digitalmars.D.bugs - [Issue 8637] New: Enforcement and purity
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http://d.puremagic.com/issues/show_bug.cgi?id=8637
Summary: Enforcement and purity
Product: D
Version: unspecified
Platform: All
OS/Version: All
Status: NEW
Severity: normal
Priority: P2
Component: Phobos
AssignedTo: nobody puremagic.com
ReportedBy: monarchdodra gmail.com
--- Comment #0 from monarchdodra gmail.com 2012-09-10 02:58:42 PDT ---
The argument taken by enforce must be "castable to bool", so the the
implementation can do the cast. However, enforce is declared pure, so if the
cast operator is not pure, the compilation fails:
--------
import std.regex;
import std.exception;
void main()
{
auto m = match("hello world", regex("world"));
assert(m); //<- Fine
enforce(m); //Here
}
--------
Error: pure function 'enforce' cannot call impure function '~this'
Error: pure function 'enforce' cannot call impure function 'opCast'
--------
The messages come from:
--------
T enforce(T)(T value, lazy const(char)[] msg = null, string file = __FILE__,
size_t line = __LINE__) safe pure
{
if (!value) bailOut(file, line, msg);
return value;
}
--------
"if(!value)": This makes an impure call to opCast.
"enforce(T)(T value..." This uses pass by value, and makes an impure call to
the destructor
I have no idea what a good fix would be. Regarding pass by value, wouldn't this
be a textbook example of using "auto ref" with "auto return"? I have no idea...
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Kenji Hara <k.hara.pg gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Version|unspecified |D2
--- Comment #1 from Kenji Hara <k.hara.pg gmail.com> 2012-09-10 08:14:02 PDT ---
(In reply to comment #0)
The argument taken by enforce must be "castable to bool", so the the
implementation can do the cast. However, enforce is declared pure, so if the
cast operator is not pure, the compilation fails:
[snip]
--------
Error: pure function 'enforce' cannot call impure function '~this'
Error: pure function 'enforce' cannot call impure function 'opCast'
--------
The cause might be the explicit annotation with pure.
The messages come from:
--------
T enforce(T)(T value, lazy const(char)[] msg = null, string file = __FILE__,
size_t line = __LINE__) safe pure
{
if (!value) bailOut(file, line, msg);
return value;
}
--------
"if(!value)": This makes an impure call to opCast.
"enforce(T)(T value..." This uses pass by value, and makes an impure call to
the destructor
I have no idea what a good fix would be. Regarding pass by value, wouldn't this
be a textbook example of using "auto ref" with "auto return"? I have no idea...
The strict pure annotation is introduced by the pull #263.
https://github.com/D-Programming-Language/phobos/pull/263
As you can see, the pure annotations were just for the documentation. At this
point, impure destructor had not been considered at all in the discussion.
Then, now, the pure annotation causes this problem, so I think we should remove
it and rely on the pure attribute inference.
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http://d.puremagic.com/issues/show_bug.cgi?id=8637 --- Comment #2 from monarchdodra gmail.com 2012-09-10 08:43:02 PDT --- If that is the fix, I can make the pull request. Do you want me to do it, or are you on it? -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Sep 10 2012
http://d.puremagic.com/issues/show_bug.cgi?id=8637 --- Comment #3 from Kenji Hara <k.hara.pg gmail.com> 2012-09-10 08:49:24 PDT --- (In reply to comment #2)If that is the fix, I can make the pull request. Do you want me to do it, or are you on it?Of course I would welcome your contribution. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Sep 10 2012
http://d.puremagic.com/issues/show_bug.cgi?id=8637
monarchdodra gmail.com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
AssignedTo|nobody puremagic.com |monarchdodra gmail.com
--- Comment #4 from monarchdodra gmail.com 2012-09-10 08:57:48 PDT ---
Will commit fix myself then.
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Sep 10 2012
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Jonathan M Davis <jmdavisProg gmx.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |jmdavisProg gmx.com
--- Comment #5 from Jonathan M Davis <jmdavisProg gmx.com> 2012-09-10 09:07:50
PDT ---
Both the annotation for pure and safe need to go, because T's destructor and
opCast could be impure or non- safe. When the explicit annotations were added,
clearly the destructor and opCast were not taken into account, since they're
not called directly and are easily forgotten.
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http://d.puremagic.com/issues/show_bug.cgi?id=8637 --- Comment #6 from Kenji Hara <k.hara.pg gmail.com> 2012-09-10 09:15:20 PDT --- (In reply to comment #5)Both the annotation for pure and safe need to go, because T's destructor and opCast could be impure or non- safe. When the explicit annotations were added, clearly the destructor and opCast were not taken into account, since they're not called directly and are easily forgotten.Oh, that's right. We should remove both 'pure' and ' safe', and need to depends on fully attribute inference. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Sep 10 2012
http://d.puremagic.com/issues/show_bug.cgi?id=8637
Dmitry Olshansky <dmitry.olsh gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |dmitry.olsh gmail.com
--- Comment #7 from Dmitry Olshansky <dmitry.olsh gmail.com> 2012-09-10
12:44:17 PDT ---
Sorry, it had regex somewhere in description so I jumped in ;)
https://github.com/D-Programming-Language/phobos/pull/783
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http://d.puremagic.com/issues/show_bug.cgi?id=8637 --- Comment #8 from monarchdodra gmail.com 2012-09-10 13:59:53 PDT --- Darn! Kidding asside, thanks. BTW, I just made touch on std.regex itself. Seems like you may have wanted to know: https://github.com/D-Programming-Language/phobos/pull/784 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Sep 10 2012
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monarchdodra gmail.com changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
--- Comment #9 from monarchdodra gmail.com 2012-09-11 10:23:36 PDT ---
Fixed by Dmitry in
https://github.com/D-Programming-Language/phobos/pull/783
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Sep 11 2012