ci: make fat qt libs thin (#6281)

* ci: strip fat qt binaries

* parallelize

* cache thin qt

* print libs

* change qt install dir in the action

* move qt install logic to separate job

* lookup only

* debug: show contents of QTDIR

* enableCrossOsArchive also when saving

* check one dir up

* change install dir

* keep debugging

* try deleting cache

* force delete cache

* pass gh_token

* pass missing params

* use api

* change cache key, disable cross os archive

* move job directly to steps

* add comments

* set cache param directly

* address comments

* fixup

* Update .ci/thin_macos_qtlib.sh

* resolve qt version

* move resolution to separate script

* use single line for run:

* improve error handling in new scripts

---------

Co-authored-by: ebbit1q <ebbit1q@gmail.com>

.ci/compile.sh

@@ -156,6 +156,18 @@ function ccachestatsverbose() {
 
 # Compile
 if [[ $RUNNER_OS == macOS ]]; then
+  # QTDIR is needed for macOS since we actually only use the cached thin Qt binaries instead of the install-qt-action,
+  # which sets a few environment variables
+  if QTDIR=$(find "$GITHUB_WORKSPACE/Qt" -depth -maxdepth 2 -name macos -type d -print -quit); then
+    echo "found QTDIR at $QTDIR"
+  else
+    echo "could not find QTDIR!"
+    exit 2
+  fi
+  # the qtdir is located at Qt/[qtversion]/macos
+  # we use find to get the first subfolder with the name "macos"
+  # this works independent of the qt version as there should be only one version installed on the runner at a time
+  export QTDIR
 
   if [[ $TARGET_MACOS_VERSION ]]; then
     # CMAKE_OSX_DEPLOYMENT_TARGET is a vanilla cmake flag needed to compile to target macOS version

.ci/resolve_latest_aqt_qt_version.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+
+# This script is used to resolve the latest patch version of Qt using aqtinstall.
+# It interprets wildcards to get the latest patch version. E.g. "6.6.*" -> "6.6.3".
+
+# This script is meant to be used by the ci enironment.
+# It uses the runner's GITHUB_OUTPUT env variable.
+
+# Usage example: .ci/resolve_latest_aqt_qt_version.sh "6.6.*"
+
+qt_spec=$1
+if [[ ! $qt_spec ]]; then
+  echo "usage: $0 [version]"
+  exit 2
+fi
+
+# If version is already specific (no wildcard), use it as-is
+if [[ $qt_spec != *"*" ]]; then
+  echo "version $qt_spec is already resolved"
+  echo "version=$qt_spec" >> "$GITHUB_OUTPUT"
+  exit 0
+fi
+
+if ! hash aqt; then
+  echo "aqt could not be found, has aqtinstall been installed?"
+  exit 2
+fi
+
+# Resolve latest patch
+if ! qt_resolved=$(aqt list-qt mac desktop --spec "$qt_spec" --latest-version); then
+  exit 1
+fi
+
+echo "resolved $qt_spec to $qt_resolved"
+if [[ ! $qt_resolved ]]; then
+  echo "Error: Could not resolve Qt version for $qt_spec"
+  exit 1
+fi
+
+echo "version=$qt_resolved" >> "$GITHUB_OUTPUT"

.ci/thin_macos_qtlib.sh

@@ -0,0 +1,25 @@
+#!/bin/bash
+
+# The macos binaries from aqt are fat (universal), so we thin them to the target architecture to reduce the size of
+# the packages and caches using lipo.
+
+# This script is meant to be used by the ci enironment on macos runners only.
+# It uses the runner's GITHUB_WORKSPACE env variable.
+arch=$(uname -m)
+nproc=$(sysctl -n hw.ncpu)
+
+function thin() {
+  local libfile=$1
+  if [[ $(file -b --mime-type "$libfile") == application/x-mach-binary* ]]; then
+    echo "Processing $libfile"
+    lipo "$libfile" -thin "$arch" -output "$libfile"
+  fi
+  return 0
+}
+export -f thin  # export to allow use in xargs
+export arch
+set -eo pipefail
+
+echo "::group::Thinning Qt libraries to $arch using $nproc cores"
+find "$GITHUB_WORKSPACE/Qt" -type f -print0 | xargs -0 -n1 -P"$nproc" -I{} bash -c "thin '{}'"
+echo "::endgroup::"