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digitalmars.D.learn - dmd 2.093.1: duplicate method definitions ignored altogether

reply kdevel <kdevel vogtner.de> writes:
~~~tsnf.d
import std.stdio: writeln;

struct S {
    string s;
    string toString ()
    {
       return __PRETTY_FUNCTION__ ~ `: ` ~ s;
    }

    {
       return __PRETTY_FUNCTION__ ~ `: ` ~ s;
    }

    {
       return __PRETTY_FUNCTION__ ~ `: ` ~ s;
    }
}

void foo (T) (in ref T t) // fancy way of declaring t const
{
    writeln (t);
}

int main ()
{
    S s;
    writeln (s);
    foo (s);
    return 0;
}
~~~

$ dmd tsnf
$ ./tsnf
string tsnf.S.toString():
const(S)("")

expected output: none. The compiler should have rejected the code 

definitions instead. Is this a bug or a bug?
Jan 04
next sibling parent reply Paul Backus <snarwin gmail.com> writes:
On Tuesday, 5 January 2021 at 02:02:39 UTC, kdevel wrote:
 expected output: none. The compiler should have rejected the 

 both definitions instead. Is this a bug or a bug?
If you try to call .toString directly on a const(S), you get the following error: onlineapp.d(27): Error: onlineapp.S.toString called with argument types () const matches both: onlineapp.d(9): onlineapp.S.toString() const and: onlineapp.d(13): onlineapp.S.toString() const The reason it is ignored when using writeln is that writeln uses __traits(compiles) to check whether it can call toString on a const(S). Since the call does not compile, it falls back to the default struct formatting code, which produces the output you saw in your example.
Jan 04
parent kdevel <kdevel vogtner.de> writes:
On Tuesday, 5 January 2021 at 03:36:47 UTC, Paul Backus wrote:
 On Tuesday, 5 January 2021 at 02:02:39 UTC, kdevel wrote:
[...]
 If you try to call .toString directly on a const(S), you get 
 the following error:

 onlineapp.d(27): Error: onlineapp.S.toString called with 
 argument types () const matches both:
 onlineapp.d(9):     onlineapp.S.toString() const
 and:
 onlineapp.d(13):     onlineapp.S.toString() const
Sure, but that's too late. IMHO the compiler should detect duplicate definitions (probably concealing a program error) regardless whether the method is called. There is a difference between calls which match two or more functions and duplicate definitions. Isn't it? Other compilers for other languages complain loud and clear: ```ddcpp.cc template<typename T> struct X { int foo () { return 0; } int foo () { return 0; } }; ``` result from clang++: ddcpp.cc:7:8: error: class member cannot be redeclared int foo () ^ ddcpp.cc:3:8: note: previous declaration is here int foo () ^ ddcpp.cc:7:8: error: redefinition of 'foo' int foo () ^ ddcpp.cc:3:8: note: previous definition is here int foo () ^ 2 errors generated.
Jan 04
prev sibling parent Jacob Carlborg <doob me.com> writes:
On 2021-01-05 03:02, kdevel wrote:

 expected output: none. The compiler should have rejected the code after 

 instead. Is this a bug or a bug?
DMD 2.095.0 now reports an error for this. -- /Jacob Carlborg
Jan 06