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digitalmars.D.ide - wierdness in debugger

reply Enigma <Enigma dot.com> writes:
When debugging a foreach loop that works on an enum constant, the 
debugger has different behavior if the loop uses brackets or not

The following should demonstrate it:

import std.meta, std.algorithm, std.stdio;
void main()
{
	enum X = AliasSeq!(1,2,3,4,5,3,2,1);
	int y = 0;	
	foreach(x; X)
	   y = max(x, y);
	
	writeln(y);
	
	y = 0;
	foreach(x; X)
	{
	   y = max(x, y);
	}
	
	
	writeln(y);	
}

a BP on the writeln lines will have the debugger skip to the 
writeln when stepping in the first case and not the second.

It's as if the debugger thinks that the statement after the first 
max is part of the for each block or something weird like that. 
Was confusing at first and thought it was a bug because I was 
getting the wrong value for y. When, in fact, the BP on the 
writeln simply did not execute the foreach loop completely like 
it would in the second case, even though it should.
Mar 30
next sibling parent Basile B. <b2.temp gmx.com> writes:
On Thursday, 30 March 2017 at 17:28:44 UTC, Enigma wrote:
 When debugging a foreach loop that works on an enum constant, 
 the debugger has different behavior if the loop uses brackets 
 or not
Which debugger are you talking about GDB, Mago, LLDB ? linux or windows ? which IDE do you use ?
 [...]

 a BP on the writeln lines will have the debugger skip to the 
 writeln when stepping in the first case and not the second.
Can you be more clear ? Let's say i want to reproduce the issue, i put BP on the two writeln, i launch a GDB session, GDB breaks on the first writeln and then ?
 It's as if the debugger thinks that the statement after the 
 first max is part of the for each block or something weird like 
 that. Was confusing at first and thought it was a bug because I 
 was getting the wrong value for y. When, in fact, the BP on the 
 writeln simply did not execute the foreach loop completely like 
 it would in the second case, even though it should.
Mar 31
prev sibling parent Rainer Schuetze <r.sagitario gmx.de> writes:
On 30.03.2017 19:28, Enigma wrote:
 When debugging a foreach loop that works on an enum constant, the
 debugger has different behavior if the loop uses brackets or not

 The following should demonstrate it:

 import std.meta, std.algorithm, std.stdio;
 void main()
 {
     enum X = AliasSeq!(1,2,3,4,5,3,2,1);
     int y = 0;
     foreach(x; X)
        y = max(x, y);

     writeln(y);

     y = 0;
     foreach(x; X)
     {
        y = max(x, y);
     }


     writeln(y);
 }

 a BP on the writeln lines will have the debugger skip to the writeln
 when stepping in the first case and not the second.

 It's as if the debugger thinks that the statement after the first max is
 part of the for each block or something weird like that. Was confusing
 at first and thought it was a bug because I was getting the wrong value
 for y. When, in fact, the BP on the writeln simply did not execute the
 foreach loop completely like it would in the second case, even though it
 should.
There is usually a jump instruction at the end of the for/foreach loop to return to the beginning of the loop. In the first loop this instruction does not have a respective token (with attached line info) that matches well in all cases: - if you choose the "foreach" token, it can be very confusing as the jump instruction can also be the return address of the max() call and shown in the call stack. - if you choose the next token "writeln" you get the confusion when executing the loop as you describe. So it's a trade-off. Debugging C++ has the same issue and also sometimes seems to execute the statement after the loop.
Apr 01