Bug 20632 – Format and writeln not usable with non-copyable types

It is probably the evidence of a larger problem, and fixing it is probably limited by fixes to the ABI, but here it goes: ``` import std.stdio; private struct MyStruct { int a; string b; @disable this(this); @disable ref MyStruct opAssign(ref MyStruct other); } void main () { MyStruct s; writeln(s); } ``` This code *should* compile. We should be able to take a value by ref and just format or print it. This is quite important when you have `extern(C++)` types where copy is expensive. Even adding my own `toString` to it: ``` string toString() @safe pure nothrow @nogc { return "WhyNot"; } ``` does not make it compile.

Note that the errors I'm getting right now, without the `toString`, are: ``` /usr/local/opt/dmd/include/dlang/dmd/std/stdio.d(1505): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/format.d(4813): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/format.d(494): Error: template instance std.format.getNthInt!("integer width", MyStruct) error instantiating /usr/local/opt/dmd/include/dlang/dmd/std/stdio.d(1512): instantiated from here: formattedWrite!(LockingTextWriter, char, MyStruct) /usr/local/opt/dmd/include/dlang/dmd/std/stdio.d(3870): instantiated from here: write!(MyStruct, char) foo.d(15): instantiated from here: writeln!(MyStruct) /usr/local/opt/dmd/include/dlang/dmd/std/format.d(494): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/format.d(508): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/format.d(4813): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/format.d(520): Error: template instance std.format.getNthInt!("integer precision", MyStruct) error instantiating /usr/local/opt/dmd/include/dlang/dmd/std/stdio.d(1512): instantiated from here: formattedWrite!(LockingTextWriter, char, MyStruct) /usr/local/opt/dmd/include/dlang/dmd/std/stdio.d(3870): instantiated from here: write!(MyStruct, char) foo.d(15): instantiated from here: writeln!(MyStruct) /usr/local/opt/dmd/include/dlang/dmd/std/format.d(520): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/format.d(531): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/format.d(4813): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/format.d(540): Error: template instance std.format.getNthInt!("separator digit width", MyStruct) error instantiating /usr/local/opt/dmd/include/dlang/dmd/std/stdio.d(1512): instantiated from here: formattedWrite!(LockingTextWriter, char, MyStruct) /usr/local/opt/dmd/include/dlang/dmd/std/stdio.d(3870): instantiated from here: write!(MyStruct, char) foo.d(15): instantiated from here: writeln!(MyStruct) /usr/local/opt/dmd/include/dlang/dmd/std/format.d(540): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/format.d(548): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/stdio.d(1512): Error: struct foo.MyStruct is not copyable because it is annotated with @disable /usr/local/opt/dmd/include/dlang/dmd/std/stdio.d(3870): Error: struct foo.MyStruct is not copyable because it is annotated with @disable foo.d(15): Error: struct foo.MyStruct is not copyable because it is annotated with @disable ```

*** This issue has been marked as a duplicate of issue 9489 ***