[Issue 9325] New: writeln of const class instance

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=9325

           Summary: writeln of const class instance
           Product: D
           Version: D2
          Platform: x86
        OS/Version: Windows
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: Phobos
        AssignedTo: nobody at puremagic.com
        ReportedBy: bearophile_hugs at eml.cc


--- Comment #0 from bearophile_hugs at eml.cc 2013-01-16 01:45:53 PST ---
This program:


import std.stdio: writeln;
class Foo { int x = 5; }
void main() {
    auto f = new Foo;
    writeln(f);
}


Prints (dmd 2.062alpha):

test1.Foo



While this:


import std.stdio: writeln;
class Foo { int x = 5; }
void main() {
    const f = new Foo;
    writeln(f);
}



Gives:

...\dmd2\src\phobos\std\format.d(2435): Error: template instance
formatObject!(LockingTextWriter, const(Foo), char)
formatObject!(LockingTextWriter, const(Foo), char) does not match template
declaration formatObject(Writer, T, Char)(ref Writer w, ref T val, ref
FormatSpec!(Char) f) if (hasToString!(T, Char))
...\dmd2\src\phobos\std\format.d(2435): Error: function expected before (), not
formatObject!(LockingTextWriter, const(Foo), char) of type void
...\dmd2\src\phobos\std\format.d(2863): Error: template instance
std.format.formatValue!(LockingTextWriter, const(Foo), char) error
instantiating
...\dmd2\src\phobos\std\format.d(415):        instantiated from here:
formatGeneric!(LockingTextWriter, const(Foo), char)
...\dmd2\src\phobos\std\stdio.d(714):        instantiated from here:
formattedWrite!(LockingTextWriter, char, const(Foo))
...\dmd2\src\phobos\std\stdio.d(1620):        instantiated from here:
write!(const(Foo),char)
test2.d(5):        instantiated from here: writeln!(const(Foo))
...\dmd2\src\phobos\std\format.d(415): Error: template instance
std.format.formatGeneric!(LockingTextWriter, const(Foo), char) error
instantiating
...\dmd2\src\phobos\std\stdio.d(714):        instantiated from here:
formattedWrite!(LockingTextWriter, char, const(Foo))
...\dmd2\src\phobos\std\stdio.d(1620):        instantiated from here:
write!(const(Foo),char)
test2.d(5):        instantiated from here: writeln!(const(Foo))
...\dmd2\src\phobos\std\stdio.d(714): Error: template instance
std.format.formattedWrite!(LockingTextWriter, char, const(Foo)) error
instantiating
...\dmd2\src\phobos\std\stdio.d(1620):        instantiated from here:
write!(const(Foo),char)
test2.d(5):        instantiated from here: writeln!(const(Foo))
...\dmd2\src\phobos\std\stdio.d(1620): Error: template instance
std.stdio.File.write!(const(Foo),char) error instantiating
test2.d(5):        instantiated from here: writeln!(const(Foo))
test2.d(5): Error: template instance std.stdio.writeln!(const(Foo)) error
instantiating

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