Select the dcmqi archive by target architecture, not by host

.github/workflows/cd.yml

@@ -92,6 +92,12 @@ jobs:
             skip: "*musllinux*"
             arch: "x86_64"
 
+          # cibuildwheel's "auto" on Windows means AMD64 *and* x86, but dcmqi publishes no
+          # 32-bit binaries. The win32 wheel it produced could therefore only ever contain
+          # the 64-bit ones, so the architecture is pinned rather than probed.
+          - os: windows-latest
+            arch: "AMD64"
+
           - os: macos-14
             arch: "arm64"
 
@@ -102,6 +108,9 @@ jobs:
           - os: ubuntu-latest
             arch: "auto"
 
+          - os: windows-latest
+            arch: "auto"
+
     steps:
       - uses: actions/checkout@v7
         with:

.github/workflows/update-dcmqi.yml

@@ -84,9 +84,16 @@ jobs:
             esac
           done
 
-          # Generate dcmqiUrls.cmake
+          # Generate dcmqiUrls.cmake. This file carries data only -- the version, and one
+          # filename/checksum pair per published asset. Choosing between those assets is done
+          # by dcmqiArchive.cmake, which is hand-written and must not be emitted here: it was
+          # previously generated below, so any fix to the selection logic was silently
+          # reverted by the next run of this workflow.
           {
             echo '# Checksums computed from assets associated with the dcmqi GitHub release'
+            echo '#'
+            echo '# Generated by .github/workflows/update-dcmqi.yml -- do not edit by hand.'
+            echo '# Which of these assets a build uses is decided in dcmqiArchive.cmake.'
             echo ''
             echo "set(version \"$latest_version\")"
             echo ''
@@ -117,44 +124,6 @@ jobs:
             win_file="dcmqi-${latest_version}-win64.zip"
             echo "set(win64_filename        \"$win_file\")"
             echo "set(win64_sha256          \"${checksums[$win_file]}\")"
-            echo ''
-            echo ''
-
-            # Platform detection
-            echo 'cmake_host_system_information(RESULT is_64bit QUERY IS_64BIT)'
-            echo ''
-            echo 'set(archive "linux")'
-            echo ''
-            echo 'if(APPLE)'
-            if [ "$has_mac_split" = true ]; then
-              echo '  if(CMAKE_SYSTEM_PROCESSOR STREQUAL "arm64")'
-              echo '    set(archive "macos_arm64")'
-              echo '  else()'
-              echo '    set(archive "macos_x86_64")'
-              echo '  endif()'
-            else
-              echo '  set(archive "macos")'
-            fi
-            echo 'endif()'
-            echo ''
-            echo 'if(WIN32)'
-            echo '  if(is_64bit AND NOT (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "ARM64"))'
-            echo '    set(archive "win64")'
-            echo '  endif()'
-            echo 'endif()'
-            echo ''
-            echo 'if(NOT DEFINED "${archive}_filename")'
-            echo '  message(FATAL_ERROR "Failed to determine which archive to download: '"'"'${archive}_filename'"'"' variable is not defined")'
-            echo 'endif()'
-            echo ''
-            echo 'if(NOT DEFINED "${archive}_sha256")'
-            echo '  message(FATAL_ERROR "Could you make sure variable '"'"'${archive}_sha256'"'"' is defined ?")'
-            echo 'endif()'
-            echo ''
-            echo 'set(dcmqi_archive_filename "${${archive}_filename}")'
-            echo 'set(dcmqi_archive_sha256 "${${archive}_sha256}")'
-            echo ''
-            echo 'set(dcmqi_archive_url "https://github.com/QIICR/dcmqi/releases/download/v${version}/${dcmqi_archive_filename}")'
           } > dcmqiUrls.cmake
 
           # Update binaries.txt with discovered binary list

CMakeLists.txt

@@ -4,10 +4,12 @@
 cmake_minimum_required(VERSION 3.15...3.26)
 project(${SKBUILD_PROJECT_NAME} LANGUAGES NONE)
 
-# Set in the current scope the following variables:
+# dcmqiUrls.cmake is generated: it lists every published asset and its checksum.
+# dcmqiArchive.cmake then picks the one matching this build and sets in the current scope:
 # - dcmqi_archive_url
 # - dcmqi_archive_sha256
 include(${CMAKE_CURRENT_SOURCE_DIR}/dcmqiUrls.cmake)
+include(${CMAKE_CURRENT_SOURCE_DIR}/dcmqiArchive.cmake)
 
 #
 # Download & extract archive

dcmqiArchive.cmake

@@ -0,0 +1,99 @@
+# Selects the dcmqi release asset matching the platform and architecture being built for.
+#
+# The available assets and their checksums come from dcmqiUrls.cmake, which the update-dcmqi
+# workflow regenerates; this file holds the logic and is written by hand.
+#
+# Picking the wrong asset is silent: a mismatched archive still extracts and installs, and the
+# wheel only fails later, when a user runs a binary that cannot execute on their machine. So
+# anything short of an exact platform/architecture match is a hard error here.
+
+if(NOT DEFINED version)
+  message(FATAL_ERROR "dcmqiUrls.cmake must be included before dcmqiArchive.cmake")
+endif()
+
+# The architecture this build *targets*, which is not always the host's:
+#
+#  * Visual Studio generators carry the target in CMAKE_GENERATOR_PLATFORM, and
+#    scikit-build-core sets it from the interpreter the wheel is being built for. A 32-bit
+#    Python on a 64-bit runner therefore reports "Win32" here while the host still looks
+#    64-bit -- precisely the case that used to be mistaken for win64.
+#  * macOS cross builds set CMAKE_OSX_ARCHITECTURES (scikit-build-core derives it from
+#    ARCHFLAGS, which cibuildwheel sets).
+#
+# CMAKE_SYSTEM_PROCESSOR reports the host whenever we are not cross-compiling, so it only
+# serves as the fallback.
+set(_dcmqi_arch "${CMAKE_SYSTEM_PROCESSOR}")
+if(APPLE AND CMAKE_OSX_ARCHITECTURES)
+  list(LENGTH CMAKE_OSX_ARCHITECTURES _dcmqi_arch_count)
+  if(_dcmqi_arch_count GREATER 1)
+    message(FATAL_ERROR
+      "CMAKE_OSX_ARCHITECTURES asks for a universal build (${CMAKE_OSX_ARCHITECTURES}), but "
+      "dcmqi publishes one archive per architecture. Build a separate wheel for each.")
+  endif()
+  set(_dcmqi_arch "${CMAKE_OSX_ARCHITECTURES}")
+elseif(CMAKE_GENERATOR_PLATFORM)
+  set(_dcmqi_arch "${CMAKE_GENERATOR_PLATFORM}")
+endif()
+
+string(TOLOWER "${_dcmqi_arch}" _dcmqi_arch)
+if(_dcmqi_arch MATCHES "^(x86_64|x64|amd64)$")
+  set(_dcmqi_arch "x86_64")
+elseif(_dcmqi_arch MATCHES "^(arm64|aarch64)$")
+  set(_dcmqi_arch "arm64")
+elseif(_dcmqi_arch MATCHES "^(win32|x86|i[3-6]86)$")
+  set(_dcmqi_arch "x86")
+endif()
+
+if(APPLE)
+  set(_dcmqi_platform "macos")
+elseif(WIN32)
+  set(_dcmqi_platform "win")
+elseif(UNIX)
+  set(_dcmqi_platform "linux")
+else()
+  message(FATAL_ERROR
+    "dcmqi publishes no binary package for this operating system "
+    "(CMAKE_SYSTEM_NAME=${CMAKE_SYSTEM_NAME})")
+endif()
+
+# Asset variables are named <platform>_<arch>. The two assets whose upstream names predate
+# architecture qualification get an alias: "linux" and "win64" both mean x86_64. See
+# CPACK_SYSTEM_NAME in QIICR/dcmqi.
+set(_dcmqi_candidates "${_dcmqi_platform}_${_dcmqi_arch}")
+if(_dcmqi_platform STREQUAL "linux" AND _dcmqi_arch STREQUAL "x86_64")
+  list(APPEND _dcmqi_candidates "linux")
+elseif(_dcmqi_platform STREQUAL "win" AND _dcmqi_arch STREQUAL "x86_64")
+  list(APPEND _dcmqi_candidates "win64")
+elseif(_dcmqi_platform STREQUAL "macos")
+  # Older releases shipped a single, unqualified macOS archive; the generator still emits
+  # that name if upstream ever stops splitting by architecture.
+  list(APPEND _dcmqi_candidates "macos")
+endif()
+
+set(archive "")
+foreach(_dcmqi_candidate IN LISTS _dcmqi_candidates)
+  if(DEFINED ${_dcmqi_candidate}_filename AND DEFINED ${_dcmqi_candidate}_sha256)
+    set(archive "${_dcmqi_candidate}")
+    break()
+  endif()
+endforeach()
+
+if(NOT archive)
+  set(_dcmqi_tried "")
+  foreach(_dcmqi_candidate IN LISTS _dcmqi_candidates)
+    list(APPEND _dcmqi_tried "${_dcmqi_candidate}_filename")
+  endforeach()
+  string(REPLACE ";" ", " _dcmqi_tried "${_dcmqi_tried}")
+  message(FATAL_ERROR
+    "dcmqi v${version} publishes no binary package for ${_dcmqi_platform}/${_dcmqi_arch}, so no "
+    "wheel can be built for it. Looked in dcmqiUrls.cmake for ${_dcmqi_tried} (and a matching "
+    "_sha256). Published assets: https://github.com/QIICR/dcmqi/releases/tag/v${version}")
+endif()
+
+set(dcmqi_archive_filename "${${archive}_filename}")
+set(dcmqi_archive_sha256 "${${archive}_sha256}")
+set(dcmqi_archive_url
+  "https://github.com/QIICR/dcmqi/releases/download/v${version}/${dcmqi_archive_filename}")
+
+message(STATUS
+  "dcmqi archive for ${_dcmqi_platform}/${_dcmqi_arch}: ${dcmqi_archive_filename}")

dcmqiUrls.cmake

@@ -1,4 +1,7 @@
 # Checksums computed from assets associated with the dcmqi GitHub release
+#
+# Generated by .github/workflows/update-dcmqi.yml -- do not edit by hand.
+# Which of these assets a build uses is decided in dcmqiArchive.cmake.
 
 set(version "1.5.6")
 
@@ -13,35 +16,3 @@ set(macos_x86_64_sha256   "6678f2a60547c3a14a9f0376932217c3faee28158b6805c3b89d3
 
 set(win64_filename        "dcmqi-1.5.6-win64.zip")
 set(win64_sha256          "72f4bf6bc6b265e5843c42436267fb59a8079ca765095f218300d019f9e15e3d")
-
-
-cmake_host_system_information(RESULT is_64bit QUERY IS_64BIT)
-
-set(archive "linux")
-
-if(APPLE)
-  if(CMAKE_SYSTEM_PROCESSOR STREQUAL "arm64")
-    set(archive "macos_arm64")
-  else()
-    set(archive "macos_x86_64")
-  endif()
-endif()
-
-if(WIN32)
-  if(is_64bit AND NOT (${CMAKE_SYSTEM_PROCESSOR} STREQUAL "ARM64"))
-    set(archive "win64")
-  endif()
-endif()
-
-if(NOT DEFINED "${archive}_filename")
-  message(FATAL_ERROR "Failed to determine which archive to download: '${archive}_filename' variable is not defined")
-endif()
-
-if(NOT DEFINED "${archive}_sha256")
-  message(FATAL_ERROR "Could you make sure variable '${archive}_sha256' is defined ?")
-endif()
-
-set(dcmqi_archive_filename "${${archive}_filename}")
-set(dcmqi_archive_sha256 "${${archive}_sha256}")
-
-set(dcmqi_archive_url "https://github.com/QIICR/dcmqi/releases/download/v${version}/${dcmqi_archive_filename}")