t27c on fifo.t27 -- a pointer mutation the tests cannot see

head_ptr + 1 to + 3 in one sed: every test still passes, because the suite asserts fill counts and flags, never pointer values -- the exact hole a torn multi-bit pointer would slip through; git restores the spec.

files $ t27c test-report specs/fpga/fifo.t27 --specs-dir specs | sed -n '1,7p'                          
--- test report: specs/fpga/fifo.t27 ---                                                                

  tests       18                                                                                        
  pass        18                                                                                        
  FAIL        0                                                                                         
  invariants  6   proved -- comptime, so compiling IS the check                                         
  rate    100.0%                                                                                        
files $ sed -i '' 's/(state.head_ptr + 1) % cfg.depth/(state.head_ptr + 3) % cfg.depth/' specs/fpga/fifo
.t27 && git diff -U0 specs/fpga/fifo.t27 | tail -n 2                                                    
-        result.head_ptr = (state.head_ptr + 1) % cfg.depth;                                            
+        result.head_ptr = (state.head_ptr + 3) % cfg.depth;                                            
files $ t27c test-report specs/fpga/fifo.t27 --specs-dir specs | sed -n '1,7p'                          
--- test report: specs/fpga/fifo.t27 ---                                                                

  tests       18                                                                                        
  pass        18                                                                                        
  FAIL        0                                                                                         
  invariants  6   proved -- comptime, so compiling IS the check                                         
  rate    100.0%                                                                                        
files $ git checkout specs/fpga/fifo.t27 && sha256sum specs/fpga/fifo.t27                               
Updated 1 path from the index                                                                           
9988e4ba66ce159c60fcf384d153cd0819729c109768529d978dd6463fa69393  specs/fpga/fifo.t27                   
files $

recorded 2026-10-07 17:36 UTCreal 27.0 sshown 26.6 sexit codes 0 0 0 0

$ t27c test-report specs/fpga/fifo.t27 --specs-dir specs | sed -n '1,7p' $ sed -i '' 's/(state.head_ptr + 1) % cfg.depth/(state.head_ptr + 3) % cfg.depth/' specs/fpga/fifo.t27 && git diff -U0 specs/fpga/fifo.t27 | tail -n 2 $ t27c test-report specs/fpga/fifo.t27 --specs-dir specs | sed -n '1,7p' $ git checkout specs/fpga/fifo.t27 && sha256sum specs/fpga/fifo.t27

Staged: the prompt and the typing. Real: every byte the commands printed, at the time they printed it. Any silence longer than 2 s is shown for 2 s, and the title bar says so while it happens. Edited: home directory shown as ~.

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