[Issue 3167] Passing result of a function call as ref argument no longer works
https://issues.dlang.org/show_bug.cgi?id=3167 Walter Bright bugzi...@digitalmars.com changed: What|Removed |Added Version|1.046 |D1 --
[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167 --- Comment #16 from Don clugd...@yahoo.com.au 2010-02-07 07:21:15 PST --- (In reply to comment #15) (In reply to comment #13) It is invalid code because you are taking a reference to the return value of a function. Functions return, by definition, rvalues. You cannot take a reference to an rvalue. But it used to work before. It didn't. It only seemed to work. In simple cases it happened to work, in more difficult cases it failed. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167 Walter Bright bugzi...@digitalmars.com changed: What|Removed |Added Status|NEW |RESOLVED Resolution||INVALID --- Comment #10 from Walter Bright bugzi...@digitalmars.com 2010-01-29 11:55:29 PST --- I'm going to mark this as invalid, as function return values should be rvalues, and rvalues cannot be references, even if the vagaries of the implementation make that possible. The reason is vagaries of the implementation, so it may work on one implementation but not another. Currently, whether it (used to) work or not also depended on the contents of the struct being returned. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167 Andrei Alexandrescu and...@metalanguage.com changed: What|Removed |Added CC||and...@metalanguage.com --- Comment #11 from Andrei Alexandrescu and...@metalanguage.com 2010-01-29 12:27:07 PST --- (In reply to comment #10) I'm going to mark this as invalid, as function return values should be rvalues, and rvalues cannot be references, even if the vagaries of the implementation make that possible. The reason is vagaries of the implementation, so it may work on one implementation but not another. Currently, whether it (used to) work or not also depended on the contents of the struct being returned. Why should we leave this to vagaries? An rvalue is not an lvalue, period. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167
Eldar Insafutdinov e.insafutdi...@gmail.com changed:
What|Removed |Added
CC||e.insafutdi...@gmail.com
--- Comment #12 from Eldar Insafutdinov e.insafutdi...@gmail.com 2010-01-29
15:00:25 PST ---
(In reply to comment #10)
I'm going to mark this as invalid, as function return values should be
rvalues,
and rvalues cannot be references, even if the vagaries of the implementation
make that possible.
The reason is vagaries of the implementation, so it may work on one
implementation but not another. Currently, whether it (used to) work or not
also depended on the contents of the struct being returned.
This test case fails for me with the latest dmd:
struct X {
}
X i() {
return X.init;
}
void foo(const ref X x) {
}
void foo() {
foo(i()); //line 12
}
This bug is not invalid.
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[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167 --- Comment #13 from Walter Bright bugzi...@digitalmars.com 2010-01-29 15:50:10 PST --- It is invalid code because you are taking a reference to the return value of a function. Functions return, by definition, rvalues. You cannot take a reference to an rvalue. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167
Steven Schveighoffer schvei...@yahoo.com changed:
What|Removed |Added
CC||schvei...@yahoo.com
--- Comment #14 from Steven Schveighoffer schvei...@yahoo.com 2010-01-29
19:24:11 PST ---
(In reply to comment #13)
It is invalid code because you are taking a reference to the return value of a
function. Functions return, by definition, rvalues. You cannot take a
reference
to an rvalue.
This breaks custom types. Who are you as the compiler to assume my type is an
rvalue?
e.g.
class MyClass
{
struct myForwardRange {...}
@property myForwardRange all() {...}
}
void copy(R1, R2)(ref R1 inputrange, ref R2 outputrange)
{
...
}
void foo(MyClass mc, OutputRange r)
{
copy(mc.all, r);
}
Another case:
struct LargeStruct
{
int[100] bigarray;
void print(streamtype s) {s.print(bigarray);}
}
class X
{
LargeStruct createalargestruct() {...}
}
void foo(X x)
{
x.createalargestruct().print(stdout);
}
Also, if you can't call properties on a struct, which essentially needs a
reference to the struct, then you can't get any properties from a returned
struct.
This rule is way too limiting. at the very least, const rvalue references need
to be allowed for any reasonable value types that are not just POD to be
created.
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[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167 Don clugd...@yahoo.com.au changed: What|Removed |Added CC||2kor...@gmail.com --- Comment #9 from Don clugd...@yahoo.com.au 2009-10-15 05:27:05 PDT --- *** Issue 2852 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: ---
[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167 Don clugd...@yahoo.com.au changed: What|Removed |Added CC||clugd...@yahoo.com.au --- Comment #4 from Don clugd...@yahoo.com.au 2009-08-06 00:08:01 PDT --- (In reply to comment #3) I'm fairly sure this was by design (bug 2621) in D 2.026, but I don't think it was expected to seep through to D1. It might be related to the fix for bug #2323 ? My patch for that bug was rejected, so I don't know what changes were made. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167 Bill Baxter wbax...@gmail.com changed: What|Removed |Added CC||wbax...@gmail.com --- Comment #5 from Bill Baxter wbax...@gmail.com 2009-08-06 06:40:55 PDT --- (In reply to comment #3) I'm fairly sure this was by design (bug 2621) in D 2.026, but I don't think it was expected to seep through to D1. I hope you're right. In D2 you can have the ref argument be const (which I hope eliminates the error), but in D1 you have no such option. So you often have to resort to making arguments 'ref' for efficiency even when the function doesn't modify the argument. Also the error message could be a little clearer. Something like Can't pass a temporary to a function taking a ref argument would be a lot clearer I think. Passing something to a function taking a ref does not necessarily imply assigning to that ref argument in D1, for the reason stated above. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167 --- Comment #6 from Don clugd...@yahoo.com.au 2009-08-06 12:24:14 PDT --- This change is clearly caused by the addition of the new function Expression *CallExp::modifiableLvalue(Scope *sc, Expression *e) in expression.c. Comment it out to restore the old behaviour. It doesn't seem to be necessary for any bug fixes -- eg, removing it doesn't reactivate bug 2323. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 3167] Passing result of a function call as ref argument no longer works
http://d.puremagic.com/issues/show_bug.cgi?id=3167 Christian Kamm kamm-removet...@incasoftware.de changed: What|Removed |Added CC||kamm-removet...@incasoftwar ||e.de --- Comment #3 from Christian Kamm kamm-removet...@incasoftware.de 2009-07-12 12:35:26 PDT --- I'm fairly sure this was by design (bug 2621) in D 2.026, but I don't think it was expected to seep through to D1. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
