[Issue 3605] Compiler accepts invalid variable declaration, which does not link
https://issues.dlang.org/show_bug.cgi?id=3605 Andrei Alexandrescu changed: What|Removed |Added Version|2.036 |D2 --
[Issue 3605] Compiler accepts invalid variable declaration, which does not link
http://d.puremagic.com/issues/show_bug.cgi?id=3605 Lars T. Kyllingstad changed: What|Removed |Added Status|NEW |RESOLVED Resolution||INVALID --- Comment #5 from Lars T. Kyllingstad 2009-12-11 05:54:05 PST --- That's a good point. I'd forgotten about .di files. But still, I think it doesn't make sense to allow empty *nested* function declarations. Nested functions are only visible inside the enclosing function scope, and as such wouldn't be included in a .di file. Anyway, that's another discussion. I'm marking this as invalid. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 3605] Compiler accepts invalid variable declaration, which does not link
http://d.puremagic.com/issues/show_bug.cgi?id=3605 --- Comment #4 from Michal Minich 2009-12-11 04:15:06 PST --- Thank you for explanation Lars, It did not occurred to me that "int i();" can be function declaration. Maybe if such declaration required extern(D) attribute, it would be more clear what's going on. I cannot imagine what is this feature intended to do… Maybe it has some use in connection with .di files… -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
[Issue 3605] Compiler accepts invalid variable declaration, which does not link
http://d.puremagic.com/issues/show_bug.cgi?id=3605
--- Comment #3 from Lars T. Kyllingstad 2009-12-11
03:37:30 PST ---
I will would like to say though, that it shouldn't be possible to declare
functions like this in D. With the module system, I can't see any practical way
of defining a function in a separate .d file, as its name will be mangled with
the module name. Here's an example:
x.d:
import std.stdio;
void print(int i) { writeln(i); }
y.d:
void print(int);
void main() { print(123); }
$ dmd -c x.d
$ dmd y.d x.o
y.o: In function `_Dmain':
y.d:(.text._Dmain+0x9): undefined reference to `_D1y5printFiZv'
collect2: ld returned 1 exit status
--- errorlevel 1
The declaration in y.d is mangled as _D1y5printFiZv, which means y.print(int),
while the object file will contain _D1x5printFiZv, or x.print(int).
-Lars
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[Issue 3605] Compiler accepts invalid variable declaration, which does not link
http://d.puremagic.com/issues/show_bug.cgi?id=3605
Lars T. Kyllingstad changed:
What|Removed |Added
CC||bugzi...@kyllingen.net
--- Comment #2 from Lars T. Kyllingstad 2009-12-11
03:20:09 PST ---
This is expected and well-defined behaviour. I'll explain:
(In reply to comment #0)
> 1. struct, class and union type: Error 42: Symbol Undefined
> _D4main4mainFZv1sMFZS4main2S2
>
> struct S { int x; }
> void main ()
> {
Here you declare a function s() which returns an S, without the function body.
The linker will expect to find it in some library or object file.
>S s(); // braces should not be allowed.
>s.x = 1; // comment this line and example compiles and runs
> }
>
>
> 2. int type: Error 42: Symbol Undefined _D4main4mainFZv1iMFZi
>
> void main ()
> {
> int i(); // braces should not be allowed.
Same here, the compiler assumes that the function i() will be linked in later,
and therefore accepts it. The next line works because of the property syntax
for calling functions. Writing i.max is equivalent to writing i().max. The
property max is available for all ints.
> int a = i.max; // surprisingly this and next line works.
> writeln (a);
The next line also works because of the property syntax. Writing i=1 is
equivalent to writing i(1).
> //i = 1; // uncomment this to cause error
> //writeln (i); // or this
> }
>
>
> 2b. this example works correctly – compiler gives some error message, even if
> not so appropriate.
> Error: function main.main.i () is not callable using argument types (int)
> Error: expected 0 arguments, not 1 for non-variadic function type int()
This is because the compiler interprets i=1 as i(1), which doesn't work since
you have declared i() without any parameters.
> void main ()
> {
> int i();
> i = 1;
> }
Note that this confusing stuff will most likely disappear in the near future,
as property functions will have to be annotated with the @property attribute.
void foo(int i);
foo = 123; // won't work, must write foo(123)
@property void bar(int i);
bar = 123; // that's more like it
You can read about it in the spec, but note again that @property isn't yet
REQUIRED for this to work:
http://www.digitalmars.com/d/2.0/function.html#property-functions
-Lars
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[Issue 3605] Compiler accepts invalid variable declaration, which does not link
http://d.puremagic.com/issues/show_bug.cgi?id=3605 --- Comment #1 from Michal Minich 2009-12-11 02:59:28 PST --- Correction: in example 2 "i = 1;" will not cause error, only "writeln (i);" causes it. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email --- You are receiving this mail because: ---
