From 9b356320bb2ba913333fe99c70da733edabbd239 Mon Sep 17 00:00:00 2001
From: Louis Opter <louis@opter.org>
Date: Sat, 2 May 2026 23:15:30 +0000
Subject: [PATCH] qt6.qtwebengine: fix build on Darwin

Assisted-by: Claude Code (Claude Opus 4.7, Claude Opus 5)
---
 .../clang-base-path-from-cmake-compiler.patch | 225 ++++++++++++++++++
 .../qt-6/modules/qtwebengine/default.nix      |   8 +-
 .../lflags-remove-strip-darwin-isysroot.patch |  76 ++++++
 3 files changed, 307 insertions(+), 2 deletions(-)
 create mode 100644 pkgs/development/libraries/qt-6/modules/qtwebengine/clang-base-path-from-cmake-compiler.patch
 create mode 100644 pkgs/development/libraries/qt-6/modules/qtwebengine/lflags-remove-strip-darwin-isysroot.patch

diff --git a/pkgs/development/libraries/qt-6/modules/qtwebengine/clang-base-path-from-cmake-compiler.patch b/pkgs/development/libraries/qt-6/modules/qtwebengine/clang-base-path-from-cmake-compiler.patch
new file mode 100644
index 000000000000..fe0d638fddff
--- /dev/null
+++ b/pkgs/development/libraries/qt-6/modules/qtwebengine/clang-base-path-from-cmake-compiler.patch
@@ -0,0 +1,225 @@
+From 3f9ac6721aaeb9e9dd6347164219dc99bfde2a29 Mon Sep 17 00:00:00 2001
+From: Louis Opter <louis@opter.org>
+Date: Sat, 2 May 2026 22:22:03 +0000
+Subject: [PATCH 1/2] CMake: rename QWELibClang_{BIN,BASE}_PATH to
+ QWELibClang_LLVM_{BIN,BASE}_PATH
+
+These cache vars hold the LLVM installation prefix's bin dir and root
+directory -- where llvm-config and libclang.{so,dylib,dll} live -- but
+the unqualified names suggest "the path to the clang binary." Renaming
+makes the LLVM-prefix purpose explicit and frees the unqualified
+namespace for a separate compiler-invocation-prefix distinction
+introduced in a follow-up commit.
+
+No functional change.
+---
+ cmake/FindQWELibClang.cmake    | 24 ++++++++++++------------
+ cmake/QtToolchainHelpers.cmake |  4 ++--
+ 2 files changed, 14 insertions(+), 14 deletions(-)
+
+diff --git a/cmake/FindQWELibClang.cmake b/cmake/FindQWELibClang.cmake
+index 3f6f484..ef7d570 100644
+--- a/cmake/FindQWELibClang.cmake
++++ b/cmake/FindQWELibClang.cmake
+@@ -10,7 +10,7 @@ else()
+ endif()
+ 
+ function(try_clang_executable Clang_EXECUTABLE)
+-    if(NOT DEFINED QWELibClang_BIN_PATH)
++    if(NOT DEFINED QWELibClang_LLVM_BIN_PATH)
+         # Extract the base dir from the clang executable
+         if(MSVC)
+             set(CLANG_PRINT_PATH_COMMAND /clang:-print-prog-name=clang)
+@@ -28,13 +28,13 @@ function(try_clang_executable Clang_EXECUTABLE)
+         file(TO_CMAKE_PATH "${clang_output}" clang_output) # $base_path/bin/clang
+         get_filename_component(clang_output "${clang_output}" DIRECTORY) # $base_path/bin
+ 
+-        set(QWELibClang_BIN_PATH "${clang_output}" CACHE INTERNAL "internal")
++        set(QWELibClang_LLVM_BIN_PATH "${clang_output}" CACHE INTERNAL "internal")
+     endif()
+ 
+     # Try to find the llvm-config executable, and extract the library location from it
+     find_program(QWELibClang_LLVM_CONFIG_EXECUTABLE
+         NAMES llvm-config
+-        PATHS ${QWELibClang_BIN_PATH}
++        PATHS ${QWELibClang_LLVM_BIN_PATH}
+         NO_DEFAULT_PATH)
+ 
+     if (QWELibClang_LLVM_CONFIG_EXECUTABLE)
+@@ -45,17 +45,17 @@ function(try_clang_executable Clang_EXECUTABLE)
+             OUTPUT_STRIP_TRAILING_WHITESPACE
+         )
+         file(TO_CMAKE_PATH "${llvm_config_output}" llvm_config_output)
+-        get_filename_component(QWELibClang_BAS_PATH "${llvm_config_output}" DIRECTORY)
++        get_filename_component(QWELibClang_LLVM_BAS_PATH "${llvm_config_output}" DIRECTORY)
+     else()
+         # No llvm-config. Get the base path from the binary directory
+         # This is the expected path for Windows and macOS
+-        get_filename_component(QWELibClang_BAS_PATH "${QWELibClang_BIN_PATH}" DIRECTORY)
++        get_filename_component(QWELibClang_LLVM_BAS_PATH "${QWELibClang_LLVM_BIN_PATH}" DIRECTORY)
+     endif()
+-    set(QWELibClang_BASE_PATH ${QWELibClang_BAS_PATH} CACHE INTERNAL "internal")
++    set(QWELibClang_LLVM_BASE_PATH ${QWELibClang_LLVM_BAS_PATH} CACHE INTERNAL "internal")
+ 
+     find_file(Libclang_LIBRARY
+         NAMES libclang.dll libclang.dylib libclang.so
+-        PATHS ${llvm_config_output} ${QWELibClang_BIN_PATH} ${QWELibClang_BASE_PATH}/lib ${QWELibClang_BASE_PATH}/lib64
++        PATHS ${llvm_config_output} ${QWELibClang_LLVM_BIN_PATH} ${QWELibClang_LLVM_BASE_PATH}/lib ${QWELibClang_LLVM_BASE_PATH}/lib64
+         NO_DEFAULT_PATH)
+ 
+     get_filename_component(Libclang_LIBRARY_DIR "${Libclang_LIBRARY}" DIRECTORY)
+@@ -110,9 +110,9 @@ if(Clang_EXECUTABLE)
+ endif()
+ 
+ # As a backup find the clang version used by pyside on CI
+-if(NOT (QWELibClang_LIBRARY_DIR AND QWELibClang_BASE_PATH AND QWELibClang_BIN_PATH) AND DEFINED ENV{LLVM_DYNAMIC_LIBS_100})
++if(NOT (QWELibClang_LIBRARY_DIR AND QWELibClang_LLVM_BASE_PATH AND QWELibClang_LLVM_BIN_PATH) AND DEFINED ENV{LLVM_DYNAMIC_LIBS_100})
+     unset(Clang_EXECUTABLE)
+-    unset(QWELibClang_BIN_PATH CACHE)
++    unset(QWELibClang_LLVM_BIN_PATH CACHE)
+     find_program(Clang_EXECUTABLE NAMES clang PATHS $ENV{LLVM_DYNAMIC_LIBS_100}/bin)
+     if(Clang_EXECUTABLE)
+         try_clang_executable(${Clang_EXECUTABLE})
+@@ -122,12 +122,12 @@ endif()
+ include(FindPackageHandleStandardArgs)
+ 
+ find_package_handle_standard_args(QWELibClang
+-    REQUIRED_VARS QWELibClang_LIBRARY_DIR QWELibClang_BASE_PATH QWELibClang_BIN_PATH
++    REQUIRED_VARS QWELibClang_LIBRARY_DIR QWELibClang_LLVM_BASE_PATH QWELibClang_LLVM_BIN_PATH
+     VERSION_VAR QWELibClang_VERSION
+ )
+ 
+-mark_as_advanced(QWELibClang_BIN_PATH)
+-mark_as_advanced(QWELibClang_BASE_PATH)
++mark_as_advanced(QWELibClang_LLVM_BIN_PATH)
++mark_as_advanced(QWELibClang_LLVM_BASE_PATH)
+ mark_as_advanced(QWELibClang_LIBRARY_DIR)
+ mark_as_advanced(QWELibClang_RUNTIME_PATH)
+ mark_as_advanced(QWELibClang_RESOURCE_PATH)
+diff --git a/cmake/QtToolchainHelpers.cmake b/cmake/QtToolchainHelpers.cmake
+index b0cd2dd..885fd53 100644
+--- a/cmake/QtToolchainHelpers.cmake
++++ b/cmake/QtToolchainHelpers.cmake
+@@ -404,7 +404,7 @@ macro(append_compiler_linker_sdk_setup)
+             )
+         endif()
+         list(APPEND gnArgArg
+-            clang_base_path="${QWELibClang_BASE_PATH}"
++            clang_base_path="${QWELibClang_LLVM_BASE_PATH}"
+             clang_version="${clang_runtime_path_version}"
+             clang_use_chrome_plugins=false
+             fatal_linker_warnings=false
+@@ -455,7 +455,7 @@ macro(append_compiler_linker_sdk_setup)
+         endif()
+     else()
+         if(QT_FEATURE_use_lld_linker OR QT_FEATURE_webengine_rust_build)
+-            list(APPEND gnArgArg clang_base_path="${QWELibClang_BASE_PATH}")
++            list(APPEND gnArgArg clang_base_path="${QWELibClang_LLVM_BASE_PATH}")
+             if (QT_FEATURE_webengine_rust_build)
+                 get_clang_runtime_path_version(clang_runtime_path_version)
+                 list(APPEND gnArgArg clang_version="${clang_runtime_path_version}")
+
+From 76d33954567d9d96a738a4f1e8baea69d66286b2 Mon Sep 17 00:00:00 2001
+From: Louis Opter <louis@opter.org>
+Date: Sat, 2 May 2026 22:22:55 +0000
+Subject: [PATCH 2/2] CMake: source clang_base_path from CMake-detected
+ compiler dir
+
+The clang_base_path argument fed to Chromium's build system is used to
+invoke ${clang_base_path}/bin/clang++ when compiling chromium sources.
+Since 695dd68f8 ("Optionally build using rust"), it has been derived
+from QWELibClang_LLVM_BIN_PATH, which in turn is computed by running
+"clang -print-prog-name=clang" and taking dirname twice. That
+indirection produces wrong results on wrapped toolchains (ccache,
+distcc, sccache, nixpkgs cc-wrapper) where the wrapper script and the
+underlying clang live in different directories: the wrapper forwards
+the flag, the bare clang reports its own absolute path, and
+clang_base_path ends up at the bare LLVM prefix. The downstream
+chromium compilation then invokes the unwrapped clang, bypassing
+wrapper-injected flags such as -isystem for the libc++ headers, and
+fails on "'atomic' file not found".
+
+The print-prog-name indirection has a legitimate other purpose in this
+file: locating llvm-config and libclang.{so,dylib,dll}. These live in
+the bare LLVM prefix, not the wrapper directory, because wrappers are
+deliberately scoped to compile-driver flag injection: they ship the
+cc/c++/cpp shims plus bintools symlinks, nothing else -- no lib/ and
+no LLVM dev tools alongside. So we cannot simply revert the
+indirection; QWELibClang_LLVM_BIN_PATH and QWELibClang_LLVM_BASE_PATH
+remain unchanged for the libclang/llvm-config lookups they feed.
+
+Instead, introduce QWELibClang_COMPILER_BIN_PATH and
+QWELibClang_COMPILER_BASE_PATH, derived directly from Clang_EXECUTABLE
+via dirname, and route clang_base_path in QtToolchainHelpers.cmake
+through them. On a non-wrapped toolchain the two paths are identical,
+so this change is a no-op there.
+
+Reproduced on x86_64-darwin with nixpkgs (Qt 6.10.2 worked because the
+pre-695dd68f8 inline "dirname dirname ${CMAKE_OBJCXX_COMPILER}" ended
+up at the wrapper directory; Qt 6.11.0 fails). After this change,
+chromium compilation invokes the wrapper, NIX_CFLAGS_COMPILE flows
+through, and qtwebengine builds successfully.
+---
+ cmake/FindQWELibClang.cmake    | 12 ++++++++++++
+ cmake/QtToolchainHelpers.cmake |  4 ++--
+ 2 files changed, 14 insertions(+), 2 deletions(-)
+
+diff --git a/cmake/FindQWELibClang.cmake b/cmake/FindQWELibClang.cmake
+index ef7d570..62c87be 100644
+--- a/cmake/FindQWELibClang.cmake
++++ b/cmake/FindQWELibClang.cmake
+@@ -31,6 +31,15 @@ function(try_clang_executable Clang_EXECUTABLE)
+         set(QWELibClang_LLVM_BIN_PATH "${clang_output}" CACHE INTERNAL "internal")
+     endif()
+ 
++    if(NOT DEFINED QWELibClang_COMPILER_BIN_PATH)
++        # Directory of the compiler that CMake invokes; on a wrapped toolchain
++        # this differs from QWELibClang_LLVM_BIN_PATH.
++        get_filename_component(compiler_bin_path "${Clang_EXECUTABLE}" DIRECTORY) # $compiler_base_path/bin
++        get_filename_component(compiler_base_path "${compiler_bin_path}" DIRECTORY) # $compiler_base_path
++        set(QWELibClang_COMPILER_BIN_PATH "${compiler_bin_path}" CACHE INTERNAL "internal")
++        set(QWELibClang_COMPILER_BASE_PATH "${compiler_base_path}" CACHE INTERNAL "internal")
++    endif()
++
+     # Try to find the llvm-config executable, and extract the library location from it
+     find_program(QWELibClang_LLVM_CONFIG_EXECUTABLE
+         NAMES llvm-config
+@@ -113,6 +122,7 @@ endif()
+ if(NOT (QWELibClang_LIBRARY_DIR AND QWELibClang_LLVM_BASE_PATH AND QWELibClang_LLVM_BIN_PATH) AND DEFINED ENV{LLVM_DYNAMIC_LIBS_100})
+     unset(Clang_EXECUTABLE)
+     unset(QWELibClang_LLVM_BIN_PATH CACHE)
++    unset(QWELibClang_COMPILER_BIN_PATH CACHE)
+     find_program(Clang_EXECUTABLE NAMES clang PATHS $ENV{LLVM_DYNAMIC_LIBS_100}/bin)
+     if(Clang_EXECUTABLE)
+         try_clang_executable(${Clang_EXECUTABLE})
+@@ -128,6 +138,8 @@ find_package_handle_standard_args(QWELibClang
+ 
+ mark_as_advanced(QWELibClang_LLVM_BIN_PATH)
+ mark_as_advanced(QWELibClang_LLVM_BASE_PATH)
++mark_as_advanced(QWELibClang_COMPILER_BIN_PATH)
++mark_as_advanced(QWELibClang_COMPILER_BASE_PATH)
+ mark_as_advanced(QWELibClang_LIBRARY_DIR)
+ mark_as_advanced(QWELibClang_RUNTIME_PATH)
+ mark_as_advanced(QWELibClang_RESOURCE_PATH)
+diff --git a/cmake/QtToolchainHelpers.cmake b/cmake/QtToolchainHelpers.cmake
+index 885fd53..3c86a03 100644
+--- a/cmake/QtToolchainHelpers.cmake
++++ b/cmake/QtToolchainHelpers.cmake
+@@ -404,7 +404,7 @@ macro(append_compiler_linker_sdk_setup)
+             )
+         endif()
+         list(APPEND gnArgArg
+-            clang_base_path="${QWELibClang_LLVM_BASE_PATH}"
++            clang_base_path="${QWELibClang_COMPILER_BASE_PATH}"
+             clang_version="${clang_runtime_path_version}"
+             clang_use_chrome_plugins=false
+             fatal_linker_warnings=false
+@@ -455,7 +455,7 @@ macro(append_compiler_linker_sdk_setup)
+         endif()
+     else()
+         if(QT_FEATURE_use_lld_linker OR QT_FEATURE_webengine_rust_build)
+-            list(APPEND gnArgArg clang_base_path="${QWELibClang_LLVM_BASE_PATH}")
++            list(APPEND gnArgArg clang_base_path="${QWELibClang_COMPILER_BASE_PATH}")
+             if (QT_FEATURE_webengine_rust_build)
+                 get_clang_runtime_path_version(clang_runtime_path_version)
+                 list(APPEND gnArgArg clang_version="${clang_runtime_path_version}")
diff --git a/pkgs/development/libraries/qt-6/modules/qtwebengine/default.nix b/pkgs/development/libraries/qt-6/modules/qtwebengine/default.nix
index b0ec0c094a43..084c7a411b0e 100644
--- a/pkgs/development/libraries/qt-6/modules/qtwebengine/default.nix
+++ b/pkgs/development/libraries/qt-6/modules/qtwebengine/default.nix
@@ -117,6 +117,12 @@ qtModule {
 
     # Reproducibility QTBUG-136068
     ./gn-object-sorted.patch
+  ]
+  # Remove once merged with upstream
+  ++ lib.optionals stdenv.hostPlatform.isDarwin [
+    ./clang-base-path-from-cmake-compiler.patch
+
+    ./lflags-remove-strip-darwin-isysroot.patch
   ];
 
   postPatch = ''
@@ -158,8 +164,6 @@ qtModule {
   + lib.optionalString stdenv.hostPlatform.isDarwin ''
     substituteInPlace cmake/QtToolchainHelpers.cmake \
       --replace-fail "/usr/bin/xcrun" "${xcbuild}/bin/xcrun"
-    substituteInPlace cmake/QtToolchainHelpers.cmake \
-      --replace-fail 'clang_base_path="''${QWELibClang_BASE_PATH}"' 'clang_base_path="${stdenv.cc}"'
 
     # xcbuild's xcrun doesn't implement the real (proprietary) Metal shader
     # compiler, so this check always fails. The one build step that actually
diff --git a/pkgs/development/libraries/qt-6/modules/qtwebengine/lflags-remove-strip-darwin-isysroot.patch b/pkgs/development/libraries/qt-6/modules/qtwebengine/lflags-remove-strip-darwin-isysroot.patch
new file mode 100644
index 000000000000..0fd6b75e6109
--- /dev/null
+++ b/pkgs/development/libraries/qt-6/modules/qtwebengine/lflags-remove-strip-darwin-isysroot.patch
@@ -0,0 +1,76 @@
+Subject: Build: strip relative -isysroot from chromium-emitted lflags
+
+In src/{core,pdf}/configure/BUILD.root.gn.in, lflags_remove is fed to
+the rsp writer in our gn fork
+(src/3rdparty/gn/src/gn/rsp_target_writer.cc, LFLAGS case) where it
+runs std::regex_replace over the accumulated ldflags before writing
+the rsp file. The intent, per the inline comment, is to drop sysroot
+flags whose path was emitted as relative.
+
+Such relative paths are produced by chromium's mac/linux toolchain
+configs via rebase_path(sysroot, root_build_dir). For qtwebengine, the
+chromium root_build_dir is build/src/core/Release/$arch, so the
+rebased path is correct when read from there -- but the rsp file is
+consumed by the *cmake*-driven ninja link, which runs from build/. The
+two cwds differ by four levels, so the rebased path resolves to a
+non-existent location, triggering -Wmissing-sysroot and a subsequent
+"framework not found CoreFoundation" failure (linker falls back to a
+bogus sysroot, can't find /System/Library/Frameworks under it).
+
+The existing pattern only matched the Linux --sysroot=PATH single-
+token form, so the Apple two-token form '-isysroot PATH' slipped
+through untouched. Extend the alternation to cover both, and tighten
+the path match to \.\./\S+ (the prior \.\./.*\S*? was effectively
+\.\./.* and worked only because --sysroot= was the last token in
+the Linux ldflags string -- on macOS -isysroot is followed by more
+flags like -mmacos-version-min, so we need a match that stops at the
+next whitespace).
+
+Also add lflags_remove to the convert_dict target, which declares
+rsp_types but had no filter; on macOS it hits the same relative
+-isysroot issue as QtWebEngineCore (the linker fails on -lbsm because
+the bogus sysroot wins last and ld can't resolve system libs under
+it). QtWebEngineCore and QtPdf had the filter; convert_dict appears
+to have been overlooked.
+
+The good absolute -isysroot is already injected on the clang++ command
+line by cmake earlier, so stripping the bad one is sufficient
+(-isysroot is last-wins, and now only the good one remains).
+
+Reproduced on aarch64-darwin with nixpkgs's apple-sdk-15.5, on
+Qt 6.11.0. After this change qtwebengine builds successfully.
+
+diff --git a/src/core/configure/BUILD.root.gn.in b/src/core/configure/BUILD.root.gn.in
+index cf9a3fe..3b01162 100644
+--- a/src/core/configure/BUILD.root.gn.in
++++ b/src/core/configure/BUILD.root.gn.in
+@@ -107,7 +107,7 @@ if (ozone_platform_x11) {
+ 
+ shared_library("QtWebEngineCore") {
+   rsp_types = [ "objects", "archives", "libs", "ldir", "lflags" ]
+-  lflags_remove = "(--sysroot=)(\\.\\./.*\\S*?)" # ignore sysroot with realative path
++  lflags_remove = "(--sysroot=|-isysroot )\\.\\./\\S+" # ignore sysroot with relative path
+   configs += [
+     ":cpp20_config",
+     ":QtWebEngineCore_config",
+@@ -846,6 +846,7 @@ if (enable_extensions) {
+ if (enable_spellcheck) {
+   shared_library("convert_dict") {
+     rsp_types = [ "objects", "archives", "libs", "ldir", "lflags" ]
++    lflags_remove = "(--sysroot=|-isysroot )\\.\\./\\S+" # ignore sysroot with relative path
+     configs += [ "//build/config/compiler:wexit_time_destructors" ]
+     deps = [
+       "//chrome/tools/convert_dict:lib",
+diff --git a/src/pdf/configure/BUILD.root.gn.in b/src/pdf/configure/BUILD.root.gn.in
+index 72d4558..c63cfda 100644
+--- a/src/pdf/configure/BUILD.root.gn.in
++++ b/src/pdf/configure/BUILD.root.gn.in
+@@ -51,7 +51,7 @@ config("cpp20_config") {
+ static_library("QtPdf") {
+   complete_static_lib = true
+   rsp_types = [ "objects", "archives", "libs", "ldir", "lflags" ]
+-  lflags_remove = "(--sysroot=)(\\.\\./.*\\S*?)" # ignore sysroot with realative path
++  lflags_remove = "(--sysroot=|-isysroot )\\.\\./\\S+" # ignore sysroot with relative path
+   configs += [
+     ":cpp20_config",
+     ":QtPdf_config"