Start capitalizing on some of the new diagnostic machinery in a few different ways:
- When mining constraints for type information, utilize constraints "favored" by the overload resolution process.
- When printing type variables, if the variable was created by opening a literal expression, utilize the literal
default type or conformance if possible.
- Utilize syntactic information when crafting diagnostics:
- If the constraint miner can produce a better diagnostic than the recorded failure, diagnose via constraints.
- Factor in the expression kind when choosing which types to include in a diagnostic message.
- Start customizing diagnostics based on the amount of type data available.
What does all this mean?
- Fewer type variables leaking into diagnostic messages.
- Far better diagnostics for overload resolution failures. Specifically, we now print proper argument type data
for failed function calls.
- No more "'Foo' is not convertible to 'Foo'" error messages
- A greater emphasis on type data means less dependence on the ordering of failed constraints. This means fewer
inscrutable diagnostics complaining about 'UInt8' when all the constituent expressions are of type Float.
So we still have a ways to go, but these changes should greatly improve the number of head-scratchers served up
by the type checker.
These changes address the following radars:
rdar://problem/17618403
rdar://problem/17559042
rdar://problem/17007456
rdar://problem/17559042
rdar://problem/17590992
rdar://problem/17646988
rdar://problem/16979859
rdar://problem/16922560
rdar://problem/17144902
rdar://problem/16616948
rdar://problem/16756363
rdar://problem/16338509
Swift SVN r20927
Modify TypeBase::getRValueType to structurally convert lvalues embedded in tuple and paren types. Inside the constraint solver, coerce types to rvalues based on the structural 'isLValueType' test rather than shallow 'is<LValueType>' checking. Fixes <rdar://problem/17507421>, but exposes an issue with call argument matching and lvalues <rdar://problem/17786730>.
Swift SVN r20442
Also:
- merge the test/decl/func/functions_new.swift testcase into test/Sema/immutability.swift,
where the bulk of similar tests are.
- Move the type checking logic for 'dynamic' out of ValidateAttrs into TypeCheckAttrs
- Change the encoding for 'override' to 49 so that stuff vbr's so much more densely :-)
Swift SVN r20006
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
JoeP helped tweak things to ensure that pointer conversions are still
considered, but we no longer need the disjunction on InOutExprs to accommodate
user-defined inout conversions.
This causes some regressions in error reporting:
<rdar://problem/17489983> inout type mismatches complain about '@lvalue inout T'
<rdar://problem/17489894> inout not rejected as operand to assignment operator
Swift SVN r19306
This reverts commit r19085, which broke the following tests.
Swift :: Constraints/super_constructor.swift
Swift :: expr/postfix/dot/init_ref_delegation.swift
Swift SVN r19098
var decls. I was originally intending to use this for argument lists, but I
don't think that's a great direction to go anymore.
In any case, it seems uncontroversial to enforce immutability on foreach
enumation patterns, so I did that (see testcase)
Swift SVN r11124
