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digitalmars.D.bugs - Compiler does not always honor typedef contract

reply Roberto Mariottini <Roberto_member pathlink.com> writes:
Hi,
Tried with DMD v0.141 on Windows XP:

typedef int apples;
typedef int pears;

int main(char[][] args)
{
int i = 13;
apples a = 13; // OK (?)
apples a2 = i; // cannot implicitly convert expression (i) of type int to apples
pears p = 13;  // OK (?)
pears p2 = i;  // cannot implicitly convert expression (i) of type int to pears

a = a + a; // OK
a = a + 1; // OK (?)
a = a + i; // OK (?)
a = a + p; // OK (???)
a = 1 + a; // cannot implicitly convert expression (1 + a) of type int to apples
a = i + a; // cannot implicitly convert expression (i + a) of type int to apples
a = p + a; // cannot implicitly convert expression (p + a) of type pears to
apples
a = cast(apples) 1 + a; // OK
a = cast(apples) i + a; // OK
a = cast(apples) p + a; // OK

return 0;
}
Dec 05 2005
parent reply "Walter Bright" <newshound digitalmars.com> writes:
"Roberto Mariottini" <Roberto_member pathlink.com> wrote in message
news:dn1gtg$145u$1 digitaldaemon.com...

 Hi,
 Tried with DMD v0.141 on Windows XP:

 typedef int apples;
 typedef int pears;

 int main(char[][] args)
 {
 int i = 13;
 apples a = 13; // OK (?)


Yes. Using typedefs would be useless if this didn't work.


 apples a2 = i; // cannot implicitly convert expression (i) of type int to


apples

Yes. Otherwise there is no point to typedef's. <g>


 pears p = 13;  // OK (?)
 pears p2 = i;  // cannot implicitly convert expression (i) of type int to


pears

 a = a + a; // OK
 a = a + 1; // OK (?)


Yes.


 a = a + i; // OK (?)


This should be allowed.


 a = a + p; // OK (???)


This should not be allowed.


 a = 1 + a; // cannot implicitly convert expression (1 + a) of type int to


apples

This should be allowed.


 a = i + a; // cannot implicitly convert expression (i + a) of type int to


apples

This should be allowed.


 a = p + a; // cannot implicitly convert expression (p + a) of type pears


to

 apples


This should not be allowed.


 a = cast(apples) 1 + a; // OK
 a = cast(apples) i + a; // OK
 a = cast(apples) p + a; // OK

 return 0;
 }
Dec 05 2005
next sibling parent Roberto Mariottini <Roberto_member pathlink.com> writes:
In article <dn203h$1q0n$1 digitaldaemon.com>, Walter Bright says...


[...]

 typedef int apples;
 typedef int pears;

 int main(char[][] args)
 {
 int i = 13;
 apples a = 13; // OK (?)


Yes. Using typedefs would be useless if this didn't work.


I understand, even if I disagree. I am for strong typing, for this case I prefer
a constructor approach, like:

apples a = apples(13);

And what about function parameter passing?

void f (apples x) { ... }
..
f(13); // is this allowed?

In my opinion this should be an error.


 apples a2 = i; // cannot implicitly convert expression (i) of type int to


apples

Yes. Otherwise there is no point to typedef's. <g>


Indeed.

[...]

 a = a + 1; // OK (?)


Yes.


I disagree, see above.


 a = a + i; // OK (?)


This should be allowed.


How this is different from:

apples a2 = i;

For consistency this should be an error as well.


 a = a + p; // OK (???)


This should not be allowed.


Obviously.

Ciao



 Dec 07 2005



prev sibling  parent  Thomas Kuehne <thomas-dloop kuehne.cn>  writes:


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Walter Bright schrieb am 2005-12-05:

 "Roberto Mariottini" <Roberto_member pathlink.com> wrote in message
 news:dn1gtg$145u$1 digitaldaemon.com...

 Hi,
 Tried with DMD v0.141 on Windows XP:

 typedef int apples;
 typedef int pears;

 int main(char[][] args)
 {
 int i = 13;
 apples a = 13; // OK (?)




[snip]


 a = i + a; // cannot implicitly convert expression (i + a) of type int to


 apples

 This should be allowed.


[snip]

Where is this documented?



Added to DStress as
http://dstress.kuehne.cn/nocompile/t/typedef_09_A.d
http://dstress.kuehne.cn/nocompile/t/typedef_09_B.d
http://dstress.kuehne.cn/nocompile/t/typedef_09_C.d
http://dstress.kuehne.cn/run/t/typedef_09_D.d
http://dstress.kuehne.cn/run/t/typedef_09_E.d
http://dstress.kuehne.cn/run/t/typedef_09_F.d

Thomas


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 Dec 18 2005