Specialize and improve the "downcast only unwraps optionals"
diagnostic to provide specific diagnostics + Fix-Its for the various
casts of forced cast, conditional cast, and "isa" check. Specifically:
* With a forced cast, customize the diagnostic. We still insert the
appropriate number of !'s, but now we remove the 'as! T' (if an
implicit conversion would suffice) or replace the 'as!' with 'as'
(if we still need a bridge)
* With a conditional cast, only emit a diagnostic if we're removing
just one level of optional. In such cases, we either have a no-op
(an implicit conversion would do) or we could just use 'as' to the
optional type, so emit a customized warning to do that. If we are
removing more than one level of optional, don't complain:
conditional casts can remove optionals. Add the appropriate Fix-Its
here.
* With an 'is' expression, only emit a diagnostic if we're removing
just one level of optional. In this case, the 'is' check is
equivalent to '!= nil'. Add a Fix-It for that.
Across the board, reduce the error to a warning. These are
semantically-well-formed casts, it's just that they could be written
better.
Fixes rdar://problem/28856049 and rdar://problem/22275685.
This commit defines the ‘Any’ keyword, implements parsing for composing
types with an infix ‘&’, and provides a fixit to convert ‘protocol<>’
- Updated tests & stdlib for new composition syntax
- Provide errors when compositions used in inheritance.
Any is treated as a contextual keyword. The name ‘Any’
is used emit the empty composition type. We have to
stop user declaring top level types spelled ‘Any’ too.
Previously, a type that conformed to 'Error' could not be bridged to
NSError directly. Rather, one would have to go through the 'Error'
protocol, e.g.,
myErrorValue as Error as NSError
rather than
myErrorValue as NSError
Make the latter work.
allowing these failures to hook into other diagnostic goodies (e.g. the
"did you mean to use '!' or '?'?" cases showing in the testsuite). That said,
by itself this doesn't have a huge impact, but avoids regressions with other
pending changes.
Swift SVN r31289
which we have a contextual type that was the failure reason. These are a bit
longer but also more explicit than the previous diagnostics.
Swift SVN r30669
If a generic parameter is not referred to from a function signature, it can never be inferred and thus such a function can never be invoked.
We now produce the following error:
generic parameter 'T' is not used in function signature
func f8<T> (x: Int) {}
This commit takes Jordan't comments on r28181 into account:
- it produces a shorter error message
- it does not change the compiler_crashers_fixed test and add a new expected error instead
Swift SVN r28194
If a generic parameter is not referred to from a function signature, it can never be inferred and thus such a function can never be invoked.
We now produce the following error:
There is no way to infer the generic parameter 'T' if it is not used in function signature
func f8<T> (x: Int) {}
^
Swift SVN r28181
Most tests were using %swift or similar substitutions, which did not
include the target triple and SDK. The driver was defaulting to the
host OS. Thus, we could not run the tests when the standard library was
not built for OS X.
Swift SVN r24504
Previously the "as" keyword could either represent coercion or or forced
downcasting. This change separates the two notions. "as" now only means
type conversion, while the new "as!" operator is used to perform forced
downcasting. If a program uses "as" where "as!" is called for, we emit a
diagnostic and fixit.
Internally, this change removes the UnresolvedCheckedCastExpr class, in
favor of directly instantiating CoerceExpr when parsing the "as"
operator, and ForcedCheckedCastExpr when parsing the "as!" operator.
Swift SVN r24253
This prevented metatype casts and other kinds of cast that could be allowed from being accepted. Keep the subtype constraint if we're casting between generic class types with open type variables, because it can provide context to deduce type arguments in this case. This causes a regression in test/Constraints/members.swift that uses 'as' as a coercion, but we're planning to disambiguate cast/coercion syntax soon, which should fix that issue.
Swift SVN r23303
It doesn't make sense to try to limit them in most cases, because there may be protocol conformances we don't know about statically in the dynamic program. Relax casts that always succeed or fail to be a warning instead of an error.
Swift SVN r23298
This only tackles the protocol case (<rdar://problem/17510790>); it
does not yet generalize to an arbitrary "class" requirement on either
existentials or generics.
Swift SVN r19896
There's a bit of a reshuffle of the ExplicitCastExpr subclasses:
- The existing ConditionalCheckedCastExpr expression node now represents
"as?".
- A new ForcedCheckedCastExpr node represents "as" when it is a
downcast.
- CoerceExpr represents "as" when it is a coercion.
- A new UnresolvedCheckedCastExpr node describes "as" before it has
been type-checked down to ForcedCheckedCastExpr or CoerceExpr. This
wasn't a strictly necessary change, but it helps us detangle what's
going on.
There are a few new diagnostics to help users avoid getting bitten by
as/as? mistakes:
- Custom errors when a forced downcast (as) is used as the operand
of postfix '!' or '?', with Fix-Its to remove the '!' or make the
downcast conditional (with as?), respectively.
- A warning when a forced downcast is injected into an optional,
with a suggestion to use a conditional downcast.
- A new error when the postfix '!' is used for a contextual
downcast, with a Fix-It to replace it with "as T" with the
contextual type T.
Lots of test updates, none of which felt like regressions. The new
tests are in test/expr/cast/optionals.swift.
Addresses <rdar://problem/17000058>
Swift SVN r18556
Provide distinct syntax 'a as T' for coercions and 'a as! T' for unchecked downcasts, and add type-checker logic specialized to coercions and downcasts for these expressions. Change the AST representation of ExplicitCastExpr to keep the destination type as a TypeLoc rather than a subexpression, and change the names of the nodes to UncheckedDowncast and UncheckedSuperToArchetype to make their unchecked-ness explicit and disambiguate them from future checked casts.
In order to keep the changes staged, this doesn't yet affect the T(x) constructor syntax, which will for the time being still perform any construction, coercion, or cast.
Swift SVN r4498
