• d-bugmail puremagic.com Jun 13 2009
• d-bugmail puremagic.com Jul 15 2009

d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=3066

           Summary: Array operation without a slice as the lvalue
                    accepted, bad codegen
           Product: D
           Version: 1.045
          Platform: x86_64
               URL: http://www.digitalmars.com/d/1.0/arrays.html
        OS/Version: Linux
            Status: NEW
          Keywords: accepts-invalid, diagnostic, spec, wrong-code
          Severity: major
          Priority: P3
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: matti.niemenmaa+dbugzilla iki.fi


The below code compiles, but shouldn't: array operations can't be used as
initializers according to the spec, they need a slice as the lvalue.

void main() {
    auto x = [2,3,4];
    auto y = [1,1,1];
    auto z = x[] - y[];
    assert (z == [1,2,3]);
}

The assertion fails: z becomes a dynamic array with length 0 and an invalid
pointer.

A similarly incorrect array results with most other operators. Using +,
however, gives the following strange diagnostic:

foo.d(5): Error: Array operation x[] + y[] not implemented

This makes no sense, since x[] + y[] itself is perfectly fine as well as
implemented.

Replacing 'auto z' with 'int[3] z' makes all cases succeed, but that
contradicts the spec. IMHO there's no reason why using array operations as
initializers should be invalid but that's what the spec currently says; added
the 'spec' keyword to this in the hopes that this is legalized.

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d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=3066


Kyle Foley <k-foley onu.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |k-foley onu.edu




--- Comment #1 from Kyle Foley <k-foley onu.edu>  2009-07-15 06:51:21 PDT ---
I have recently discovered some bugs that are related to this

---

import std.stdio;

int main()
{
    int[] a = [1, 2, 3][];

    int[] b = a[] + 4;
    writeln("-> ", b); // -> 1 2 3 0 1935766371 1768515939 1764585331

    int[] c;
    c[] = a[] + 4;
    writeln("-> ", c); // -> 

    c = [1, 1, 1][];
    c[] = a[] + 4;
    writeln("-> ", c); // -> 5 6 7

    c = [0][];
    c[] = a[] + 4;
    writeln("-> ", c); // -> 5

    c = a[] + 4;
    writeln("-> ", c); // -> 1 2 3 0 1935766371 1768515939 1764585331

    int[3] d = a[] + 4; // this is ok
    writeln("-> ", d); // -> 5 6 7

    int[3] e = [1, 2, 3];
    int[3] f = [5, 6, 7];
    //writeln( "-> ", e[] + f[] ); // Compile Error -- Error: Array operation
e[] + f[] not implemented
    // yet, this works:
    writeln( "-> ", e.dup[] += f[] ); // -> 6 8 10

    return 0;
}

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