[FileCheck] Annotate input dump (5/7)

This patch implements input annotations for diagnostics enabled by -v,
which report good matches for directives.  These annotations mark
match ranges using `^~~`.

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)
  - X~~    marks search range when no match is found, such as:
           - CHECK-NEXT not found (error)
  - ?      marks fuzzy match when no match is found
  - colors success, error, fuzzy match, unmatched input

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

$ FileCheck -v -dump-input=always check3 < input3 |& sed -n '/^<<<</,$p'
<<<<<<
         1: abc foobar def
check:1     ^~~
not:2           !~~~~~     error: no match expected
check:3                ^~~
>>>>>>

$ cat check3
CHECK:     abc
CHECK-NOT: foobar
CHECK:     def

$ cat input3
abc foobar def
```

-vv enables these annotations for FileCheck's implicit EOF patterns as
well.  For an example where EOF patterns become relevant, see patch 7
in this series.

If colors are enabled, `^~~` is green to suggest success.

-v plus color enables highlighting of input text that has no final
match for any expected pattern.  The highlight uses a cyan background
to suggest a cold section.  This highlighting can make it easier to
spot text that was intended to be matched but that failed to be
matched in a long series of good matches.

CHECK-COUNT-<num> good matches are another case where there can be
multiple match results for the same directive.

Reviewed By: george.karpenkov, probinson

Differential Revision: https://reviews.llvm.org/D53897

llvm-svn: 349422

0 files changed, 0 insertions, 0 deletions