[llvm-dev] [FileCheck] Fix --strict-whitespace --match-full-lines

[Tom de Vries via llvm-dev]

Hi,

this patch fixes a problem with leading/trailing whitespace matching for 
FileCheck --strict-whitespace --match-full-lines.

Consider a text file:
...
$ cat DUMP
bla1
bla2
  bla3
bla4
  bla5
...

with some leading and trailing spaces, made more visible like this:
...
$ sed 's/ /_/g' DUMP
bla1
bla2
_bla3
bla4_
_bla5_
...

and a FileCheck file CHECK to match DUMP:
...
$ cat CHECK
// CHECK-LABEL:bla1
// CHECK-NEXT:bla2
// CHECK-NEXT: bla3
// CHECK-NEXT:bla4
// CHECK-NEXT: bla5
...

with whitespace made more visible like this:
...
$ sed 's/ /_/g' CHECK
//_CHECK-LABEL:bla1
//_CHECK-NEXT:bla2
//_CHECK-NEXT:_bla3
//_CHECK-NEXT:bla4_
//_CHECK-NEXT:_bla5_
...

When trying the match, it fails:
...
$ cat DUMP | FileCheck CHECK --strict-whitespace --match-full-lines
CHECK:3:16: error: expected string not found in input
// CHECK-NEXT: bla3
                ^
<stdin>:3:2: note: scanning from here
  bla3
  ^
...

I expect the match to succeed, because I expect leading and trailing 
whitespace _not_ to be ignored, because the documentation states:
...
  --match-full-lines

     By default, FileCheck allows matches of anywhere on a line. This 
option will require all positive matches to cover an entire line. 
Leading and trailing whitespace is ignored, unless --strict-whitespace 
is also specified.
...

After adding some debug code to FileCheck (which I proposed here on 
llvm-dev ml as '[FileCheck] Add --verbose'), we can see where things go 
wrong:
...
$ cat DUMP | /home/vries/gt/build/./bin/FileCheck CHECK 
--strict-whitespace --match-full-lines --verbose
CHECK:3:16: note: RegEx string match: '^bla3$'
// CHECK-NEXT: bla3
...

The resulting regexp string is '^bla3$' instead of '^ bla3$'.

The patch fixes this, and makes the behavior match the documentation.

I ran the llvm/test/FileCheck tests, no regressions.

Any comments? OK for trunk?

Thanks,
- Tom
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