On Thursday, 24 December 2020 at 18:05:30 UTC, Mathias LANG wrote:
On Thursday, 24 December 2020 at 11:38:11 UTC, Paolo Invernizzi
wrote:
The point is that the deprecation is coming from an external
library, it would be great to have the precise instantiation
point in that source code, so I was wondering if that dmd
improvement [1] should print a more detailed trace.
[1]
https://dlang.org/changelog/2.095.0.html#deprecation-context
It does print a detailed stack trace (up to the first symbol
that is not a template) if you don't use `-de`. If you use
`-de`, since the checks in Phobos are
`is(typeof(n.toString()))` or `__traits(compiles,
n.toString())`, then it just changes whether or not the code
compiles, and as a result changes the output of the program. A
trivial example:
```
import std.stdio, std.typecons;
struct Foo {
deprecated string toString() const { return "Oops"; }
}
void main () { writefln("%s", Foo.init); }
```
Will print, with v2.094.2 or before (dmd -run):
```
/usr/local/opt/dmd/include/dlang/dmd/std/format.d(3921):
Deprecation: function foo.Foo.toString is deprecated
/usr/local/opt/dmd/include/dlang/dmd/std/format.d(4053):
Deprecation: function foo.Foo.toString is deprecated
Oops
```
Not great. If you use `dmd -de -run`, you'll get:
```
Foo()
```
Notice the deprecations are gone, but so is the usage of the
`toString` method. Using DMD v2.095.0-beta.1 with `-de` should
give you the same output, but without `-de`:
```
% ~/dlang/dmd-2.095.0-beta.1/osx/bin/dmd -run foo.d
/Users/geod24/dlang/dmd-2.095.0-beta.1/osx/bin/../../src/phobos/std/format.d(3921):
Deprecation: function foo.Foo.toString is deprecated
/Users/geod24/dlang/dmd-2.095.0-beta.1/osx/bin/../../src/phobos/std/format.d(4420):
instantiated from here: hasToString!(Foo, char)
/Users/geod24/dlang/dmd-2.095.0-beta.1/osx/bin/../../src/phobos/std/format.d(4053):
Deprecation: function foo.Foo.toString is deprecated
/Users/geod24/dlang/dmd-2.095.0-beta.1/osx/bin/../../src/phobos/std/format.d(4430):
instantiated from here: formatObject!(LockingTextWriter, Foo, char)
/Users/geod24/dlang/dmd-2.095.0-beta.1/osx/bin/../../src/phobos/std/format.d(1875):
instantiated from here: formatValueImpl!(LockingTextWriter, Foo, char)
/Users/geod24/dlang/dmd-2.095.0-beta.1/osx/bin/../../src/phobos/std/format.d(576):
instantiated from here: formatValue!(LockingTextWriter, Foo, char)
/Users/geod24/dlang/dmd-2.095.0-beta.1/osx/bin/../../src/phobos/std/stdio.d(1661):
... (1 instantiations, -v to show) ...
/Users/geod24/dlang/dmd-2.095.0-beta.1/osx/bin/../../src/phobos/std/stdio.d(4271):
instantiated from here: writefln!(char, Foo)
foo.d(5): instantiated from here: writefln!(char, Foo)
Oops
```
So the feature works as intended, however `-de` is a dangerous
trap, as it changes what is instantiated.
Thanks Matias,
My point is that the result without -de is
---
/Users/pinver/dlang/dmd-2.095.0-beta.1/osx/bin/dmd -i -g -debug
src/foo.d
/Users/pinver/dlang/dmd-2.095.0-beta.1/osx/bin/../../src/phobos/std/traits.d(3727):
Deprecation: function std.typecons.Nullable!long.Nullable.get_ is deprecated -
Implicit conversion with alias Nullable.get this will be removed after 2.096.
Please use .get explicitly.
/Users/pinver/dlang/dmd-2.095.0-beta.1/osx/bin/../../src/phobos/std/traits.d(3727):
Deprecation: function std.typecons.Nullable!short.Nullable.get_ is deprecated
- Implicit conversion with alias Nullable.get this will be removed after 2.096.
Please use .get explicitly.
---
Which unfortunately is pretty useless in my case ...
