http://d.puremagic.com/issues/show_bug.cgi?id=5862

           Summary: case statement allows runtime values
           Product: D
           Version: D2
          Platform: Other
        OS/Version: Windows
            Status: NEW
          Keywords: accepts-invalid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: andrej.mitrovich@gmail.com


--- Comment #0 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2011-04-19 13:22:50 PDT ---
int foo(ref int y)
{
   y = 5;
   return y;
}

void main()
{
   int x = 1;
   int y = 2;

   switch (x = foo(y))
   {
       case y:  // <- should not be allowed
           writeln("x == y");
       default:
   }

   assert(x == 5);
   assert(y == 5);
}

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--- Comment #2 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2011-06-19 07:26:37 PDT ---
I don't really know why it wouldn't be allowed, unless there's some optimization technique that depends on it.

However:

void main()
{
    int x;
    int y;

    switch (x)
    {
        case y + 1:
            break;

        default:
    }
}

Error: variable y cannot be read at compile time
Error: case must be a string or an integral constant, not y + 1

Either runtime values are fully supported, or they are not. Some decision has to be made for this if the compiler and TDPL don't agree with each other. Should I open up a new thread in the NGs to discuss this?

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bearophile_hugs@eml.cc changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bearophile_hugs@eml.cc


--- Comment #3 from bearophile_hugs@eml.cc 2011-06-19 07:28:44 PDT ---
I think this is a valid bug.

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Stewart Gordon <smjg@iname.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
                URL|                            |http://www.digitalmars.com/
                   |                            |d/1.0/statement.html#CaseSt
                   |                            |atement
                 CC|                            |smjg@iname.com
           Platform|Other                       |All
         Resolution|INVALID                     |


--- Comment #4 from Stewart Gordon <smjg@iname.com> 2011-06-19 10:37:14 PDT ---
http://www.digitalmars.com/d/1.0/statement.html#CaseStatement
"The case expressions must all evaluate to a constant value or array. They must
be implicitly convertible to the type of the switch Expression."

http://www.digitalmars.com/d/2.0/statement.html#CaseStatement
"The case expressions must all evaluate to a constant value or array, or a
runtime initialized const or immutable variable of integral type. They must be
implicitly convertible to the type of the switch Expression."

Strangely, 1.068 (Win32) correctly rejects the code.

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