I committed a patch yesterday that I thought was a very good first
start. However, this morning I've found some holes in it that make
things look very bleak again.
What my patch did was simply ensure one thing -- that whenever an
alias was taken, it was verified that it was 'rooted' in a thing
On 6/7/11 12:59 AM, Marijn Haverbeke wrote:
Unfortunately, there's this hole I mentioned before. What this
analysis guarantees is that the location pointed to by an alias will
always hold a value of type X — if you reassign to it, the alias will
still be valid. Except when going through a tag
Sorry if I'm misunderstanding, but I thought I covered that in my previous
email--we have to forbid access to the expression in an alt statement
inside the case blocks.
Your proposal seems to assume you'd only ever directly alias locals.
That is a possible solution, but it seems excessively
On 07/06/2011 7:40 AM, Marijn Haverbeke wrote:
Sorry if I'm misunderstanding, but I thought I covered that in my previous
email--we have to forbid access to the expression in an alt statement
inside the case blocks.
Your proposal seems to assume you'd only ever directly alias locals.
That is a
On 11-06-07 01:05 PM, Florian Weimer wrote:
AFAICS, Ada has a somewhat similar issue (the affected types have
discriminants with defaults). Over there, the prevalent feeling
seems to be that destructive update of objects of types with
discriminants with defaults is to blame, and not aliasing.
Indeed. This was always going to be one of the trickiest part of the design. In
this latest iteration, we've only been attacking it for a couple of days. We
can't expect a solution to just pop out that easily; we will have to bang our
heads against it for a while. And we've already seen a
(1) Handing out aliases to local variables and function parameters
(directly, not substructures thereof) is always safe. The calling function
is the only one that can possibly provide access its own locals, and it's
suspended for the duration of the call.
Except for upvars. 'for each' bodies
On 03/06/2011 7:29 AM, Marijn Haverbeke wrote:
[This is just a rambing e-mail outlining some problems I'm running
into. Though I am stressing these problems to make sure they are not
glossed over, I'm *not* suggesting we give up aliases or anything like
that.]
Much appreciated; if something's
On 11-06-03 01:51 PM, Patrick Walton wrote:
Thoughts?
I like the line of reasoning; let me try phrasing in a slightly more
terse/pithy fashion:
Alias-formation must preserve unique ownership of the referent
IOW an alias is assumed to be a form of unique access to its immediate
referent
On 6/3/11 2:07 PM, Graydon Hoare wrote:
On 11-06-03 01:51 PM, Patrick Walton wrote:
Thoughts?
I like the line of reasoning; let me try phrasing in a slightly more
terse/pithy fashion:
Alias-formation must preserve unique ownership of the referent
Right, that's a good way to put it.
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