From ca489bd4208e4a2d44b9f1d2624304b43f371c0a Mon Sep 17 00:00:00 2001
From: Dale Glass <dale@daleglass.net>
Date: Tue, 16 Feb 2021 11:46:22 +0100
Subject: [PATCH] Simplify system Qt path

---
 CMakeLists.txt | 10 ++++++----
 hifi_qt.py     | 45 +++++++++++++++++----------------------------
 prebuild.py    | 17 ++++++++++-------
 3 files changed, 33 insertions(+), 39 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5993ab8764..cf82dfdfc6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -101,11 +101,13 @@ include("${CMAKE_BINARY_DIR}/vcpkg.cmake")
 
 if (HIFI_ANDROID)
   set(QT_CMAKE_PREFIX_PATH "$ENV{HIFI_ANDROID_PRECOMPILED}/qt/lib/cmake")
-else() 
-  if(NOT EXISTS "${CMAKE_BINARY_DIR}/qt.cmake")
-      message(FATAL_ERROR "qt configuration missing.")
+else()
+  if (NOT $ENV{VIRCADIA_USE_SYSTEM_QT})
+    if(NOT EXISTS "${CMAKE_BINARY_DIR}/qt.cmake")
+        message(FATAL_ERROR "qt configuration missing.")
+    endif()
+    include("${CMAKE_BINARY_DIR}/qt.cmake")
   endif()
-  include("${CMAKE_BINARY_DIR}/qt.cmake")
 endif()
 
 option(VCPKG_APPLOCAL_DEPS OFF)
diff --git a/hifi_qt.py b/hifi_qt.py
index dbff6319ff..d11988ed2e 100644
--- a/hifi_qt.py
+++ b/hifi_qt.py
@@ -34,6 +34,7 @@ endif()
         system = platform.system()
 
         qt_found = False
+        system_qt = False
 
         # Here we handle the 3 possible cases of dealing with Qt:
         if os.getenv('VIRCADIA_USE_SYSTEM_QT'):
@@ -45,25 +46,11 @@ endif()
             if system != "Linux":
                 raise Exception("Using the system Qt is only supported on Linux")
 
-            cmake_paths = [ "lib64/cmake", "lib/cmake" ]
-            cmake_path_ok = False
-
-            # This makes the lockFile stuff happy. Needs to be writable.
-            self.path = tempfile.mkdtemp()
-
-            self.fullPath = '/usr'
-
-            # Find the cmake directory
-            for cp in cmake_paths:
-                self.cmakePath = os.path.join(self.fullPath, cp)
-                if os.path.isdir(self.cmakePath):
-                    cmake_path_ok = True
-                    break
-
-            if not cmake_path_ok:
-                raise Exception("Failed to find cmake directory. Looked under " + self.fullPath + " in " + (', '.join(cmake_paths)))
+            self.path = None
+            self.cmakePath = None
 
             qt_found = True
+            system_qt = True
             print("Using system Qt")
 
         elif os.getenv('VIRCADIA_QT_PATH'):
@@ -98,19 +85,21 @@ endif()
             qt_found = os.path.isdir(self.fullPath)
             print("Using a packaged Qt")
 
-        if qt_found:
-            # Sanity check, ensure we have a good cmake directory
-            if not os.path.isdir(os.path.join(self.cmakePath, "Qt5")):
-                raise Exception("Failed to find Qt5 directory under " + self.cmakePath)
 
-        # I'm not sure why this is needed. It's used by hifi_singleton.
-        # Perhaps it stops multiple build processes from interferring?
-        lockDir, lockName = os.path.split(self.path)
-        lockName += '.lock'
-        if not os.path.isdir(lockDir):
-            os.makedirs(lockDir)
+        if not system_qt:
+            if qt_found:
+                # Sanity check, ensure we have a good cmake directory
+                if not os.path.isdir(os.path.join(self.cmakePath, "Qt5")):
+                    raise Exception("Failed to find Qt5 directory under " + self.cmakePath)
 
-        self.lockFile = os.path.join(lockDir, lockName)
+            # I'm not sure why this is needed. It's used by hifi_singleton.
+            # Perhaps it stops multiple build processes from interferring?
+            lockDir, lockName = os.path.split(self.path)
+            lockName += '.lock'
+            if not os.path.isdir(lockDir):
+                os.makedirs(lockDir)
+
+            self.lockFile = os.path.join(lockDir, lockName)
 
         if qt_found:
             print("Found pre-built Qt5")
diff --git a/prebuild.py b/prebuild.py
index d5bed2d813..47ec01f8cc 100644
--- a/prebuild.py
+++ b/prebuild.py
@@ -130,23 +130,26 @@ def main():
         with timer('NSIS'):
             hifi_utils.downloadAndExtract(assets_url + '/dependencies/NSIS-hifi-plugins-1.0.tgz', "C:/Program Files (x86)")
 
-    qtInstallPath = ''
+    qtInstallPath = None
     # If not android, install our Qt build
     if not args.android:
         qt = hifi_qt.QtDownloader(args)
         qtInstallPath = qt.cmakePath
-        with hifi_singleton.Singleton(qt.lockFile) as lock:
-            with timer('Qt'):
-                qt.installQt()
-                qt.writeConfig()
+
+        if qtInstallPath is not None:
+            # qtInstallPath is None when we're doing a system Qt build
+            with hifi_singleton.Singleton(qt.lockFile) as lock:
+                with timer('Qt'):
+                    qt.installQt()
+                    qt.writeConfig()
 
     pm = hifi_vcpkg.VcpkgRepo(args)
-    if qtInstallPath != '':
+    if qtInstallPath is not None:
         pm.writeVar('QT_CMAKE_PREFIX_PATH', qtInstallPath)
 
     # Only allow one instance of the program to run at a time
 
-    if qtInstallPath != '':
+    if qtInstallPath is not None:
         pm.writeVar('QT_CMAKE_PREFIX_PATH', qtInstallPath)
 
     # Only allow one instance of the program to run at a time