From 46d2ba1ea4d0e5f1a2ae1d1801e416e487ea45b4 Mon Sep 17 00:00:00 2001
From: Joerg Bornemann <joerg.bornemann@qt.io>
Date: Tue, 6 Jul 2021 12:41:11 +0200
Subject: [PATCH] Restore default installation prefix from Qt 5

Change the default installation prefix to C:/Qt/Qt-${version} on Windows
and /usr/local/Qt-${version} elsewhere.

This is what's expected by users coming from Qt5, and setting the
installation prefix to "/usr/local" manually is easier than setting the
versioned variant "/usr/local/Qt-6.2.0".

[ChangeLog][Build System] The installation prefix now defaults to
/usr/local/Qt-${version} and C:/Qt/Qt-${version} like it did in Qt 5.

Fixes: QTBUG-91632
Pick-to: 6.2
Change-Id: I8ce57b1b18084c705b194c776e038cc807a6ed5e
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
---
 cmake/QtSetup.cmake | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/cmake/QtSetup.cmake b/cmake/QtSetup.cmake
index 30b3cbae677..17357dc1a46 100644
--- a/cmake/QtSetup.cmake
+++ b/cmake/QtSetup.cmake
@@ -65,13 +65,24 @@ set(CMAKE_LINK_DEPENDS_NO_SHARED ON)
 # This detection only happens when building qtbase, and later is propagated via the generated
 # QtBuildInternalsExtra.cmake file.
 if (PROJECT_NAME STREQUAL "QtBase" AND NOT QT_BUILD_STANDALONE_TESTS)
-    if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT AND FEATURE_developer_build)
-        # Handle non-prefix builds by setting the CMake install prefix to point to qtbase's build
-        # dir.
-        # While building another repo (like qtsvg) the CMAKE_PREFIX_PATH
-        # should be set on the command line to point to the qtbase build dir.
-        set(CMAKE_INSTALL_PREFIX ${QtBase_BINARY_DIR} CACHE PATH
+    if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
+        if(FEATURE_developer_build)
+            # Handle non-prefix builds by setting the CMake install prefix to point to qtbase's
+            # build dir. While building another repo (like qtsvg) the CMAKE_PREFIX_PATH should be
+            # set on the command line to point to the qtbase build dir.
+            set(__qt_default_prefix "${QtBase_BINARY_DIR}")
+        else()
+            if(CMAKE_HOST_WIN32)
+                set(__qt_default_prefix "C:/Qt/")
+            else()
+                set(__qt_default_prefix "/usr/local/")
+            endif()
+            string(APPEND __qt_default_prefix
+                "Qt-${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}.${PROJECT_VERSION_PATCH}")
+        endif()
+        set(CMAKE_INSTALL_PREFIX ${__qt_default_prefix} CACHE PATH
             "Install path prefix, prepended onto install directories." FORCE)
+        unset(__qt_default_prefix)
     endif()
     if(CMAKE_CROSSCOMPILING)
         set(__qt_prefix "${CMAKE_STAGING_PREFIX}")