`linux/runner/` is Flutter's stock GTK host program. On macOS the GTK
development headers are absent, so clangd cannot resolve <gtk/gtk.h>,
G_DECLARE_FINAL_TYPE never expands, and a six-line main.cc reports seven
errors for symbols that macro produces.
They are editor diagnostics, not build errors — the file compiles
unchanged on Linux, and nothing in the Flutter toolchain reads clangd.
Suppressing them beats editing generated code the Linux build needs.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>