[FileCheck] Annotate input dump (7/7)

This patch implements annotations for diagnostics reporting CHECK-NOT
failed matches.  These diagnostics are enabled by -vv.  As for
diagnostics reporting failed matches for other directives, these
annotations mark the search ranges using `X~~`.  The difference here
is that failed matches for CHECK-NOT are successes not errors, so they
are green not red when colors are enabled.

For example:

```
$ FileCheck -dump-input=help
The following description was requested by -dump-input=help to
explain the input annotations printed by -dump-input=always and
-dump-input=fail:

  - L:     labels line number L of the input file
  - T:L    labels the only match result for a pattern of type T from line L of
           the check file
  - T:L'N  labels the Nth match result for a pattern of type T from line L of
           the check file
  - ^~~    marks good match (reported if -v)
  - !~~    marks bad match, such as:
           - CHECK-NEXT on same line as previous match (error)
           - CHECK-NOT found (error)
           - CHECK-DAG overlapping match (discarded, reported if -vv)
  - X~~    marks search range when no match is found, such as:
           - CHECK-NEXT not found (error)
           - CHECK-NOT not found (success, reported if -vv)
           - CHECK-DAG not found after discarded matches (error)
  - ?      marks fuzzy match when no match is found
  - colors success, error, fuzzy match, discarded match, unmatched input

If you are not seeing color above or in input dumps, try: -color

$ FileCheck -vv -dump-input=always check5 < input5 |& sed -n '/^<<<</,$p'
<<<<<<
         1: abcdef
check:1     ^~~
not:2          X~~
         2: ghijkl
not:2       ~~~
check:3        ^~~
         3: mnopqr
not:4       X~~~~~
         4: stuvwx
not:4       ~~~~~~
         5:
eof:4       ^
>>>>>>

$ cat check5
CHECK: abc
CHECK-NOT: foobar
CHECK: jkl
CHECK-NOT: foobar

$ cat input5
abcdef
ghijkl
mnopqr
stuvwx
```

Reviewed By: george.karpenkov, probinson

Differential Revision: https://reviews.llvm.org/D53899

llvm-svn: 349424

0 files changed, 0 insertions, 0 deletions