www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.learn - new error message in 2.066, type bool (const)

reply "Paul D Anderson" <claude.rains msn.com> writes:
Re-compiling existing code with version 2.066 generates a lot of 
errors complaining about implicit conversion to const. Typical is 
this call (inside a struct with properties 1 & 2):

	z.sign = x.sign ^ y.sign;

Error: None of the overloads of 'sign' are callable using 
argument types bool (const), candidates are:

1)	 property
	 safe
	bool sign() const
	{
		return signed;
	}

2)	 property
	 safe
	bool sign(in bool value)
	{
		signed = value;
		return signed;
	}

What changed? It ran okay with early beta versions, but not with 
the release.

Paul
Aug 20 2014
next sibling parent "monarch_dodra" <monarchdodra gmail.com> writes:
On Wednesday, 20 August 2014 at 20:46:20 UTC, Paul D Anderson 
wrote:

 Re-compiling existing code with version 2.066 generates a lot 
 of errors complaining about implicit conversion to const. 
 Typical is this call (inside a struct with properties 1 & 2):

 	z.sign = x.sign ^ y.sign;

 Error: None of the overloads of 'sign' are callable using 
 argument types bool (const), candidates are:

 1)	 property
 	 safe
 	bool sign() const
 	{
 		return signed;
 	}

 2)	 property
 	 safe
 	bool sign(in bool value)
 	{
 		signed = value;
 		return signed;
 	}

 What changed? It ran okay with early beta versions, but not 
 with the release.

 Paul


Could you provide a short, but complete program that reproduces 
the issue? With this:

//----
struct S
{
     bool signed;
      property
      safe
     bool sign() const
     {
         return signed;
     }

      property
      safe
     bool sign(in bool value)
     {
         signed = value;
         return signed;
     }
}

void main(string[] args)
{
     S s;
     s.sign = s.sign ^ s.sign;
}
//----

It works for me with both 2.065.0 and 2.066.0.

What is the type of "signed" ? Is it something other than bool, 
by any chance?
Aug 20 2014
prev sibling next sibling parent reply "Paul D Anderson" <claude.rains msn.com> writes:
 What changed? It ran okay with early beta versions, but not 
 with the release.

 Paul


It compiles in beta-5 but not beta-6. Is the list of changes in 
the beta testing wiki complete? None seem pertinent.

monarch_dodra: Thanks for checking. I was trying to avoid tearing 
everything down. I was hoping someone would recognize the error. 
Looks like I'll have to chase it down.

Paul
Aug 20 2014
parent "Brad Anderson" <eco gnuk.net> writes:
On Thursday, 21 August 2014 at 03:02:53 UTC, Paul D Anderson 
wrote:

 What changed? It ran okay with early beta versions, but not 
 with the release.

 Paul


 It compiles in beta-5 but not beta-6. Is the list of changes in 
 the beta testing wiki complete? None seem pertinent.

 monarch_dodra: Thanks for checking. I was trying to avoid 
 tearing everything down. I was hoping someone would recognize 
 the error. Looks like I'll have to chase it down.

 Paul


https://github.com/CyberShadow/digger should be able to help find 
the exact commit. A reduced example would help us figure out what 
is going on though.
Aug 21 2014
prev sibling parent reply "Paul D Anderson" <claude.rains msn.com> writes:
On Wednesday, 20 August 2014 at 20:46:20 UTC, Paul D Anderson 
wrote:

 Re-compiling existing code with version 2.066 generates a lot 
 of errors complaining about implicit conversion to const. 
 Typical is this call (inside a struct with properties 1 & 2):

 	z.sign = x.sign ^ y.sign;

 Error: None of the overloads of 'sign' are callable using 
 argument types bool (const), candidates are:

 1)	 property
 	 safe
 	bool sign() const
 	{
 		return signed;
 	}

 2)	 property
 	 safe
 	bool sign(in bool value)
 	{
 		signed = value;
 		return signed;
 	}

 What changed? It ran okay with early beta versions, but not 
 with the release.

 Paul


The problem (not obvious from the above) is that a templated type 
is bringing its qualifiers into the template.

Here is a small example:

T add(T)(in T x, in T y)
{
	T z;
	z = x + y;
	return z;
}

void main()
{
	const double a = 1.0;
	const double b = 2.0;
	double c;
	c = add(a,b);
}

Error: Cannot modify immutable expression z

---

Since a and b are const double the deduced template type is also 
const double. Then when z is declared as type T it is also const.

This compiled and ran in beta 5 but not in beta 6.

If I modify the above so that declaration and assignment are 
performed at the same time:

	T z = x + y;

This compiles and assigns the (const double) value 3.0 to z. 
After the function call c contains the double value 3.0, but it 
is no longer const.

The error can be avoided by declaring z to be of type Unqual!T in 
most cases.

I don't know if this is expected behavior that just wasn't 
enforced before, or if this is something new. Either way I don't 
like it. And I'm a little surprised I'm the only one affected by 
this. I'll keep digging.

Paul
Aug 21 2014
parent "Paul D Anderson" <claude.rains msn.com> writes:
On Friday, 22 August 2014 at 01:25:05 UTC, Paul D Anderson wrote:

 On Wednesday, 20 August 2014 at 20:46:20 UTC, Paul D Anderson I 
 don't know if this is expected behavior that just wasn't 
 enforced before, or if this is something new. Either way I 
 don't like it. And I'm a little surprised I'm the only one 
 affected by this. I'll keep digging.

 Paul


https://issues.dlang.org/show_bug.cgi?id=13351
Aug 21 2014