[lit] Fix internal diff's --strip-trailing-cr and use it

Using GNU diff, `--strip-trailing-cr` removes a `\r` appearing before
a `\n` at the end of a line.  Without this patch, lit's internal diff
only removes `\r` if it appears as the last character.  That seems
useless.  This patch fixes that.

This patch also adds `--strip-trailing-cr` to some tests that fail on
Windows bots when D68664 is applied.  Based on what I see in the bot
logs, I think the following is happening.  In each test there, lit
diff is comparing a file with `\r\n` line endings to a file with `\n`
line endings.  Without D68664, lit diff reads those files with
Python's universal newlines support activated, causing `\r` to be
dropped.  However, with D68664, lit diff reads the files in binary
mode instead and thus reports that every line is different, just as
GNU diff does (at least under Ubuntu).  Adding `--strip-trailing-cr`
to those tests restores the previous behavior while permitting the
behavior of lit diff to be more like GNU diff.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D68839

llvm-svn: 374652

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/utils/lit/tests/max-failures.py b/llvm/utils/lit/tests/max-failures.py
index 3b85ae18611..6ad37533692 100644
--- a/llvm/utils/lit/tests/max-failures.py
+++ b/llvm/utils/lit/tests/max-failures.py
@@ -8,7 +8,7 @@
 #
 # END.
 
-# CHECK: Failing Tests (31)
+# CHECK: Failing Tests (32)
 # CHECK: Failing Tests (1)
 # CHECK: Failing Tests (2)
 # CHECK: error: argument --max-failures: requires positive integer, but found '0'