qt6-base-fourier: GL_ALPHA → GL_R8 on OpenGL ES 3.x

Three small runtime checks in qtbase 6.11.0:

1. src/opengl/qopengltextureglyphcache.cpp createTextureData() and
   load_glyph_image_to_texture() — the `#else` branch (active when
   qtbase is built with QT_CONFIG(opengles2), every aarch64 distro)
   hard-codes GL_ALPHA without checking the runtime context's ES
   version. Replace with `useR8 = ctx->format().majorVersion() >= 3`
   so ES 3+ contexts get GL_R8 + GL_RED.

2. src/gui/rhi/qrhigles2.cpp toGlTextureFormat() RED_OR_ALPHA8 case
   — gated only on caps.coreProfile. Extend with
   `caps.gles && caps.ctxMajor >= 3`.

3. src/opengl/qopengltextureuploader.cpp Format_Alpha8 and
   Format_Grayscale8 cases — short-circuit on `context->isOpenGLES()`
   before reaching the swizzle fallback. Restrict to ES 2 only so
   ES 3+ falls through to the existing TextureSwizzle path.

Discovered while validating chromium-fourier patch 3/3 (NV12
EXTERNAL_OES) on ohm. The chrome stall, VLC vout init failure and
mpv "could not initialize video chain" all share this Qt 6 root
cause: every Qt application running on Mali / panfrost / panthor
under a KWin Wayland session emits glTexImage2D(GL_ALPHA) on every
text-glyph cache upload, mesa returns GL_INVALID_VALUE, the
compositor's frame-callback path stalls, and every wayland video
client deadlocks behind it.

PKGBUILD inherits from extra/qt6-base 6.11.0-2 with arch+=aarch64,
epoch=1 to dominate Arch's pkgrel until upstream lands the fix.
qt6-base-cflags.patch and qt6-base-nostrip.patch carried verbatim
from upstream packaging.

KWIN_PIVOT.md (in chromium-fourier/) carries the full diagnosis
thread.

arch/qt6-base-fourier/PKGBUILD

@@ -0,0 +1,192 @@
+# Maintainer: Markus Fritsche <mfritsche@reauktion.de>
+# Upstream maintainer: Antonio Rojas <arojas@archlinux.org>
+# Upstream contributor: Andrea Scarpino <andrea@archlinux.org>
+#
+# qt6-base-fourier — Qt 6 base with the GL_TEXTURE_*_OPENGL_ES_3 fix
+# unlocked. Adds three small runtime checks so that
+# QOpenGLTextureGlyphCache, QRhiGles2 (RED_OR_ALPHA8 path) and
+# QOpenGLTextureUploader (Format_Alpha8 / Format_Grayscale8) pick
+# GL_R8 instead of GL_ALPHA when the live OpenGL context advertises
+# ES 3.x or newer. Without those patches Qt 6 emits
+# `glTexImage2D(internalFormat=GL_ALPHA)` on Mali-class GLES3
+# hardware (mesa panfrost / panthor) — every call returns
+# GL_INVALID_VALUE, every dependent glTexSubImage2D errors at level
+# 0, and KWin's compositor frame-callback path stalls so badly that
+# every Wayland video client deadlocks. Discovered while validating
+# chromium-fourier patch 3/3 (NV12 zero-copy) on ohm (PineTab2 /
+# RK3566 / hantro mainline) and the chrome+VLC+mpv stalls turned out
+# to share a Qt root cause. See ../chromium-fourier/KWIN_PIVOT.md
+# for the diagnosis story and the upstream-targetable patch set.
+
+# pkgbase stays as qt6-base so $_pkgfn (= ${pkgbase/6-/} = "qtbase")
+# resolves correctly. The "-fourier" suffix lives only in the
+# directory name and the commit history; epoch=1 gives our local
+# build strict precedence over upstream pkgrel=2 until upstream lands
+# the GL_R8/ES3 fix and we can drop the epoch.
+pkgbase=qt6-base
+pkgname=(qt6-base
+         qt6-xcb-private-headers)
+_pkgver=6.11.0
+pkgver=${_pkgver/-/}
+pkgrel=2
+epoch=1
+arch=(aarch64 x86_64)
+url='https://www.qt.io'
+license=(GPL-3.0-only
+         LGPL-3.0-only
+         LicenseRef-Qt-Commercial
+         Qt-GPL-exception-1.0)
+pkgdesc='A cross-platform application and UI framework'
+depends=(brotli
+         dbus
+         double-conversion
+         fontconfig
+         freetype2
+         gcc-libs
+         glib2
+         glibc
+         harfbuzz
+         icu
+         krb5
+         libb2
+         libcups
+         libdrm
+         libgl
+         libice
+         libinput
+         libjpeg-turbo
+         libpng
+         libproxy
+         libsm
+         liburing
+         libx11
+         libxcb
+         libxkbcommon
+         libxkbcommon-x11
+         md4c
+         mesa
+         mtdev
+         openssl
+         pcre2
+         shared-mime-info
+         sqlite
+         systemd-libs
+         tslib
+         wayland
+         xcb-util-cursor
+         xcb-util-image
+         xcb-util-keysyms
+         xcb-util-renderutil
+         xcb-util-wm
+         xdg-utils
+         zlib
+         zstd)
+makedepends=(alsa-lib
+             cmake
+             cups
+             freetds
+             git
+             gst-plugins-base-libs
+             gtk3
+             jemalloc
+             libfbclient
+             libpulse
+             mariadb-libs
+             ninja
+             postgresql
+             renderdoc
+             unixodbc
+             vulkan-headers
+             xmlstarlet)
+optdepends=('freetds: MS SQL driver'
+            'gdk-pixbuf2: GTK platform plugin'
+            'gtk3: GTK platform plugin'
+            'libfbclient: Firebird/iBase driver'
+            'mariadb-libs: MariaDB driver'
+            'pango: GTK platform plugin'
+            'perl: for syncqt'
+            'postgresql-libs: PostgreSQL driver'
+            'unixodbc: ODBC driver')
+groups=(qt6)
+_pkgfn=${pkgbase/6-/}
+source=(git+https://code.qt.io/qt/$_pkgfn#tag=v$_pkgver
+        patches/qt6-base-cflags.patch
+        patches/qt6-base-nostrip.patch
+        patches/0001-qopengltextureglyphcache-pick-GL_R8-on-ES3.patch
+        patches/0002-qrhigles2-RED_OR_ALPHA8-pick-GL_R8-on-ES3.patch
+        patches/0003-qopengltextureuploader-pick-GL_R8-on-ES3.patch)
+sha256sums=('2223c075e95d86f8dbf6395b025a74d996c418f094453c903290e3c2663fbed2'
+            '5411edbe215c24b30448fac69bd0ba7c882f545e8cf05027b2b6e2227abc5e78'
+            '4b93f6a79039e676a56f9d6990a324a64a36f143916065973ded89adc621e094'
+            'SKIP'
+            'SKIP'
+            'SKIP')
+
+prepare() {
+  patch -d $_pkgfn -p1 < patches/qt6-base-cflags.patch # Use system CFLAGS
+  patch -d $_pkgfn -p1 < patches/qt6-base-nostrip.patch # Don't strip binaries with qmake
+
+  # cherry-pick needs git author identity; git-cli refuses without it.
+  git -C $_pkgfn -c user.email=fourier@build -c user.name='qt6-base-fourier build' \
+      cherry-pick -n 8b54513cdcf62047376a5d27d784ad68a8f235bf # Fix qdbus crashes
+
+  # qt6-base-fourier — three small runtime-checks that pick GL_R8 over
+  # GL_ALPHA when the live GL context is ES 3 or newer. See patches/
+  # for the per-site diagnosis. The chromium-fourier KWIN_PIVOT.md
+  # writeup carries the discovery thread.
+  patch -d $_pkgfn -p1 < patches/0001-qopengltextureglyphcache-pick-GL_R8-on-ES3.patch
+  patch -d $_pkgfn -p1 < patches/0002-qrhigles2-RED_OR_ALPHA8-pick-GL_R8-on-ES3.patch
+  patch -d $_pkgfn -p1 < patches/0003-qopengltextureuploader-pick-GL_R8-on-ES3.patch
+}
+
+build() {
+  # Set no_direct_extern_access based on architecture
+  if [[ $CARCH == "aarch64" || $CARCH == "riscv64" ]]; then
+    _no_direct_extern_access=OFF
+  else
+    _no_direct_extern_access=ON
+  fi
+
+  cmake -B build -S $_pkgfn -G Ninja \
+    -DCMAKE_INSTALL_PREFIX=/usr \
+    -DCMAKE_BUILD_TYPE=RelWithDebInfo \
+    -DINSTALL_BINDIR=lib/qt6/bin \
+    -DINSTALL_PUBLICBINDIR=bin \
+    -DINSTALL_LIBEXECDIR=lib/qt6 \
+    -DINSTALL_DOCDIR=share/doc/qt6 \
+    -DINSTALL_ARCHDATADIR=lib/qt6 \
+    -DINSTALL_DATADIR=share/qt6 \
+    -DINSTALL_INCLUDEDIR=include/qt6 \
+    -DINSTALL_MKSPECSDIR=lib/qt6/mkspecs \
+    -DINSTALL_EXAMPLESDIR=share/doc/qt6/examples \
+    -DFEATURE_journald=ON \
+    -DFEATURE_libproxy=ON \
+    -DFEATURE_openssl_linked=ON \
+    -DFEATURE_system_sqlite=ON \
+    -DFEATURE_system_xcb_xinput=ON \
+    -DFEATURE_no_direct_extern_access=$_no_direct_extern_access \
+    -DCMAKE_INTERPROCEDURAL_OPTIMIZATION=ON \
+    -DCMAKE_MESSAGE_LOG_LEVEL=STATUS
+  cmake --build build
+}
+
+package_qt6-base() {
+  pkgdesc='A cross-platform application and UI framework'
+  depends+=(qt6-translations)
+  DESTDIR="$pkgdir" cmake --install build
+
+  install -Dm644 $_pkgfn/LICENSES/* -t "$pkgdir"/usr/share/licenses/$pkgbase
+}
+
+package_qt6-xcb-private-headers() {
+  pkgdesc='Private headers for Qt6 Xcb'
+
+  depends=("qt6-base=$pkgver")
+  optdepends=()
+  groups=()
+
+  cd $_pkgfn
+  install -d -m755 "$pkgdir"/usr/include/qt6xcb-private/gl_integrations
+  cp -r src/plugins/platforms/xcb/*.h "$pkgdir"/usr/include/qt6xcb-private/
+  cp -r src/plugins/platforms/xcb/gl_integrations/*.h "$pkgdir"/usr/include/qt6xcb-private/gl_integrations/
+}