Joseph Ferano
96ab4c9cf0
print-str, print-i64, print-f64, print-bytes, print-line and newline leave the prelude. print and println are the whole printing surface now, and print is the better call at every one of the sites that used them: it is the same structural walk without the newline, so the no-newline case the family was kept for is covered, and it takes the value as it is. The old print-i64 forced an explicit (i64 x) at every call site, because this language widens nothing implicitly; that cast is gone from 127 places. Dropping it moves one answer. hash-grid returns u64, and the cast through the signed printer showed sand-headless's hash as -2851001042534928384. print routes a u64 through flan_u64_to_bytes, so it now prints 15595743031174623232 — the same 64 bits, read as the unsigned number they are. The pinned expectation follows the correction. test-flan-dev.el and test_session.ml both reached for print-line as "a name the prelude has"; they reach for rand-seed instead.
22 lines
1.2 KiB
Plaintext
22 lines
1.2 KiB
Plaintext
;;;; Signedness, which nothing in the corpus was exercising.
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;;;;
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;;;; Found by mutation testing: emit.ml chooses ashr vs lshr and slt vs ult
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;;;; from the operand's type, and both choices could be hardcoded to one arm
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;;;; with the whole suite still green — because no program shifted a negative
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;;;; integer right, and none compared an unsigned value above 2^31.
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(defn main [] i32
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;; An arithmetic shift keeps the sign. A logical one on -8 gives a number
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;; near 2^63, which is the wrong answer that looks like a huge right one.
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(print (>> (i64 -8) 1)) (println "") ; -4
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(print (>> (i64 -1) 40)) (println "") ; -1, still, however far it goes
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;; And unsigned stays unsigned: 3000000000 has its top bit set, so a signed
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;; compare reads it as negative and answers the other way on every operator.
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(let [big (bit-or (<< (u32 1) 31) (u32 1000))] ; 2^31 + 1000
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(println (if (< big (u32 5)) "wrong: signed compare" "big is not small"))
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(println (if (> big (u32 5)) "big is large" "wrong: signed compare"))
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;; The same value through >>, which is logical on an unsigned type: a
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;; signed shift here would keep the top bit and answer near 2^31 again.
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(print (>> big 31)) (println "")) ; 1
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0)
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