Previously we could allow some invalid coercions to
sneak past Sema. In most cases these would either
cause crashes later down the pipeline or
miscompiles. However, for coercions between
collections, we emitted somewhat reasonable code
that performed a force cast.
This commit aims to preserve compatibility with
those collection coercions that previously
compiled, and emits a warning telling the user to
use either 'as?' or 'as!' instead.
This helps to avoid allocating new type variables (which shouldn't be done regardless)
to store parameter indices when `missing arguments` diagnostic is used by other diagnostics.
Instead of always applying solution back to constraint system
before diagnostics, let's pass solution directly to `ConstaintFix::diagnose`
method to be used by `FailureDiagnostic` which paves a way for
stateless diagnostics.
It's done by first retrieving all generic parameters from each solution,
filtering boundings into distrinct set and diagnosing any differences.
For example:
```swift
func foo<T>(_: T, _: T) {}
func bar(x: Int, y: Float) {
foo(x, y)
}
```
diagnosing failures in applySolutionFixes, coalesce fixes and
diagnose failures in one method on ConstraintFix.
This eliminates the need for the `DefaultGenericArgument` fix (which
was renamed from `ExplicitlySpecifyGenericArguments`) to have an
array of missing parameters, which was only used when the fixes were
coalesced. Instead, the coalesced arguments are used to create the
`MissingGenericArgumentsFailure` diagnostic directly.
Diagnose ephemeral conversions that are passed to @_nonEphemeral
parameters. Currently, this defaults to a warning with a frontend flag
to upgrade to an error. Hopefully this will become an error by default
in a future language version.
By convention, most structs and classes in the Swift compiler include a `dump()` method which prints debugging information. This method is meant to be called only from the debugger, but this means they’re often unused and may be eliminated from optimized binaries. On the other hand, some parts of the compiler call `dump()` methods directly despite them being intended as a pure debugging aid. clang supports attributes which can be used to avoid these problems, but they’re used very inconsistently across the compiler.
This commit adds `SWIFT_DEBUG_DUMP` and `SWIFT_DEBUG_DUMPER(<name>(<params>))` macros to declare `dump()` methods with the appropriate set of attributes and adopts this macro throughout the frontend. It does not pervasively adopt this macro in SILGen, SILOptimizer, or IRGen; these components use `dump()` methods in a different way where they’re frequently called from debugging code. Nor does it adopt it in runtime components like swiftRuntime and swiftReflection, because I’m a bit worried about size.
Despite the large number of files and lines affected, this change is NFC.
If there are more arguments than parameters, let's fix this by
ignoring (if possible) or removing extraneous arguments. Ignored
arguments could default to `Any` if they don't get any other
contextual type.
Introduce a fix/diagnostic when there is a contextual mismatch
between source and destination types of the assignment e.g.:
```swift
var x: Int = 0
x = 4.0 // destination expects an `Int`, but source is a `Double`
```
Instead of storing contextual function type in the fix/diagnostic,
let's fetch it from context (solution and/or locator) because it's
only used when it is a trailing closure missing some arguments anyway.
