[Issue 602] New: Compiler allows a goto statement to skip an initalization

Nov 26, 2006

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November 26, 2006

[Issue 602] New: Compiler allows a goto statement to skip an initalization

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http://d.puremagic.com/issues/show_bug.cgi?id=602

           Summary: Compiler allows a goto statement to skip an
                    initalization
           Product: D
           Version: 0.175
          Platform: PC
               URL: http://www.digitalmars.com/d/statement.html#GotoStatemen
                    t
        OS/Version: Windows
            Status: NEW
          Keywords: accepts-invalid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: smjg@iname.com


The spec for GotoStatement states:

"It is illegal for a GotoStatement to be used to skip initializations."

However, this code compiles:

----------
import std.stdio;

void main() {
    goto qwert;

    int yuiop = 42;

qwert:
    writefln(yuiop);
}
----------
4294112
----------

The spec doesn't comment on the use of goto to skip a declaration with no explicit initialization, but it has the same effect of bypassing the principle that all variables in D are initialized (unless this behaviour is overridden with a void).  In other words, this does the same:

----------
import std.stdio;

void main() {
    goto qwert;

    int yuiop;

qwert:
    writefln(yuiop);
}
----------

In both instances, a goto has been used to prevent a variable from being initialized.  Essentially, the compiler treats the code as being equivalent to:

----------
import std.stdio;

void main() {
    int yuiop = void;

    writefln(yuiop);
}
----------


--

http://d.puremagic.com/issues/show_bug.cgi?id=602 ------- Comment #1 from deewiant@gmail.com 2007-03-30 13:06 ------- Switch statements can also contain initializations prior to any case or default. This is either a symptom of this bug, or an enhancement request. I'll leave it here for now: void main() { switch (1) { int x; case 1: assert (x == x.init); } } --

http://d.puremagic.com/issues/show_bug.cgi?id=602 Matti Niemenmaa <matti.niemenmaa+dbugzilla@iki.fi> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |anteusz@freemail.hu --- Comment #2 from Matti Niemenmaa <matti.niemenmaa+dbugzilla@iki.fi> 2009-11-25 01:38:02 PST --- *** Issue 3549 has been marked as a duplicate of this issue. *** -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=602 Lars T. Kyllingstad <bugzilla@kyllingen.net> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bearophile_hugs@eml.cc --- Comment #3 from Lars T. Kyllingstad <bugzilla@kyllingen.net> 2010-08-17 09:51:02 PDT --- *** Issue 4667 has been marked as a duplicate of this issue. *** -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=602 Andrei Alexandrescu <andrei@metalanguage.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |ASSIGNED CC| |andrei@metalanguage.com Version|0.175 |D1 & D2 AssignedTo|nobody@puremagic.com |bugzilla@digitalmars.com -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=602 Kasumi Hanazuki <k.hanazuki@gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |destructionator@gmail.com --- Comment #4 from Kasumi Hanazuki <k.hanazuki@gmail.com> 2011-10-26 12:06:07 PDT --- *** Issue 6683 has been marked as a duplicate of this issue. *** -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=602 Martin Nowak <code@dawg.eu> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jlquinn@optonline.net --- Comment #5 from Martin Nowak <code@dawg.eu> 2013-10-31 10:15:09 PDT --- *** Issue 4101 has been marked as a duplicate of this issue. *** -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=602 --- Comment #6 from Martin Nowak <code@dawg.eu> 2013-10-31 10:31:38 PDT --- Any ideas how to implement this? It seems like an algorithm to distinguish this is non-trivial. I tested the following with clang and it gives me a correct warning (gcc 4.7.2 doesn't). goto.c:3:9:warning: variable 'test' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] int bug(int val) { if (val) goto Lno; int test = 0; Lno: {} return test; } -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=602 --- Comment #7 from Stewart Gordon <smjg@iname.com> 2013-11-03 17:17:25 PST --- It seems to me quite simple: If there is any variable that is in scope at the point of the label but not at the point of the goto statement, then we have a problem. Is there any case that this doesn't cover? -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

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