[Issue 16312] "Error: Overlapping fields" caused by use of deprecated features in referred to fields

Jul 22, 2016

Marco Leise

Jul 22, 2016

Mathias Lang

Jul 23, 2016

Jul 23, 2016

Jul 05, 2017

Dec 17, 2022

July 22, 2016

[Issue 16312] "Error: Overlapping fields" caused by use of deprecated features in referred to fields

Posted by Mathias Lang

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Mathias Lang

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https://issues.dlang.org/show_bug.cgi?id=16312

Mathias Lang <mathias.lang@sociomantic.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mathias.lang@sociomantic.co
                   |                            |m

--- Comment #1 from Mathias Lang <mathias.lang@sociomantic.com> ---
Note: Only when compiled with `-de`.

They are two things at play here:

- First, when the compiler encounter an error, it 'poison' the AST node. That can lead to wrong error messages in places not adjusted to deal with the poisoning.

- Second, the compiler treat a non-fatal error (e.g. a warning when `-w` is provided or a deprecation when `-de` is provided) as a fatal one. This can have extremely dangerous consequences, e.g. the following will still compiles, just have different behaviour:

```
class Deprecated
{
    int j;
    this (T) (T i)
    {
        this.j = (i, T.init);
    }
}

template Foo (T) if (__traits(compiles, { T a = new T(42); }))
{
    enum Foo = "First instance";
}

template Foo (T) if (!__traits(compiles, { T a = new T(42); }))
{
    enum Foo = "Second instance";
}

pragma(msg, Foo!(Deprecated));
```

The second bug is well known, so I suppose this ER is about the first point ?

--

https://issues.dlang.org/show_bug.cgi?id=16312 Marco Leise <Marco.Leise@gmx.de> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords|rejects-valid | --- Comment #2 from Marco Leise <Marco.Leise@gmx.de> --- This report is about the first point, yes. Even if treated as an error, "deprecated" means the compiler can still handle the situation. I suggest, not to poison the AST for "deprecated as error" and "warning as error", but just print the error and continue compilation as normal. (And return -1 from main.) Does that seem feasible? --

https://issues.dlang.org/show_bug.cgi?id=16312 --- Comment #3 from Marco Leise <Marco.Leise@gmx.de> --- I just got the overlapping fields error after a bunch of "undefined identifier" errors. So it doesn't only happen after deprecated features are used. It happens with both dmd 2.069 and 2.071.1 at least. Other compilers were not tested. --

https://issues.dlang.org/show_bug.cgi?id=16312 Iain Buclaw <ibuclaw@gdcproject.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Priority|P1 |P3 --

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