From e1369aa7d6577d4bc787bc5743a611971052c45b Mon Sep 17 00:00:00 2001
From: Andrew Kaster <andrew@ladybird.org>
Date: Mon, 21 Apr 2025 14:57:06 -0600
Subject: [PATCH] CMake: Explicitly set CMAKE_OSX_SYSROOT to macosx for macOS
 host builds

The implicit default CMAKE_OSX_SYSROOT was a workaround in CMake for
macOS ~10.8. As of CMake 4.x, CMake expects macOS host compilers to have
their own default sysroot detection logic. However, upstream llvm does
not actually do this, only Apple Clang does. To keep supporting homebrew
clang and manually compiled clang from llvm/llvm-project, we need to
set the sysroot explicitly.

The behavior difference and lack of default detection logic in the clang
driver is tracked at https://gitlab.kitware.com/cmake/cmake/-/issues/26863
---
 CMakeLists.txt                                 | 4 ++++
 Meta/CMake/vcpkg/base-triplets/arm64-osx.cmake | 1 +
 Meta/CMake/vcpkg/base-triplets/x64-osx.cmake   | 1 +
 Meta/Lagom/BuildFuzzers.sh                     | 1 -
 Meta/Lagom/CMakeLists.txt                      | 4 ++++
 5 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c60f39ec97e..ca14984c69a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -15,6 +15,10 @@ if (CMAKE_TOOLCHAIN_FILE MATCHES "vcpkg.cmake$")
     set(CMAKE_PROJECT_ladybird_INCLUDE_BEFORE "Meta/CMake/vcpkg/generate_vcpkg_toolchain_variables.cmake")
 endif()
 
+if (APPLE AND NOT CMAKE_OSX_SYSROOT)
+    set(CMAKE_OSX_SYSROOT macosx)
+endif()
+
 project(ladybird
         VERSION 0.1.0
         LANGUAGES C CXX
diff --git a/Meta/CMake/vcpkg/base-triplets/arm64-osx.cmake b/Meta/CMake/vcpkg/base-triplets/arm64-osx.cmake
index 312c49acc42..8fac22a5532 100644
--- a/Meta/CMake/vcpkg/base-triplets/arm64-osx.cmake
+++ b/Meta/CMake/vcpkg/base-triplets/arm64-osx.cmake
@@ -2,5 +2,6 @@ set(VCPKG_CMAKE_SYSTEM_NAME Darwin)
 set(VCPKG_TARGET_ARCHITECTURE arm64)
 set(VCPKG_OSX_ARCHITECTURES arm64)
 set(VCPKG_CRT_LINKAGE dynamic)
+set(VCPKG_OSX_SYSROOT macosx)
 
 include(${CMAKE_CURRENT_LIST_DIR}/base.cmake)
diff --git a/Meta/CMake/vcpkg/base-triplets/x64-osx.cmake b/Meta/CMake/vcpkg/base-triplets/x64-osx.cmake
index ce125bc4ede..6ea0c2f1dfc 100644
--- a/Meta/CMake/vcpkg/base-triplets/x64-osx.cmake
+++ b/Meta/CMake/vcpkg/base-triplets/x64-osx.cmake
@@ -2,5 +2,6 @@ set(VCPKG_CMAKE_SYSTEM_NAME Darwin)
 set(VCPKG_TARGET_ARCHITECTURE x64)
 set(VCPKG_OSX_ARCHITECTURES x86_64)
 set(VCPKG_CRT_LINKAGE dynamic)
+set(VCPKG_OSX_SYSROOT macosx)
 
 include(${CMAKE_CURRENT_LIST_DIR}/base.cmake)
diff --git a/Meta/Lagom/BuildFuzzers.sh b/Meta/Lagom/BuildFuzzers.sh
index b6f9aa48d77..73118108769 100755
--- a/Meta/Lagom/BuildFuzzers.sh
+++ b/Meta/Lagom/BuildFuzzers.sh
@@ -60,7 +60,6 @@ cmake -GNinja --preset=Distribution -B Build/tools \
     -DCMAKE_INSTALL_PREFIX=Build/tool-install \
     -DCMAKE_C_COMPILER=$BEST_CLANG_CANDIDATE \
     -DCMAKE_CXX_COMPILER="${BEST_CLANG_CANDIDATE/clang/clang++}" \
-    -DCMAKE_OSX_SYSROOT=macosx \
     -Dpackage=LagomTools
 ninja -C Build/tools install
 
diff --git a/Meta/Lagom/CMakeLists.txt b/Meta/Lagom/CMakeLists.txt
index d343477b3ab..4c06f850f6d 100644
--- a/Meta/Lagom/CMakeLists.txt
+++ b/Meta/Lagom/CMakeLists.txt
@@ -1,5 +1,9 @@
 cmake_minimum_required (VERSION 3.21)
 
+if (APPLE AND NOT CMAKE_OSX_SYSROOT)
+    set(CMAKE_OSX_SYSROOT macosx)
+endif()
+
 project(
     Lagom
     VERSION 0.0.0