(sha256sum "d463ad11aa191ab5ae64edb3a439a4a4a7a3e277fcb138254317254f7111fba7")
+else ()
+  message(FATAL_ERROR
+    "Unknown platform for nsis")
+endif ()
+set(filename "${nsis_subdir}.zip")
+
+# Download the file.
+file(DOWNLOAD
+  "${nsis_url_root}/${filename}"
+  ".gitlab/${filename}"
+  STATUS download_status
+  EXPECTED_HASH "SHA256=${sha256sum}")
+
+# Check the download status.
+list(GET download_status 0 res)
+if (res)
+  list(GET download_status 1 err)
+  message(FATAL_ERROR
+    "Failed to download ${filename}: ${err}")
+endif ()
+
+# Extract the file.
+execute_process(
+  COMMAND
+    "${CMAKE_COMMAND}"
+    -E tar
+    xf "${filename}"
+  WORKING_DIRECTORY ".gitlab"
+  RESULT_VARIABLE res
+  ERROR_VARIABLE err
+  ERROR_STRIP_TRAILING_WHITESPACE)
+if (res)
+  message(FATAL_ERROR
+    "Failed to extract ${filename}: ${err}")
+endif ()
+
+# Move to a predictable prefix.
+file(RENAME
+  ".gitlab/${nsis_subdir}"
+  ".gitlab/nsis")

.gitlab/os-windows.yml

@@ -80,6 +80,8 @@
     - git submodule update --init --recursive
 
 .before_script_windows_deps: &before_script_windows_deps
+    - cmake -P .gitlab/ci/download_nsis.cmake
+    - Set-Item -Force -Path "env:PATH" -Value "$pwdpath\.gitlab\nsis;$env:PATH"
     - cmake -P .gitlab/ci/download_qt.cmake
     - Set-Item -Force -Path "env:PATH" -Value "$pwdpath\.gitlab\qt\bin;$env:PATH"
     # Add the outputs to the PATH