SE-390 concluded with choosing the keyword discard rather than forget for
the statement that disables the deinit of a noncopyable type. This commit
adds parsing support for `discard self` and adds a deprecation warning for
`_forget self`.
rdar://108859077
Diagnose situations where value pack is referenced without an explicit 'each':
```
func compute<each T>(_: repeat each T) {}
func test<each T>(v: repeat each T) {
repeat compute(v) // should be `repeat compute(each v)`
}
```
- Simplify the fix locator when looking for a
fix already present in a pattern match, this
avoids us emitting both a diagnostic for the
argument conversion, and for a conformance failure.
- Include tuples in the diagnostic logic where
we emit a generic "operator cannot be applied"
diagnostic, as a conformance diagnostic is
unlikely to be helpful in that case.
Does not fix the fix-it. The current fix it will be left as a stop-gap solution and we can hopefully update this fix it in the near future to actually plop in a for loop (too much work for this PR though).
Diagnose situation when a single argument to tuple type is passed to
a value pack expansion parameter that expects distinct N elements:
```swift
struct S<each T> {
func test(x: Int, _: repeat each T) {}
}
S<Int, String>().test(x: 42, (2, "b"))
```
When placeholder type appears in an editor placeholder i.e.
`<#T##() -> _#>` we rely on the parser to produce a diagnostic
about editor placeholder and glance over all placeholer type
inference issues.
Resolves: rdar://106621760
Currently, this is staged in as `_forget`,
as part of SE-390. It can only be used on
`self` for a move-only type within a consuming
method or accessor. There are other rules, see
Sema for the details.
A `forget self` really just consumes self and
performs memberwise destruction of its data.
Thus, the current expansion of this statement
just reuses what we inject into the end of a
deinit.
Parsing of `forget` is "contextual".
By contextual I mean that we do lookahead to
the next token and see if it's identifier-like.
If so, then we parse it as the `forget` statement.
Otherwise, we parse it as though "forget" is an
identifier as part of some expression.
This way, we won't introduce a source break for
people who wrote code that calls a forget
function.
This should make it seamless to change it from
`_forget` to `forget` in the future.
resolves rdar://105795731
Provide ASTWalker with a customization point to specify whether to
check macro arguments (which are type checked but never emitted), the
macro expansion (which is the result of applying the macro and is
actually emitted into the source), or both. Provide answers for the
~115 different ASTWalker visitors throughout the code base.
Fixes rdar://104042945, which concerns checking of effects in
macro arguments---which we shouldn't do.
