This flag is a GNU extension, and would cause misleading test failures
on other platforms where this extension is not available. However, the
necessity to switch line endings is only required on Windows when
testing. We could use sed to canonicalize line endings before comparing,
but that may cause higher amounts of filesystem traffic on Windows which
would slow down testing.
Instead, move the substitution for diff in SourceKit's lit.local.cfg up
to the top level, and conditionalize the substitution which has the flag
on Windows, but not on other platforms (where it should not be required).
This adjusts the test diffing to ignore the whitespace changes across
different platforms. `raw_fd_ostream` will write out `OF_Text` files
with the platform's line endings, which may differ from the source
file's.
This converts the instances of the pattern for which we have a proper
substitution in lit. This will make it easier to replace it
appropriately with Windows equivalents.
The clang::RewriteBuffer can do weird things when seeing multiple
replacements where the replacement text is one character longer or
one character shorter than the range it is replacing.
rdar://problem/32234525
