From 9fbb8e0090a1d8220479e776feae7c9c5bb8493e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tor=20Arne=20Vestb=C3=B8?= <tor.arne.vestbo@qt.io>
Date: Tue, 18 Feb 2025 17:20:06 +0100
Subject: [PATCH] iOS: Set LD_ENTRY_POINT for generated Xcode project

We normally override the entrypoint to _qt_main_wrapper via the -e flag
to the linker, but if a Swift file is added to the Xcode project, Xcode
does some magic, building the app as a shared library, and wrapping it
with the Swift code into a custom executable. The -e flag will then be
a noop when linking our shared library.

To work around this we set the custom LD_ENTRY_POINT Xcode build setting,
which triggers Xcode to pass -e when linking the wrapper-executable.

This works in practice, but produces a warning on the console that the
entrypoint is not found, which has been reported as FB16519113.

Fixes: QTBUG-133577
Pick-to: 6.8
Change-Id: I9d8310b39ac5a4900693df55c2e5bfa346c0300a
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
(cherry picked from commit 430ba7c0f826ee6f91fbfdc861525cb62b8e725c)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 cmake/QtPublicAppleHelpers.cmake        | 21 +++++++++++++++++++++
 mkspecs/features/uikit/default_post.prf |  6 ++++++
 2 files changed, 27 insertions(+)

diff --git a/cmake/QtPublicAppleHelpers.cmake b/cmake/QtPublicAppleHelpers.cmake
index 7786fed8c60..9dccb10f55a 100644
--- a/cmake/QtPublicAppleHelpers.cmake
+++ b/cmake/QtPublicAppleHelpers.cmake
@@ -754,6 +754,25 @@ function(_qt_internal_set_ios_simulator_arch target)
         "x86_64")
 endfunction()
 
+function(_qt_internal_set_xcode_entrypoint_attribute target entrypoint)
+    if(CMAKE_XCODE_ATTRIBUTE_LD_ENTRY_POINT
+        OR QT_NO_SET_XCODE_LD_ENTRY_POINT)
+        return()
+    endif()
+
+    get_target_property(existing_entrypoint
+        "${target}" XCODE_ATTRIBUTE_LD_ENTRY_POINT)
+    if(NOT existing_entrypoint MATCHES "-NOTFOUND")
+        return()
+    endif()
+
+    set_target_properties("${target}"
+        PROPERTIES
+        "XCODE_ATTRIBUTE_LD_ENTRY_POINT"
+        "${entrypoint}")
+endfunction()
+
+
 # Export Apple platform sdk and xcode version requirements to Qt6ConfigExtras.cmake.
 # Always exported, even on non-Apple platforms, so that we can use them when building
 # documentation.
@@ -1022,6 +1041,8 @@ function(_qt_internal_finalize_ios_app target)
     _qt_internal_set_xcode_targeted_device_family("${target}")
     _qt_internal_set_xcode_bitcode_enablement("${target}")
     _qt_internal_set_ios_simulator_arch("${target}")
+
+    _qt_internal_set_xcode_entrypoint_attribute("${target}" "_qt_main_wrapper")
 endfunction()
 
 function(_qt_internal_finalize_macos_app target)
diff --git a/mkspecs/features/uikit/default_post.prf b/mkspecs/features/uikit/default_post.prf
index a731cd0cbe9..d330d3cdeae 100644
--- a/mkspecs/features/uikit/default_post.prf
+++ b/mkspecs/features/uikit/default_post.prf
@@ -48,6 +48,12 @@ macx-xcode {
         QMAKE_MAC_XCODE_SETTINGS += supported_platforms
     }
 
+    # Override the entry point explicitly, in case a Swift file is
+    # added to the Xcode project
+    ld_entry_point.name = LD_ENTRY_POINT
+    ld_entry_point.value = _qt_main_wrapper
+    QMAKE_MAC_XCODE_SETTINGS += ld_entry_point
+
     # In a simulator specific build the device config will set the SDK
     # to the simulator SDK, but for Xcode we always want the SDKROOT
     # to be the device SDK.