Joseph Ferano
aa0b799bb6
flan_dev_global hands back the allocation it made the first time a name was asked for, and compares the size it recorded against the size it is asked for. Nothing exercised the comparison: v5 is v4 with extra as an i32, loaded on top of v3, and what it does is abort the process — so it gets a host run of its own. The message is asserted alongside the exit status, because a process that died for some other reason is not this guard firing and the status alone cannot tell them apart.
30 lines
1.1 KiB
Plaintext
30 lines
1.1 KiB
Plaintext
;;;; v5 is v4 with one difference: [extra] is an i32 rather than an i64.
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;;;;
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;;;; [extra] does not exist in the host — v3 introduced it at run time, so its
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;;;; storage was allocated by runtime/flan_dev.c the first time a module asked
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;;;; for it, and every later module that mentions the name is handed back that
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;;;; same allocation. Handing it back for a differently shaped type is layout
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;;;; drift: the new body would read and write at offsets the old allocation was
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;;;; never laid out for, and nothing downstream could ever say so. The registry
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;;;; compares the size it recorded against the size it is asked for and aborts
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;;;; instead — retyping a var needs a restart, and this is the file that says
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;;;; the guard is real.
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;;;;
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;;;; Loaded on top of v3, and never alongside v4: the process it aborts is the
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;;;; whole of the test.
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(defvar counter i64)
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(defvar extra i32)
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(defn helper [x i64] i64 (* x 2))
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(defn added [] i32
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(set extra (+ extra 100))
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extra)
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(defn bump [] i64
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(println "v5")
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(set counter (+ counter (i64 (added))))
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(helper counter))
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(defn outer [] i64 (bump))
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