When using `@DebugDescription`, only allow use of [LLDB Summary
Strings](https://lldb.llvm.org/use/variable.html#summary-strings) syntax from
`lldbDescription` properties. When `@DebugDescription` is applied to existing
`debugDescription` properties, escape any `$`, as the output of `debugDescription` is
never interpreted by LLDB.
Depends on #75305
From feedback, replace the name `_debugDescription`, which was confusing because of the
underscore, with `lldbDescription`. This new name also indicates that this property may
contain [LLDB Summary Strings](https://lldb.llvm.org/use/variable.html#summary-strings).
On windows (PECOFF), the `static let` properties produced by `DebugDescriptionMacro`
are not constants, and as a result the `@_section` macro cannot be applied. The error
message is:
> global variable must be a compile-time constant to use `@_section` attribute
Until this issue is addressed, DebugDescriptionMacro is disabled for windows targets.
The data emitted by `DebugDescriptionMacro` is constant. For that reason, it was placed
in `__DATA_CONST`. However, this causes a problem with the linker, which emits an error
if the `__DATA_CONST` segment is _not_ marked `SG_READ_ONLY`.
After discussion, it was pointed out that if the constant data has no fixups, then it
can and should be in the the `__TEXT` segment. The `__DATA_CONST` segment is for data
that is essentially constant but contains dyld fixups.
Fixes the way `DebugDescriptionMacro` produces a regex type name.
The problem was use of backslash escapes that weren't sufficiently escaped. They needed
to be double escaped. To avoid this trap, the regexes now use `[.]` to match a dot,
instead of the more conventional `\.` syntax.
Some data types cannot modify their `description` or `debugDescription` properties, as
modification to those properties could result in breakage to their users. To support
these conditions, `DebugDescriptionMacro` should support and prioritize an independent
property (one that that is not being reused).
This change adds support for `_debugDescription`. The macro will now prioritize the
description properties in this order:
1. `_debugDescription`
2. `debugDescription`
3. `debugDescription`
rdar://120498021
Implementation of the DebugDescription macro pitched on the forums:
https://forums.swift.org/t/pitch-debug-description-macro/67711. In this initial commit,
the macro is named `_DebugDescription` to indicate it's internal use at this time,
pending Swift Evolution.
rdar://115180949
