http://d.puremagic.com/issues/show_bug.cgi?id=3748

           Summary: inout does not work properly
           Product: D
           Version: 2.039
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: major
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: schveiguy@yahoo.com


--- Comment #0 from Steven Schveighoffer <schveiguy@yahoo.com> 2010-01-28 05:06:44 PST ---
Created an attachment (id=558)
file to test whether inout is properly implemented

inout as defined by DIP2 is not implemented properly on dmd 2.039.  Attached is a testing program that should be used to determine if inout is properly implemented.  I tried to include every subtle detail that I could on inout, but I'm not sure that I got them all.  If the compiler passes this test, inout should be ready for most uses.

Since half of the definition of inout is what *doesn't* compile, I have included multiple errors in the file.  Because of the nature of compiler errors, each error can be individually enabled or disabled using version statements, a la error1, error2, etc.

When no error statements are enabled, the program should compile correctly. There is no need to run the program, since all asserts are static.

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kennytm@gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
 Attachment #558 is|0                           |1
           obsolete|                            |


--- Comment #1 from kennytm@gmail.com 2011-04-26 11:20:36 PDT ---
Created an attachment (id=950)
Fixed some minor syntax error.

Fixed the position of ';' on line 22.
Added back the missing is() on lines 48 and 50.

(Just a note: as of commit 48950d4ce371316184e2 (2.052) DMD still cannot
compile this file successfully.)

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Kenji Hara <k.hara.pg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tomash.brechko@gmail.com


--- Comment #2 from Kenji Hara <k.hara.pg@gmail.com> 2011-08-31 08:07:52 PDT ---
*** Issue 4968 has been marked as a duplicate of this issue. ***

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Kenji Hara <k.hara.pg@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch


--- Comment #3 from Kenji Hara <k.hara.pg@gmail.com> 2011-08-31 08:15:03 PDT ---
https://github.com/D-Programming-Language/dmd/pull/359

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--- Comment #4 from Kenji Hara <k.hara.pg@gmail.com> 2011-08-31 10:40:24 PDT ---
My patch doesn't forbid to declare inout variable outside inout function. It is treated same as const variable, even with my patch.

I think it is debatable thing.

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--- Comment #5 from Steven Schveighoffer <schveiguy@yahoo.com> 2011-08-31 12:11:15 PDT ---
it is not debateable.  The issue is, when inside an inout-enabled function, all inout variables are *assignable* from other inout variables.

So for example, if you have:

inout(int) * globalvar;

inout(int)* foo(inout(int)* x)
{
   return globalvar;
}

void main()
{
   int x;
   auto y = foo(&x);
}

what type is y?  inout(T) is changed to just T in this scenario, since the constancy factor is mutable, so essentially, you now have a mutable pointer to what is treated as const as you say.

The type system *must* prevent non-local variables (i.e. variables not on the stack) from being inout.  Otherwise, you cannot make guarantees about inout.

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Walter Bright <bugzilla@digitalmars.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |bugzilla@digitalmars.com
         Resolution|                            |FIXED


--- Comment #6 from Walter Bright <bugzilla@digitalmars.com> 2011-10-01 22:10:12 PDT ---
https://github.com/D-Programming-Language/dmd/commit/07f719e5bd882b0e66e9759ed29319e2be93ef3c

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--- Comment #7 from Steven Schveighoffer <schveiguy@yahoo.com> 2011-10-05 06:31:35 PDT ---
Created an attachment (id=1035)
Corrected some errors that were previously hard to detect because inout didn't
work

uploaded a fixed version of testinout.d

error8 and error11 still compile, so this isn't completely resolved, but inout is definitely is usable.

I will open a new bug for that, as this is a single problem with inout (allowing inout variables anywhere, not just as auto variables of inout functions).

Note that Kenji stated those holes were still present.  But this is definitely a huge step forward.

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--- Comment #8 from Steven Schveighoffer <schveiguy@yahoo.com> 2011-10-05 06:49:38 PDT ---
See new bug 6770

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--- Comment #9 from Kenji Hara <k.hara.pg@gmail.com> 2011-10-05 17:41:38 PDT ---
For fixing error8 and error11. https://github.com/D-Programming-Language/dmd/pull/433

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