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Scanf.scanf works differently around "@" char in 4.01.0+dev2 #5605

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vicuna opened this issue May 3, 2012 · 3 comments
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Scanf.scanf works differently around "@" char in 4.01.0+dev2 #5605

vicuna opened this issue May 3, 2012 · 3 comments
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bug duplicate high-priority stdlib

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@vicuna
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vicuna commented May 3, 2012

Original bug ID: 5605
Reporter: furuse
Assigned to: @protz
Status: closed (set by @xavierleroy on 2013-08-31T10:49:13Z)
Resolution: fixed
Priority: high
Severity: major
Category: standard library
Duplicate of: #5380

Bug description

In OCaml 3.12.1,

Scanf.scanf "%S %S@\n" (fun x y -> (x,y));;

"hello" "world"

  • : string * string = ("hello", "world")

In OCaml 4.01.0+dev2_2012-04-17,

Scanf.scanf "%S %S@\n" (fun x y -> (x,y));;

"hello" "world"
Exception:
Scanf.Scan_failure
"scanf: bad input at char number 27: ``looking for '@', found '\n'''".

I do not know it is a bug or not, but this difference causes trouble at ocaml setup.ml -build in OASIS.

An interesting thing is that the following works fine:

Scanf.scanf "%S %S %s@\n" (fun x y z -> (x,y,z));;

"hello" "world" bye

  • : string * string * string = ("hello", "world", "bye")
@vicuna
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vicuna commented May 3, 2012

Comment author: @ygrek

duplicate of #5380

@vicuna
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vicuna commented May 3, 2012

Comment author: furuse

By reading the comment in scanf.mli, I understand the current behaviour is correct wrt it. So, I think it is a bug of OASIS caused by a buggy implementation of the old scanf.ml.

(** Scanning indications appear just after the string conversions [%s]
and [%[ range ]] to delimit the end of the token. A scanning
indication is introduced by a [@] character, followed by some
plain character [c]. It means that the string token should end
just before the next matching [c] (which is skipped). If no [c]
character is encountered, the string token spreads as much as
possible. For instance, ["%s@\t"] reads a string up to the next
tab character or to the end of input. If a [@] character appears
anywhere else in the format string, it is treated as a plain character.

@vicuna
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vicuna commented May 3, 2012

Comment author: @damiendoligez

This is a known bug in oasis, and as far as I know, it was fixed a few months ago:

https://forge.ocamlcore.org/tracker/index.php?func=detail&aid=1067&group_id=54&atid=291

@vicuna vicuna closed this as completed Aug 31, 2013
@vicuna vicuna mentioned this issue Aug 2, 2013
Closed
@vicuna vicuna added the bug label Mar 20, 2019
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@vicuna