v3.5.1

Nothing about the language changed. The version number here tracks the
accepted language, the diagnostics and the command line, and this release
touches none of them: it is the documentation pass after 3.5.0 plus four dead
symbols removed from the runtime. It is recorded because a release with nothing
in it for a user is worth saying so plainly rather than dressing up.

What the documentation pass found is the part worth reading, and it is in
doc/history.md under The release that checked itself:
three defects that cutting 3.5.0 surfaced and no gate could see, a seed that
named the machine that made it, and two documents claiming an oracle —
AddressSanitizer over compiled Pascal — that has never existed.

Removed

• Four runtime symbols that nothing called: pas_index_error,
  pas_range_error, pas_disc_error and pas_length_error, the two-word
  forms kept as wrappers when ADR-0293 gave every trap its own position. The
  3.5.0 reseed made them dead — the seed calls only the _at forms — and
  doc/sop.md §7 had said since ADR-0293 that they could go at the next
  reseed.

  The one compatibility note in this release: IR emitted by v3.4.0 or
  earlier calls the two-word forms, so such a module will not link against
  this runtime. Anything emitted by 3.5.0 or later is unaffected, and the
  release archive ships the compiler and the runtime together. Recompile the
  source rather than relinking old .ll.

Fixed

• A trap in a seed-built compiler names its position. The wrappers passed
  none, so a crash in build/bin/pascalc — which procedure-coverage and
  fuzz watch for — reported where nothing. This is a fact about building the
  compiler rather than about using it.