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digitalmars.D.bugs - [Issue 1399] New: Wrapping a case statement in a version statement gives a shadowing declaration error.

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1399

           Summary: Wrapping a case statement in a version statement gives a
                    shadowing declaration error.
           Product: D
           Version: 1.019
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: aziz.kerim gmail.com


When compiling the snippet below with -version=D2 I get the following error:
"Error: shadowing declaration func.a is deprecated"

void func()
{
  switch(1)
  {
  case 1:
    auto a = 2;
    break;
  version(D2)
  {
  case 2:
    auto a = 2; // error
    break;
  }
  default:
  }
}


--
Aug 04 2007
next sibling parent BCS <ao pathlink.com> writes:
Reply to d-bugmail puremagic.com,


 http://d.puremagic.com/issues/show_bug.cgi?id=1399
 
 Summary: Wrapping a case statement in a version statement
 gives a
 shadowing declaration error.
 Product: D
 Version: 1.019
 Platform: PC
 OS/Version: Linux
 Status: NEW
 Keywords: rejects-valid
 Severity: normal
 Priority: P2
 Component: DMD
 AssignedTo: bugzilla digitalmars.com
 ReportedBy: aziz.kerim gmail.com
 When compiling the snippet below with -version=D2 I get the following
 error: "Error: shadowing declaration func.a is deprecated"
 
 void func()
 {
 switch(1)
 {
 case 1:
 auto a = 2;
 break;
 version(D2)
 {
 case 2:
 auto a = 2; // error
 break;
 }
 default:
 }
 }


Invalid: version blocks are not a naming scope.

Well it might be a bug because it should be a "can't have two a's" error, 
not a shadowing error
Aug 05 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1399


smjg iname.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |smjg iname.com
           Keywords|rejects-valid               |diagnostic





Indeed, the bug is that it delivers the wrong error message.  The correct
message would be

bz1399.d(11): Error: declaration bz1399.func.a is already defined

However, if I get rid of the version block, the code compiles without error,
but this is due to issue 603.

And Nazo, please don't quote the entire message when replying.


--
Aug 06 2007
prev sibling next sibling parent reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1399






I think I can explain how the compiler understands the code I provided. Stewart
has observed correctly, that when you remove the version block the code
compiles without errors. This is because every case and default block
introduces a new scope (the switch block has its own scope as well.)

The two case blocks are similar to this code:

void func()
{
  // This is valid code.
  {
    auto a = 0;
  }
  {
    auto a = 0;
  }
}

The problem arises when you wrap the second case statement into a version
block, because then the version block plus the nested case block is contained
by the first case block. The reason for this is that the parses parses every
statement until it hits another case or default block.

The code with the version block would thus be seen by the compiler as:

void func()
{
  {
    auto a = 0;
  {
    auto a = 0; // Error: shadowing outer a
  }
  }
}

The following code generates the same error:

switch (1)
{
auto a = 0;
case 1:
  auto a = 1; // Error: shadowing declaration
default:
}


--
Aug 07 2007
parent BCS <ao pathlink.com> writes:
This might have something to do with an error I keep running into where if 
you have a static if statement with nothing but a case label, then sometime 
things go strange. I don't have a test case handy but I'll try to work one 
up sooner or later.
Aug 07 2007
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1399






You actually don't need the version block to demonstrate this bug. This will do
as well:

switch(1)
{
case 1:
  auto a = 1;
{
case 2:
  auto a = 2;
}
default:
}

By the way, regarding the last code snippet I showed in my previous post: this
isn't a bug, the compiler behaves correctly.


--
Aug 07 2007
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1399






That's different, because when it isn't the body of a CC statement, { } opens a
new scope.  In this case, the compiler is behaving correctly according to the
spec as I try it.

bz1399c4.d(8): Error: shadowing declaration bz1399c4.main.a is deprecated


--
Aug 07 2007