`_` or discard assignment expression should only be used on the left-hand
side of the assignment expression. Incorrect uses are easy to detect during
constraint generation which also allows us to avoid complications related
to other diagnostics when `_` is used incorrectly.
Reverts apple/swift#30006. It caused a regression that we'd like to address before re-landing:
```swift
struct X {
var cgf: CGFloat
}
func test(x: X?) {
let _ = (x?.cgf ?? 0) <= 0.5
}
```
This reverts commit 0a6b444b49.
This reverts commit ed255596a6.
This reverts commit 3e01160a2f.
This reverts commit 96297b7e39.
Resolves: rdar://problem/60185506
Prioritize type mismatches over conformance failures when stdlib
types are involved because it wouldn't be appropriate to suggest
to add such a conformance, so the problem is most likely related
to something else e.g. other overload choice has a better fix.
Consider following example:
```swift
struct S {
init(_: Double) {}
init<T: BinaryInteger>(_: T) {}
}
_ = S(Double("0"))
```
In cases like that it's better to prefer failable initializer
which takes a `String` and returns `Double?` and diagnose a
problem related to missing optional unwrap instead of missing
conformances related to a `String` argument of other `Double`
initializer just because it returns a concrete type.
Since `simplifyRestrictedConstraintImpl` has both parent types and
does nested type matching it's a good place to diagnose top-level
contextual problems like mismatches in underlying types of optionals.
If a type variable representing "function type" is a hole
or it could be bound to some concrete type with a help of
a fix, let's propagate holes to the "input" type. Doing so
provides more information to upcoming argument and result matching.
* [Sema][Diagnostics] Add fixit for warning when inferring an undesirable type
* [Sema][Diagnostics] Generalize undesirable type warning to include arrays of empty tuples
https://bugs.swift.org/browse/SR-11511
All of the argument diagnostics have been ported to the new diagnostic
framework, so now is the time to remove `ArgumentMatcher` and the only
place where it was used - `diagnoseSingleCandidateFailures`.
Argument-to-Parameter mismatch handles conformance failures
related to arguments, so the logic in `MissingConformanceFailure`
which wasn't entirely correct is now completely obsolete.
Resolves: rdar://problem/56234611
When it comes to `@autoclosure` parameters we only detect and diagnose
mismatches related to invalid implicit conversions to pointer types. But
`@autoclosure` parameters just like regular ones can have type mismatches
as well which can be handled via recently introduced
`argument-to-parameter mismatch` fix.
Detect and diagnose a contextual mismatch between expected
collection element type and the one provided (e.g. source
of the assignment or argument to a call) e.g.:
```swift
let _: [Int] = ["hello"]
func foo(_: [Int]) {}
foo(["hello"])
```
We don't require or allow '&' for the mutable parameters in
operator calls, since we want to write 'x += 10' and not
'&x += 10'.
The constraint sovler accepted '&x += 10' though, and we had
a separate pass in MiscDiagnostics for rejecting it.
Instead, let's just reject this in the solver.
The main difficulty is that we must now be prepared to fail
certain OperatorArgumentConversion and ApplicableFunction
constraints even when both the LHS and RHS types are equal.
For context, String, Nil, and Bool already behave this way.
Note: Before it used to construct (call, ... (integer_literal)), and the
call would be made explicit / implicit based on if you did eg: Int(3) or
just 3. This however did not translate to the new world so this PR adds
a IsExplicitConversion bit to NumberLiteralExpr. Some side results of
all this are that some warnings changed a little and some instructions are
emitted in a different order.
when skipping to the end of the interpolated expression.
i.e. Skip the comment as a comment.
Previously, ')' or '"' in comment in interpolated expression used to
cause assertion failure or mis-compilation in no-assert build.
rdar://problem/20289969
This makes diagnostics more verbose and accurate, because
it's possible to distinguish how many parameters there are
based on the message itself.
Also there are multiple diagnostic messages in a format of
`<descriptive-kind> <decl-name> ...` that get printed as
e.g. `subscript 'subscript'` if empty labels are omitted.
If generic parameter associated with missing conformance comes
from different context diagnose the problem as "referencing" a
specific declaration from affected type.
Instead of simply pointing out which type had conformance failures,
let's use affected declaration instead, which makes diagnostics much
richer e.g.
```
'List<[S], S.Id>' requires that 'S.Id' conform to 'Hashable'
```
versus
```
initializer 'init(_🆔)' requires that 'E' conform to 'Hashable' [with 'E' = 'S.Id']
```
Since latter message uses information about declaration, it can also
point to it in the source. That makes is much easier to understand when
problem is related to overloaded (function) declarations.
Since constraint solver has been improved to diagnose more problems
via "fixes", sometimes applying fixes might lead to producing solutions
which are completely ambiguous when compared to each other, and/or are
incomparable, which leads to `findBestSolutions` erasing all of them
while trying to compute best "partial" solution, which is incorrect.
Resolves: rdar://problem/42678836
And provide better semantic background by surrounding 'nil' in ticks when it is referred to as a value
Added missing tests for certain cases involving nil capitalization
* [Diagnostics] SR-7445 Improve diagnostics for assignment failures
* modified messages for assignments to function calls,
modified messages for assignments to methods.
removed comment for resolved radar.
* removed extra line and braces
* added tests for assignment_lhs_is_apply_expression
eliminated redundant literal check which is always invoked before call
reverted 'cannot assign to value' for literal assignments in subexpressions
* Complemented assigning to literal tests & reverted to 'cannot asign to value' for methods (was 'cannot assign to member')
* removed extra tabs
* eliminated one more accidental spacing
* Update CSDiag.cpp
* added highlighting, fixed & rechecked tests
* added highlighting for complex expressions involving assigning to literals
Resolves: [SR-7445](https://bugs.swift.org/browse/SR-7445)
