When I run ./mach static-analysis check-syntax dom/ipc/ContentChild.cpp, I get

 0:02.19 /home/simon/.mozbuild/clang/bin/clang++ -std=gnu++17 -o /dev/null -c -I/home/simon/work/fuzzy/obj-x86_64-pc-linux-gnu/dist/stl_wrappers -I/home/simon/work/fuzzy/obj-x86_64-pc-linux-gnu/dist/system_wrappers -include /home/simon/work/fuzzy/config/gcc_hidden.h -DDEBUG=1 -DOS_POSIX=1 -DOS_LINUX=1 '-DBIN_SUFFIX=""' '-DMOZ_APP_NAME="firefox"' -DMOZ_HAS_MOZGLUE -DMOZILLA_INTERNAL_API -DIMPL_LIBXUL -DSTATIC_EXPORTABLE_JS_API -I/home/simon/work/fuzzy/dom/ipc -I/home/simon/work/fuzzy/obj-x86_64-pc-linux-gnu/dom/ipc -I/home/simon/work/fuzzy/obj-x86_64-pc-linux-gnu/ipc/ipdl/_ipdlheaders -I/home/simon/work/fuzzy/ipc/chromium/src -I/home/simon/work/fuzzy/ipc/glue -I/home/simon/work/fuzzy/caps -I/home/simon/work/fuzzy/chrome -I/home/simon/work/fuzzy/docshell/base -I/home/simon/work/fuzzy/dom/base -I/home/simon/work/fuzzy/dom/bindings -I/home/simon/work/fuzzy/dom/events -I/home/simon/work/fuzzy/dom/filesystem -I/home/simon/work/fuzzy/dom/geolocation -I/home/simon/work/fuzzy/dom/media/webspeech/synth/ipc -I/home/simon/work/fuzzy/dom/security -I/home/simon/work/fuzzy/dom/storage -I/home/simon/work/fuzzy/extensions/spellcheck/src -I/home/simon/work/fuzzy/gfx/2d -I/home/simon/work/fuzzy/hal/sandbox -I/home/simon/work/fuzzy/js/xpconnect/loader -I/home/simon/work/fuzzy/js/xpconnect/src -I/home/simon/work/fuzzy/layout/base -I/home/simon/work/fuzzy/media/webrtc -I/home/simon/work/fuzzy/netwerk/base -I/home/simon/work/fuzzy/netwerk/protocol/http -I/home/simon/work/fuzzy/toolkit/components/printingui/ipc -I/home/simon/work/fuzzy/toolkit/crashreporter -I/home/simon/work/fuzzy/toolkit/xre -I/home/simon/work/fuzzy/uriloader/exthandler -I/home/simon/work/fuzzy/widget -I/home/simon/work/fuzzy/xpcom/base -I/home/simon/work/fuzzy/xpcom/threads -I/home/simon/work/fuzzy/modules/libjar -I/home/simon/work/fuzzy/obj-x86_64-pc-linux-gnu/dist/include -I/home/simon/work/fuzzy/obj-x86_64-pc-linux-gnu/dist/include/nspr -I/home/simon/work/fuzzy/obj-x86_64-pc-linux-gnu/dist/include/nss -fPIC -DMOZILLA_CLIENT -include /home/simon/work/fuzzy/obj-x86_64-pc-linux-gnu/mozilla-config.h -Qunused-arguments -Qunused-arguments -Wall -Wbitfield-enum-conversion -Wempty-body -Wignored-qualifiers -Woverloaded-virtual -Wpointer-arith -Wshadow-field-in-constructor-modified -Wsign-compare -Wtype-limits -Wunreachable-code -Wunreachable-code-return -Wwrite-strings -Wno-invalid-offsetof -Wclass-varargs -Wempty-init-stmt -Wfloat-overflow-conversion -Wfloat-zero-conversion -Wloop-analysis -Wc++2a-compat -Wcomma -Wimplicit-fallthrough -Wunused-function -Wunused-variable -Werror=non-literal-null-conversion -Wstring-conversion -Wtautological-overlap-compare -Wtautological-unsigned-enum-zero-compare -Wtautological-unsigned-zero-compare -Wno-error=tautological-type-limit-compare -Wno-inline-new-delete -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=backend-plugin -Wno-error=return-std-move -Wno-error=atomic-alignment -Wformat -Wformat-security -Wno-gnu-zero-variadic-macro-arguments -Wno-unknown-warning-option -fno-sized-deallocation -fno-aligned-new -fno-exceptions -fno-strict-aliasing -fno-rtti -fno-exceptions -fno-math-errno -pthread -pipe -g -Xclang -load -Xclang /home/simon/work/fuzzy/obj-x86_64-pc-linux-gnu/build/clang-plugin/libclang-plugin.so -Xclang -add-plugin -Xclang moz-check -Og -fno-omit-frame-pointer -funwind-tables -Werror -I/home/simon/work/fuzzy/widget/gtk/compat-gtk3 -I/usr/include/gtk-3.0 -I/usr/include/pango-1.0 -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/fribidi -I/usr/include/harfbuzz -I/usr/include/freetype2 -I/usr/include/libpng16 -I/usr/include/cairo -I/usr/include/pixman-1 -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/libmount -I/usr/include/blkid -I/usr/include/uuid -I/usr/include/gio-unix-2.0 -I/usr/include/libdrm -I/usr/include/atk-1.0 -I/usr/include/at-spi2-atk/2.0 -I/usr/include/at-spi-2.0 -I/usr/include/dbus-1.0 -I/usr/lib64/dbus-1.0/include -I/usr/include/gtk-3.0/unix-print -pthread -Wno-error=shadow -fexperimental-new-pass-manager -ferror-limit=0 /home/simon/work/fuzzy/dom/ipc/ContentChild.cpp -fsyntax-only
clang-9: error: no such file or directory: ''-DBIN_SUFFIX=""''
clang-9: error: no such file or directory: ''-DMOZ_APP_NAME="firefox"''

Apparently, the two defines are falsely escaped with '