By splitting out the expression used to allocate 'this' (which exists
in the AST but cannot be written in the Swift language proper), we
make it possible to emit non-allocating constructors for imported
Objective-C classes, which are the only classes that have an
allocate-this expression.
Swift SVN r3558
Note: this is an experiment.
When we're asked to render a diagnostic for a declaration that does
not have source information, pretty-print the declaration into a
buffer and synthesize a location pointing into that buffer. This gives
the illusion of Clang-style diagnostics where we have all of the
source headers, but without actually requiring that source location
information. It may prove useful or infuriating, but at the very least
it might help us understand how the importer works. Example:
cfuncs_diags.swift:14:7: error: no candidates found for call
exit(5)
~~~~^~~
cfuncs_diags.swift:6:6: note: found this candidate
func exit(_ : Float) {}
^
cfuncs.exit:1:6: note: found this candidate
func exit(_ : CInt)
^
Swift SVN r3434
