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digitalmars.D.bugs - Possible lvalue vs rvalue bug with struct?

reply Kevin Bealer <Kevin_member pathlink.com> writes:
I get the error:

ut_wrapper.d(38): ranges.opIndex(i) is not an lvalue

A. Line 38 is marked.
B. If ranges is made into a "class" the issue disappears.
C. If the expression is seperated, the issue disappears.
D. But changing the name "length" (in range.length) doesn't affect it.

:
: import std.stdio;
: 
: //class range {  // B
: struct range {
:     size_t begin;
:     size_t end;
:     
:     int length() // D
:     {
:         return end-begin;
:     }
: }
: 
: class Container {
:     range opIndex(size_t i)
:     in
:     {
:         assert(i < data.length);
:     }
:     body
:     {
:         return data[i];
:     }
:     
: private:
:     range[] data;
: }
: 
: int main()
: {
:     Container ranges;
:     
:     size_t i = 0;
:     
:     //range r = ranges[i];   // C
:     //if (r.length == 1) {   // C
:     if (ranges[i].length == 1) {  // A. LINE 38
:         writefln("range==1");
:     }
:     
:     return 0;
: }
: 

Kevin
Apr 24 2005
next sibling parent reply Derek Parnell <derek psych.ward> writes:
On Sun, 24 Apr 2005 23:30:56 +0000 (UTC), Kevin Bealer wrote:


 I get the error:
 
 ut_wrapper.d(38): ranges.opIndex(i) is not an lvalue
 


[snip]

I cannot reproduce that error with the code you gave us. 

Here is your code with a couple of changes to get it to run okay. The
changes are marked with //DJP but they shouldn't have influenced the
reported error.

// ---------------------------
import std.stdio;
 
struct range {
     size_t begin;
     size_t end;
     
     int length() // D
     {
         return end-begin;
     }
 }
 
class Container {
     range opIndex(size_t i)
     in
     {
         assert(i < data.length);
     }
     body
     {
         return data[i];
     }
     
     // DJP To get at least one range to test.
     void AddRange(size_t b, size_t e)
     {
         data.length = data.length + 1;
         data[$-1].begin = b;    
         data[$-1].end = e;
    }     
    
 private:
     range[] data;
 }
 
 int main()
 {
     Container ranges = new Container; //DJP     
     ranges.AddRange(2,6); //DJP

     size_t i = 0;
     
     if (ranges[i].length == 1) {
         writefln("range==1");
     }
     
     return 0;
 }
 
// ---------------------------


-- 
Derek Parnell
Melbourne, Australia
25/04/2005 9:57:21 AM
Apr 24 2005
parent Kevin Bealer <Kevin_member pathlink.com> writes:
In article <fcl7wqonidem$.wcyai42foe58.dlg 40tude.net>, Derek Parnell says...

On Sun, 24 Apr 2005 23:30:56 +0000 (UTC), Kevin Bealer wrote:


 I get the error:
 
 ut_wrapper.d(38): ranges.opIndex(i) is not an lvalue
 


[snip]

I cannot reproduce that error with the code you gave us. 

Here is your code with a couple of changes to get it to run okay. The
changes are marked with //DJP but they shouldn't have influenced the
reported error.


(snip)

I actually hadn't thought to run the program (I'm working with a larger project
and this is a boil-down of an error I saw).

The error I got was at compile time.  I checked the compile options, and the
error goes away if "-inline" is not specified.

This is with version 0.121.

Kevin
Apr 24 2005
prev sibling parent Thomas Kuehne <thomas-dloop kuehne.thisisspam.cn> writes:
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Hash: SHA1

Kevin Bealer schrieb am Sun, 24 Apr 2005 23:30:56 +0000 (UTC):

 I get the error:

 ut_wrapper.d(38): ranges.opIndex(i) is not an lvalue

 A. Line 38 is marked.
 B. If ranges is made into a "class" the issue disappears.
 C. If the expression is seperated, the issue disappears.
 D. But changing the name "length" (in range.length) doesn't affect it.

:
: import std.stdio;
: 
: //class range {  // B
: struct range {
:     size_t begin;
:     size_t end;
:     
:     int length() // D
:     {
:         return end-begin;
:     }
: }
: 
: class Container {
:     range opIndex(size_t i)
:     in
:     {
:         assert(i < data.length);
:     }
:     body
:     {
:         return data[i];
:     }
:     
: private:
:     range[] data;
: }
: 
: int main()
: {
:     Container ranges;
:     
:     size_t i = 0;
:     
:     //range r = ranges[i];   // C
:     //if (r.length == 1) {   // C
:     if (ranges[i].length == 1) {  // A. LINE 38
:         writefln("range==1");
:     }
:     
:     return 0;
: }
: 

 Kevin


Added to DStress as
http://dstress.kuehne.cn/run/opIndex_01.d
http://dstress.kuehne.cn/run/opIndex_02.d
http://dstress.kuehne.cn/run/opIndex_03.d
http://dstress.kuehne.cn/run/opIndex_04.d

Thomas


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Apr 24 2005