http://d.puremagic.com/issues/show_bug.cgi?id=4539

           Summary: Refuse assignment to string literal
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Keywords: accepts-invalid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: bearophile_hugs@eml.cc


--- Comment #0 from bearophile_hugs@eml.cc 2010-07-31 04:26:35 PDT ---
dmd 2.047 compiles this code, but string literals can't be lvalues:

void main() {
    "hello" = "red";
}

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

           What    |Removed                     |Added
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                 CC|                            |andrej.mitrovich@gmail.com


--- Comment #1 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2010-07-31 07:27:57 PDT ---
I just found this by accident on the compiler docs page:

http://www.digitalmars.com/d/2.0/dmd-windows.html

"
Differences between Windows and Linux versions

    * String literals are read-only under Linux. Attempting to write to them
will cause a segment violation.
"

Maybe this is relevant?

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--- Comment #2 from bearophile_hugs@eml.cc 2010-07-31 08:48:12 PDT ---
I think that's not relevant, I think that refers to changing the content of a variable initialized with a string literal (plus cast to mutable).

But the code I have shown is meaningless, because a string can't be a lvalue. It's like doing:

void main() {
    5 = 7;
}

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--- Comment #3 from Andrej Mitrovic <andrej.mitrovich@gmail.com> 2010-07-31 09:18:53 PDT ---
Yeah, it does not make sense at all. But it gets worse:

import std.stdio;

void main() {
    "hello" = "red";
    string x = "hello";
    writeln(x);
}

Writes "red"

That's not good. :)

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Don <clugdbug@yahoo.com.au> changed:

           What    |Removed                     |Added
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                 CC|                            |clugdbug@yahoo.com.au
           Severity|normal                      |major


--- Comment #4 from Don <clugdbug@yahoo.com.au> 2010-07-31 17:30:23 PDT ---
(In reply to comment #3)
> Yeah, it does not make sense at all. But it gets worse:
> 
> import std.stdio;
> 
> void main() {
>     "hello" = "red";
>     string x = "hello";
>     writeln(x);
> }
> 
> Writes "red"
> 
> That's not good. :)

Ouch!

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nfxjfg@gmail.com changed:

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                 CC|                            |nfxjfg@gmail.com


--- Comment #5 from nfxjfg@gmail.com 2010-07-31 18:43:05 PDT ---
This segfaults on the far superior Linux (dmd v2.046), so yes, it's probably because OPTLINK can't do read-only sections.

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--- Comment #6 from bearophile_hugs@eml.cc 2010-10-29 09:55:19 PDT ---
A related bug found by denis spir:

auto p = &"hello";

String literals aren't lvalues, so you can't take their address. Just as you can't tale the address of a decimal literal:

auto q = &(1);

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

           What    |Removed                     |Added
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           Keywords|                            |patch
                 CC|                            |k.hara.pg@gmail.com


--- Comment #7 from Kenji Hara <k.hara.pg@gmail.com> 2011-04-27 04:16:32 PDT ---
Patch posted: https://github.com/D-Programming-Language/dmd/pull/46

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kennytm@gmail.com changed:

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                 CC|                            |bugzilla@kyllingen.net


--- Comment #8 from kennytm@gmail.com 2011-04-29 07:04:05 PDT ---
*** Issue 4309 has been marked as a duplicate of this issue. ***

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Walter Bright <bugzilla@digitalmars.com> changed:

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                 CC|                            |bugzilla@digitalmars.com


--- Comment #9 from Walter Bright <bugzilla@digitalmars.com> 2011-06-04 22:55:03 PDT ---
(In reply to comment #7)
> Patch posted: https://github.com/D-Programming-Language/dmd/pull/46

See github for problems with the patch.

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