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digitalmars.D.bugs - [Issue 10516] New: Array length is not checked when array is a manifest constant

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=10516

           Summary: Array length is not checked when array is a manifest
                    constant
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: andrej.mitrovich gmail.com



18:38:31 PDT ---
-----
void main()
{
    enum HexSize = 5;

    // note: smaller initializer count
    enum char[HexSize] srcHex = "1234";

    char[HexSize] tgtHex = "12345";

    // should error with: lengths don't match for array copy
    assert(tgtHex[0 .. 4] == srcHex);
}
-----

$ dmd test.d

 core.exception.AssertError test(11): Assertion failure


The problem here is that the runtime allowed the left-hand side and right-hand
side arrays to be compared even though their lengths do not match.

If you convert the source array from a manifest constant into a regular array
(by removing enum) then the error is proper:

-----
void main()
{
    enum HexSize = 5;

    // note: smaller initializer count
    /* enum */ char[HexSize] srcHex = "1234";  

    char[HexSize] tgtHex = "12345";

    assert(tgtHex[0 .. 4] == srcHex);
}
-----

$ dmd test.d

 object.Error: lengths don't match for array copy, 5 = 4


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parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=10516


Andrej Mitrovic <andrej.mitrovich gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID



19:01:18 PDT ---

 -----
 void main()
 {
     enum HexSize = 5;
 
     // note: smaller initializer count
     /* enum */ char[HexSize] srcHex = "1234";  
 
     char[HexSize] tgtHex = "12345";
 
     assert(tgtHex[0 .. 4] == srcHex);
 }
 -----
 
 $ dmd test.d

 object.Error: lengths don't match for array copy, 5 = 4




Actually this test-case is invalid because the error is thrown in the
initializer line, not the comparison line.

And another thing I just realized is that it's perfectly ok to compare static
arrays of non-matching sizes, which makes the whole report invalid.. but I
don't understand why this is allowed:

void main()
{
    char[5] srcHex = "12345";
    char[3] tgtHex = "123";
    assert(srcHex == tgtHex);
}

$ dmd test.d

 core.exception.AssertError test(5): Assertion failure


I would have hoped to get a length mismatch error, or even a compile-time
error. Oh well..

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