I tried reviewing a PR targeting staging and got this:

error: Cannot build '/nix/store/25szfqz836lmypkvmrwa22zsn4xqf3wq-expand-response-params.drv'.
       Reason: builder failed with exit code 1.
       Output paths:
         /nix/store/hd0k8s0c341wxg041g78jhggsic6s1ws-expand-response-params
       Last 9 log lines:
       > Running phase: unpackPhase
       > Running phase: patchPhase
       > Running phase: updateAutotoolsGnuConfigScriptsPhase
       > Running phase: configurePhase
       > no configure script, doing nothing
       > Running phase: buildPhase
       > gcc: error: unrecognized command-line option '-fstrict-flex-arrays=1'
       > /nix/store/9l34ijwa4q1wp0nnjbmnnrvgm8cgkn8v-bootstrap-stage1-stdenv-linux/setup: line 1824: pop_var_context: head of shell_variables not a function context
       > /nix/store/shkw4qm9qcw5sc5n1k5jznc83ny02r39-default-builder.sh: line 1: pop_var_context: head of shell_variables not a function context
       For full logs, run:
         nix log /nix/store/25szfqz836lmypkvmrwa22zsn4xqf3wq-expand-response-params.drv