digitalmars.D.bugs - A strange bug with using functions as args
- BCS (27/27) Sep 15 2005 I have run into what I think is a bug.
- Hasan Aljudy (28/67) Sep 15 2005 This doesn't help much, I tried the following (see below) and it worked
- BCS (2/69) Sep 15 2005
-
Stewart Gordon
(21/22)
Sep 16 2005
- BCS (47/65) Sep 16 2005 I posted that code because it gives general idea of what the bug is in t...
I have run into what I think is a bug.
The code (sort of)
class A
{
int foo(){...} // always returns the same number (in this case)
int bar(int i) {...} // returns a function of only i
int runA()
{
return bar(foo());
}
int runB()
{
int i = foo();
return bar(i);
}
}
void main()
{
A a = new A;
writef(a.runA(), \n);
writef(a.runB(), \n);
}
(This code isn't the code with the bug, that code is 15k+ lines long.)
The bug: A.runA and A.runB return different numbers.
In my actual code storing the function to a temp variable and using that changed
the output.
Any ideas??
Sep 15 2005
This doesn't help much, I tried the following (see below) and it worked
fine.
Maybe it's what the function bar is doing in your code ..
Could you try to provide a more specific test case?
This works fine:
----------------------------------------
import std.stdio;
class A
{
int foo(){ return 5; }
int bar(int i) { return i + 1; }
int runA()
{
return bar(foo());
}
int runB()
{
int i = foo();
return bar(i);
}
}
void main()
{
A a = new A;
writef(a.runA(), \n);
writef(a.runB(), \n);
}
BCS wrote:
I have run into what I think is a bug.
The code (sort of)
class A
{
int foo(){...} // always returns the same number (in this case)
int bar(int i) {...} // returns a function of only i
int runA()
{
return bar(foo());
}
int runB()
{
int i = foo();
return bar(i);
}
}
void main()
{
A a = new A;
writef(a.runA(), \n);
writef(a.runB(), \n);
}
(This code isn't the code with the bug, that code is 15k+ lines long.)
The bug: A.runA and A.runB return different numbers.
In my actual code storing the function to a temp variable and using that
changed
the output.
Any ideas??
Sep 15 2005
BCS <BCS_member pathlink.com>
I'll try to strip it down but don't hold you'r breath. It's quite involved code.
In article <dgci00$1u4p$1 digitaldaemon.com>, Hasan Aljudy says...
This doesn't help much, I tried the following (see below) and it worked
fine.
Maybe it's what the function bar is doing in your code ..
Could you try to provide a more specific test case?
This works fine:
----------------------------------------
import std.stdio;
class A
{
int foo(){ return 5; }
int bar(int i) { return i + 1; }
int runA()
{
return bar(foo());
}
int runB()
{
int i = foo();
return bar(i);
}
}
void main()
{
A a = new A;
writef(a.runA(), \n);
writef(a.runB(), \n);
}
BCS wrote:
I have run into what I think is a bug.
The code (sort of)
class A
{
int foo(){...} // always returns the same number (in this case)
int bar(int i) {...} // returns a function of only i
int runA()
{
return bar(foo());
}
int runB()
{
int i = foo();
return bar(i);
}
}
void main()
{
A a = new A;
writef(a.runA(), \n);
writef(a.runB(), \n);
}
(This code isn't the code with the bug, that code is 15k+ lines long.)
The bug: A.runA and A.runB return different numbers.
In my actual code storing the function to a temp variable and using that
changed
the output.
Any ideas??
Sep 15 2005
BCS wrote: <snip>(This code isn't the code with the bug, that code is 15k+ lines long.)<snip> If this code doesn't have the bug, then why did you post it? A good idea is to try first to reproduce the bug by writing a short program from scratch. Then, if that fails, then try trimming your program down. This might help you: http://www.physci.org/codes/sscce.jsp (It's actually aimed at being a technique for isolating bugs in your programs, but many of the points are also applicable to writing compiler bug testcases.) Stewart. -- -----BEGIN GEEK CODE BLOCK----- Version: 3.1 GCS/M d- s:- C++ a->--- UB P+ L E W++ N+++ o K- w++ O? M V? PS- PE- Y? PGP- t- 5? X? R b DI? D G e++>++++ h-- r-- !y ------END GEEK CODE BLOCK------ My e-mail is valid but not my primary mailbox. Please keep replies on the 'group where everyone may benefit.
Sep 16 2005
I posted that code because it gives general idea of what the bug is in the hope
that someone would recognize it a similar to something they had encountered. I
plan to try to strip down the real code but I expect it will not be vary
fruitful. My best guess is that it is a compiler bug (or something that will
make me feel vary stupid) or some such thing.
Below is a better approximation of the real code. (This actually does a simpler
case of what the real thing does.) In the real thing, on line 6, storing the
value of the 2nt argument to a temp variable before the call changes how things
run.
This code also doesn’t have the bug. (Sorry)
#import std.math;
#import std.stdio;
#class Taylor
#{
# void regen(real time) {n = newInert(n.P(time), n.V(time));} //line 6
# real P(real time) { return n.P(time); }
# static Newton newInert(real p, real v)
# { return new Newton(p, v, Acc(p), Jrk(p)); }
# static real Acc(real p) { return -p; }
# static real Jrk(real p) { return -sqrt(1 - p*p); }
# Newton n;
#}
#class Newton
#{
# this(real nP, real nV, real nA, real nJ)
# {
# p=nP; v=nV; a=nA; j=nJ;
# writef("%g %g %g %g \n", p, v, a, j);
# }
# real P(real time) { return p + v*time + a*(time*time/2) +
j*(time*time*time/6); }
# real V(real time) { return v + a*time + j*(time*time/2); }
# real p;
# real v;
# real a;
# real j;
#}
#void main()
#{
# Taylor t = new Taylor;
# t.n = Taylor.newInert(.999, 0);
# for(int i=0; i< 26; i++)
# t.regen(.1);
#}
One candidate for a cause is that the compiler Is inlineing the calls at line 6
and time is getting changed some where in the first call.
In article <dgf13m$1a2m$1 digitaldaemon.com>, Stewart Gordon says...
If this code doesn't have the bug, then why did you post it?
A good idea is to try first to reproduce the bug by writing a short
program from scratch. Then, if that fails, then try trimming your
program down.
This might help you:
http://www.physci.org/codes/sscce.jsp
(It's actually aimed at being a technique for isolating bugs in your
programs, but many of the points are also applicable to writing compiler
bug testcases.)
Stewart.
--
-----BEGIN GEEK CODE BLOCK-----
Version: 3.1
GCS/M d- s:- C++ a->--- UB P+ L E W++ N+++ o K- w++ O? M V? PS-
PE- Y? PGP- t- 5? X? R b DI? D G e++>++++ h-- r-- !y
------END GEEK CODE BLOCK------
My e-mail is valid but not my primary mailbox. Please keep replies on
the 'group where everyone may benefit.
Sep 16 2005