Drop QT_ROOT= CLI override; derive it from QT_PATH

QT_PATH= already says "use exactly this Qt install" — QT_ROOT was
redundant once that existed. The script still uses QT_ROOT internally
(find_cmake / find_mingw look under ${QT_ROOT}/Tools), but it's now
derived from QT_PATH (two dirname levels up) instead of being a second
flag the caller has to remember.

CI invocations collapse to a single line.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: OmniTroid

.github/workflows/build.yml

@@ -42,9 +42,7 @@ jobs:
 
       - name: Configure and build
         shell: bash
-        run: |
-          QT_ROOT="$(cd "$QT_ROOT_DIR/../.." && pwd)"
-          ./configure.sh QT_ROOT="$QT_ROOT" QT_PATH="$QT_ROOT_DIR" BUILD_TYPE=Release
+        run: ./configure.sh QT_PATH="$QT_ROOT_DIR" BUILD_TYPE=Release
 
       - name: Upload Artifact
         uses: actions/upload-artifact@master
@@ -76,9 +74,7 @@ jobs:
         run: sudo apt-get update && sudo apt-get install -y ninja-build patchelf libxcb-cursor0
 
       - name: Configure and build
-        run: |
-          QT_ROOT="$(cd "$QT_ROOT_DIR/../.." && pwd)"
-          ./configure.sh QT_ROOT="$QT_ROOT" QT_PATH="$QT_ROOT_DIR" BUILD_TYPE=Release
+        run: ./configure.sh QT_PATH="$QT_ROOT_DIR" BUILD_TYPE=Release
 
       - name: Stage APNG plugin for AppImage
         run: |

configure.sh

@@ -35,8 +35,7 @@ print_help() {
     echo "Options:"
     echo "  -h, --help: Print this help message"
     echo "  clean: Remove all files from lib, bin and tmp"
-    echo "  QT_ROOT=path: Specify the root path to where Qt is installed (eg. /c/Qt/)"
-    echo "  QT_PATH=path: Specify the exact Qt install to use, bypassing auto-detection (eg. /c/Qt/6.5.3/mingw_64)"
+    echo "  QT_PATH=path: Use this Qt toolchain directly, skipping auto-detection (eg. /c/Qt/6.5.3/mingw_64)"
     echo "  BUILD_TYPE=Debug|Release: CMake build type (default: Debug)"
 }
 
@@ -378,46 +377,37 @@ configure() {
     fi
 
     # Parse KEY=VALUE overrides
-    QT_ROOT=""
     QT_PATH=""
     while [ "$#" -gt 0 ]; do
         case "$1" in
-            QT_ROOT=*) QT_ROOT="${1#*=}" ;;
             QT_PATH=*) QT_PATH="${1#*=}" ;;
             BUILD_TYPE=*) BUILD_CONFIG="${1#*=}" ;;
             *) echo "Unknown argument: $1"; print_help; exit 1 ;;
         esac
         shift
     done
 
-    # Resolve QT_ROOT (auto-detect if not overridden). Still needed even when
-    # QT_PATH is given explicitly — find_cmake / find_mingw / find_ninja use
-    # ${QT_ROOT}/Tools.
-    if [ -z "$QT_ROOT" ]; then
-        QT_ROOT=$(find_qt)
-        if [ -z "$QT_ROOT" ]; then
-            echo "Qt not found. Aborting."; exit 1;
-        fi
-    fi
-    if [ ! -d "$QT_ROOT" ]; then
-        echo "$QT_ROOT is not a directory. Aborting."
-        exit 1
-    fi
-    echo "Using Qt root: $QT_ROOT"
-
-    # Resolve QT_PATH: explicit override wins, otherwise auto-detect.
+    # Resolve QT_PATH: explicit override wins, otherwise auto-detect under $HOME/Qt.
+    # QT_ROOT is the parent of the version dir, derived from QT_PATH. Tools/ lives
+    # under it (find_cmake / find_mingw / find_ninja look there).
     if [ -n "$QT_PATH" ]; then
         if [ ! -d "$QT_PATH" ]; then
             echo "$QT_PATH is not a directory. Aborting."
             exit 1
         fi
+        QT_ROOT="$(cd "$QT_PATH/../.." && pwd)"
     else
+        QT_ROOT=$(find_qt)
+        if [ -z "$QT_ROOT" ]; then
+            echo "Qt not found. Aborting."; exit 1;
+        fi
         QT_PATH=$(find_qtpath)
         if [ -z "$QT_PATH" ] || [ ! -d "$QT_PATH" ]; then
             echo "No Qt >= ${QT_MIN_VERSION} found under ${QT_ROOT}. Aborting."
             exit 1
         fi
     fi
+    echo "Using Qt root: $QT_ROOT"
     echo "Using Qt installation: $QT_PATH"
 
     # Check for cmake, and prefer the one bundled with Qt