Joseph Ferano
9a820d86cd
The script is in tools/ rather than thrown away, because two lanes are
writing Flan in the old spelling right now and their files need the same
pass at merge.
It works on forms, not on text: a keyword becomes a dot only where it sits
in a field-label position inside a brace, so an enum member in value
position, a map key inside an EDN string and a type-position {K V} are all
left alone. :keys keeps its colon -- it names no field.
62 lines
2.2 KiB
Plaintext
62 lines
2.2 KiB
Plaintext
;;;; The cleanup paths nothing was watching.
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;;;;
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;;;; Found by mutation testing: each of the six claims below could be broken in
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;;;; lib/check.ml, lib/emit.ml or runtime/flan_rt.c and the whole suite stayed
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;;;; green. Every case here is one a plausible wrong version gets wrong, and
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;;;; the numbers differ per failure so a single wrong answer names its cause.
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(defstruct Missing [id i32])
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(defstruct Other [id i32])
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(defvar log i64)
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(defvar order i64)
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(defvar seen i64)
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(defn note [n i64] (set order (+ (* order 10) n)))
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;;; (1) An early return must run the defers registered above it, and (2) it
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;;; must run them innermost-first. A defer that (8) *calls* something is the
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;;; case that puts a guard inside the defer, on the transfer path.
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(defn early [] i64
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(defer (note 1))
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(defer (note 2))
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(return 7)
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0)
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;;; (5) A transfer out of a handler-bind has to pop its frames on the way past,
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;;; and (6) a handler-bind with two clauses has to pop both, innermost-first.
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;;; If either leaks, the stack keeps a frame pointing into a function that has
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;;; gone, and the next signal calls into it.
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(defn deep [] i32 (signal (Missing {.id 1})) 0)
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(defn leaky [] i32
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(restart-case
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(handler-bind [(Other [c] (set seen (+ seen 1000)))
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(Missing [c] (invoke-restart 'skip))]
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(deep))
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(skip [] 42)))
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;;; (7) Once a handler has answered a signal by transferring, the walk stops:
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;;; an outer handler of the same type must not also run.
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(defn nested [] i32
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(restart-case
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(handler-bind [(Missing [c] (set seen (+ seen 100)))]
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(handler-bind [(Missing [c] (invoke-restart 'stop))]
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(deep)))
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(stop [] 5)))
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(defn main [] i32
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(print (early)) (println "") ; 7
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(print order) (println "") ; 21 — innermost first, both ran
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(print (leaky)) (println "") ; 42
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;; The handler stack must be empty again. If a frame leaked, this signal
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;; reaches it and seen moves.
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(deep)
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(print seen) (println "") ; 0
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(set seen 0)
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(print (nested)) (println "") ; 5
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(print seen) (println "") ; 0 — the outer handler did not run
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(print log) (println "") ; 0
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0)
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