This eliminates UnicodeData.h from the public SwiftShims. A small
part of it remains as a private header, but everything else moves
into `@_extern(c)`.
Now accepted as
[SE-0489](https://github.com/ZevEisenberg/swift-evolution/blob/main/proposals/0489-codable-error-printing.md).
# To Do
- [x] confirm which version of Swift to use for the availability
annotations. Probably 6.3 at time of writing.
# Context
Re: [Swift forum
post](https://forums.swift.org/t/the-future-of-serialization-deserialization-apis/78585/77),
where a discussion about future serialization tools in Swift prompted
Kevin Perry to suggest that some proposed changes could actually be made
in today's stdlib.
# Summary of Changes
Conforms `EncodingError` and `DecodingError` to
`CustomDebugStringConvertible` and adds a more-readable
`debugDescription`.
# Future Directions
This is a pared-down version of some experiments I did in
[UsefulDecode](https://github.com/ZevEisenberg/UsefulDecode). The
changes in this PR are the best I could do without changing the public
interface of `DecodingError` and `EncodingError`, and without modifying
the way the `JSON`/`PropertyList` `Encoder`/`Decoder` in Foundation
generate their errors' debug descriptions.
In the above-linked
[UsefulDecode](https://github.com/ZevEisenberg/UsefulDecode) repo, when
JSON decoding fails, I go back and re-decode the JSON using
`JSONSerialization` in order to provide more context about what failed,
and why. I didn't attempt to make such a change here, but I'd like to
discuss what may be possible.
# Examples
To illustrate the effect of the changes in this PR, I removed my changes
to stdlib/public/core/Codable.swift and ran my new test cases again.
Here are the resulting diffs.
##
`test_encodingError_invalidValue_nonEmptyCodingPath_nilUnderlyingError`
### Before
`invalidValue(234, Swift.EncodingError.Context(codingPath:
[GenericCodingKey(stringValue: "first", intValue: nil),
GenericCodingKey(stringValue: "second", intValue: nil),
GenericCodingKey(stringValue: "2", intValue: 2)], debugDescription: "You
cannot do that!", underlyingError: nil))`
### After
`EncodingError.invalidValue: 234 (Int). Path: first.second[2]. Debug
description: You cannot do that!`
## `test_decodingError_valueNotFound_nilUnderlyingError`
### Before
`valueNotFound(Swift.String, Swift.DecodingError.Context(codingPath:
[GenericCodingKey(stringValue: "0", intValue: 0),
GenericCodingKey(stringValue: "firstName", intValue: nil)],
debugDescription: "Description for debugging purposes", underlyingError:
nil))`
### After
`DecodingError.valueNotFound: Expected value of type String but found
null instead. Path: [0].firstName. Debug description: Description for
debugging purposes`
## `test_decodingError_keyNotFound_nonNilUnderlyingError`
### Before
`keyNotFound(GenericCodingKey(stringValue: "name", intValue: nil),
Swift.DecodingError.Context(codingPath: [GenericCodingKey(stringValue:
"0", intValue: 0), GenericCodingKey(stringValue: "address", intValue:
nil), GenericCodingKey(stringValue: "city", intValue: nil)],
debugDescription: "Just some info to help you out", underlyingError:
Optional(main.GenericError(name: "hey, who turned out the lights?"))))`
### After
`DecodingError.keyNotFound: Key \'name\' not found in keyed decoding
container. Path: [0].address.city. Debug description: Just some info to
help you out. Underlying error: GenericError(name: "hey, who turned out
the lights?")`
## `test_decodingError_typeMismatch_nilUnderlyingError`
### Before
`typeMismatch(Swift.String, Swift.DecodingError.Context(codingPath:
[GenericCodingKey(stringValue: "0", intValue: 0),
GenericCodingKey(stringValue: "address", intValue: nil),
GenericCodingKey(stringValue: "city", intValue: nil),
GenericCodingKey(stringValue: "birds", intValue: nil),
GenericCodingKey(stringValue: "1", intValue: 1),
GenericCodingKey(stringValue: "name", intValue: nil)], debugDescription:
"This is where the debug description goes", underlyingError: nil))`
### After
`DecodingError.typeMismatch: expected value of type String. Path:
[0].address.city.birds[1].name. Debug description: This is where the
debug description goes`
## `test_decodingError_dataCorrupted_nonEmptyCodingPath`
### Before
`dataCorrupted(Swift.DecodingError.Context(codingPath:
[GenericCodingKey(stringValue: "first", intValue: nil),
GenericCodingKey(stringValue: "second", intValue: nil),
GenericCodingKey(stringValue: "2", intValue: 2)], debugDescription:
"There was apparently some data corruption!", underlyingError:
Optional(main.GenericError(name: "This data corruption is getting out of
hand"))))`
### After
`DecodingError.dataCorrupted: Data was corrupted. Path: first.second[2].
Debug description: There was apparently some data corruption!.
Underlying error: GenericError(name: "This data corruption is getting
out of hand")`
## `test_decodingError_valueNotFound_nonNilUnderlyingError`
### Before
`valueNotFound(Swift.Int, Swift.DecodingError.Context(codingPath:
[GenericCodingKey(stringValue: "0", intValue: 0),
GenericCodingKey(stringValue: "population", intValue: nil)],
debugDescription: "Here is the debug description for value-not-found",
underlyingError: Optional(main.GenericError(name: "these aren\\\'t the
droids you\\\'re looking for"))))`
### After
`DecodingError.valueNotFound: Expected value of type Int but found null
instead. Path: [0].population. Debug description: Here is the debug
description for value-not-found. Underlying error: GenericError(name:
"these aren\\\'t the droids you\\\'re looking for")`
##
`test_encodingError_invalidValue_emptyCodingPath_nonNilUnderlyingError`
### Before
`invalidValue(345, Swift.EncodingError.Context(codingPath: [],
debugDescription: "You cannot do that!", underlyingError:
Optional(main.GenericError(name: "You really cannot do that"))))`
### After
`EncodingError.invalidValue: 345 (Int). Debug description: You cannot do
that!. Underlying error: GenericError(name: "You really cannot do
that")`
## `test_decodingError_typeMismatch_nonNilUnderlyingError`
### Before
`typeMismatch(Swift.String, Swift.DecodingError.Context(codingPath:
[GenericCodingKey(stringValue: "0", intValue: 0),
GenericCodingKey(stringValue: "address", intValue: nil),
GenericCodingKey(stringValue: "1", intValue: 1),
GenericCodingKey(stringValue: "street", intValue: nil)],
debugDescription: "Some debug description", underlyingError:
Optional(main.GenericError(name: "some generic error goes here"))))`
### After
`DecodingError.typeMismatch: expected value of type String. Path:
[0].address[1].street. Debug description: Some debug description.
Underlying error: GenericError(name: "some generic error goes here")`
## `test_encodingError_invalidValue_emptyCodingPath_nilUnderlyingError`
### Before
`invalidValue(123, Swift.EncodingError.Context(codingPath: [],
debugDescription: "You cannot do that!", underlyingError: nil))`
### After
`EncodingError.invalidValue: 123 (Int). Debug description: You cannot do
that!`
## `test_decodingError_keyNotFound_nilUnderlyingError`
### Before
`keyNotFound(GenericCodingKey(stringValue: "name", intValue: nil),
Swift.DecodingError.Context(codingPath: [GenericCodingKey(stringValue:
"0", intValue: 0), GenericCodingKey(stringValue: "address", intValue:
nil), GenericCodingKey(stringValue: "city", intValue: nil)],
debugDescription: "How would you describe your relationship with your
debugger?", underlyingError: nil))`
### After
`DecodingError.keyNotFound: Key \'name\' not found in keyed decoding
container. Path: [0]address.city. Debug description: How would you
describe your relationship with your debugger?`
## `test_decodingError_dataCorrupted_emptyCodingPath`
### Before
`dataCorrupted(Swift.DecodingError.Context(codingPath: [],
debugDescription: "The given data was not valid JSON", underlyingError:
Optional(main.GenericError(name: "just some data corruption"))))`
### After
`DecodingError.dataCorrupted: Data was corrupted. Debug description: The
given data was not valid JSON. Underlying error: GenericError(name:
"just some data corruption")`
##
`test_encodingError_invalidValue_nonEmptyCodingPath_nonNilUnderlyingError`
### Before
`invalidValue(456, Swift.EncodingError.Context(codingPath:
[GenericCodingKey(stringValue: "first", intValue: nil),
GenericCodingKey(stringValue: "second", intValue: nil),
GenericCodingKey(stringValue: "2", intValue: 2)], debugDescription: "You
cannot do that!", underlyingError: Optional(main.GenericError(name: "You
really cannot do that"))))`
### After
`EncodingError.invalidValue: 456 (Int). Path: first.second[2]. Debug
description: You cannot do that!. Underlying error: GenericError(name:
"You really cannot do that")`
In the comments it's stated that these errnos can't really occur for
the implementation, but unfortunately they have been seen in some
scenarios. To aide in debugging, it'd be nice to at least have the
errno in the error message.
Users frequently run into a missing runtime symbol for Cxx exceptions
(`_swift_exceptionPersonality`) when mixing Embedded Swift and Cxx with
exceptions enabled. This leads to a confusing an hard to debug linker
error. This commit adds an implementation of this function to the
Embedded Swift runtime which simply fatal errors if a cxx exception is
caught in a Swift frame.
Issue: rdar://164423867
Issue: #85490
The `color=tty` setting was checking `stdout` to see if it was a TTY, but
we may be using `stderr`, in which case it's easy to end up with coloured
output in a file we're redirecting to. Fix it to check the selected
output instead.
rdar://164624364
Adds an overload of `_DebuggerSupport.stringForPrintObject` which takes a pointer and mangled typename as arguments. This will be used to improve performance and resilience of `po` in lldb.
The pointer and mangled typename are used to construct an `Any` value, which is then passed into the primary implementation of `stringForPrintObject`.
This allows calling `stringForPrintObject` without having to first construct a context that contains all necessary Swift modules. This will improve speed, and also resilience when modules cannot be loaded for whatever reason.
rdar://158968103
Code using the outline heap storage path will crash and burn because
support is incomplete. But at least inline storage existential
inhabitants should compile and run.
