[Diagnostics] Transfer previously resolved types directly from expressions

[xedin]

While trying to diagnose the problem with previously type-checked
sub-expression, use its type-checked variant as a source of type
information, instead of transferring from its original constraint system,
because if expression was type-checked successfully it would
have all of the required information in AST, and that doesn't
rely on associated constraint system being present.

Resolves: rdar://problem/42056741

[xedin]

@swift-ci please test

[rudkx]

LGTM. That code was required at one point but I suspect we're caching more types in enough places that it's now more of a problem than a solution.

You can remove the tranferExprTypes() method at this point, too.

[xedin]

@swift-ci please test source compatibility

[xedin]

Removing transferExprTypes in the separate commit so it could be reverted if needed.

[xedin]

@swift-ci please test

[xedin]

@swift-ci please test source compatibility

[slavapestov]

Can you add the type checker test case as well? IIRC it didn’t crash on master but still emitted a duplicate diagnostic.

[xedin]

The example I've added doesn't crash without code-completion because that triggers diagnostics differently, I couldn't make it crash without using code completion, and it also doesn't produce duplicate diagnostics either, you might be thinking of a different example...

[swift-ci]

Build failed
Swift Test Linux Platform
Git Sha - 11e1d13

[xedin]

3 LLDB tests are failing again:

23:22:02 FAIL: test_swift_conditional_breakpoint_dwarf (lang/swift/conditional_breakpoints/TestSwiftConditionalBreakpoint.py)
23:22:02 FAIL: test_swift_stepping_dwarf (lang/swift/stepping/TestSwiftStepping.py)
23:22:02 FAIL: test_swift_struct_init_dwarf (lang/swift/struct_init_display/TestSwiftStructInit.py)

[xedin]

@swift-ci please test Linux platform

[xedin]

@swift-ci please test

[xedin]

@swift-ci please test source compatibility

[swift-ci]

Build failed
Swift Test OS X Platform
Git Sha - 939f6d4

[xedin]

@swift-ci please test macOS platform