[lit] Extend internal diff to support -U

When using lit's internal shell, RUN lines like the following
accidentally execute an external `diff` instead of lit's internal
`diff`:

```
 # RUN: program | diff -U1 file -
```

Such cases exist now, in `clang/test/Analysis` for example.  We are
preparing patches to ensure lit's internal `diff` is called in such
cases, which will then fail because lit's internal `diff` doesn't
recognize `-U` as a command-line option.  This patch adds `-U`
support.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D68668

llvm-svn: 374392

1 files changed, 77 insertions, 1 deletions

diff --git a/llvm/utils/lit/tests/shtest-shell.py b/llvm/utils/lit/tests/shtest-shell.py
index db57c3af1f1..c7e05d6bc42 100644
--- a/llvm/utils/lit/tests/shtest-shell.py
+++ b/llvm/utils/lit/tests/shtest-shell.py
@@ -331,6 +331,82 @@
 
 # CHECK: PASS: shtest-shell :: diff-r.txt
 
+
+# CHECK: FAIL: shtest-shell :: diff-unified.txt
+
+# CHECK: *** TEST 'shtest-shell :: diff-unified.txt' FAILED ***
+
+# CHECK: $ "diff" "-u" "{{[^"]*}}.foo" "{{[^"]*}}.bar"
+# CHECK: # command output:
+# CHECK: @@ {{.*}} @@
+# CHECK-NEXT: 3
+# CHECK-NEXT: 4
+# CHECK-NEXT: 5
+# CHECK-NEXT: -6 foo
+# CHECK-NEXT: +6 bar
+# CHECK-NEXT: 7
+# CHECK-NEXT: 8
+# CHECK-NEXT: 9
+# CHECK-EMPTY:
+# CHECK-NEXT: error: command failed with exit status: 1
+# CHECK-NEXT: $ "true"
+
+# CHECK: $ "diff" "-U" "2" "{{[^"]*}}.foo" "{{[^"]*}}.bar"
+# CHECK: # command output:
+# CHECK: @@ {{.*}} @@
+# CHECK-NEXT: 4
+# CHECK-NEXT: 5
+# CHECK-NEXT: -6 foo
+# CHECK-NEXT: +6 bar
+# CHECK-NEXT: 7
+# CHECK-NEXT: 8
+# CHECK-EMPTY:
+# CHECK-NEXT: error: command failed with exit status: 1
+# CHECK-NEXT: $ "true"
+
+# CHECK: $ "diff" "-U4" "{{[^"]*}}.foo" "{{[^"]*}}.bar"
+# CHECK: # command output:
+# CHECK: @@ {{.*}} @@
+# CHECK-NEXT: 2
+# CHECK-NEXT: 3
+# CHECK-NEXT: 4
+# CHECK-NEXT: 5
+# CHECK-NEXT: -6 foo
+# CHECK-NEXT: +6 bar
+# CHECK-NEXT: 7
+# CHECK-NEXT: 8
+# CHECK-NEXT: 9
+# CHECK-NEXT: 10
+# CHECK-EMPTY:
+# CHECK-NEXT: error: command failed with exit status: 1
+# CHECK-NEXT: $ "true"
+
+# CHECK: $ "diff" "-U0" "{{[^"]*}}.foo" "{{[^"]*}}.bar"
+# CHECK: # command output:
+# CHECK: @@ {{.*}} @@
+# CHECK-NEXT: -6 foo
+# CHECK-NEXT: +6 bar
+# CHECK-EMPTY:
+# CHECK-NEXT: error: command failed with exit status: 1
+# CHECK-NEXT: $ "true"
+
+# CHECK: $ "diff" "-U" "30.1" "{{[^"]*}}" "{{[^"]*}}"
+# CHECK: # command stderr:
+# CHECK: Error: invalid '-U' argument: 30.1
+# CHECK: error: command failed with exit status: 1
+# CHECK: $ "true"
+
+# CHECK: $ "diff" "-U-1" "{{[^"]*}}" "{{[^"]*}}"
+# CHECK: # command stderr:
+# CHECK: Error: invalid '-U' argument: -1
+# CHECK: error: command failed with exit status: 1
+# CHECK: $ "true"
+
+# CHECK: $ "false"
+
+# CHECK: ***
+
+
 # CHECK: FAIL: shtest-shell :: error-0.txt
 # CHECK: *** TEST 'shtest-shell :: error-0.txt' FAILED ***
 # CHECK: $ "not-a-real-command"
@@ -410,4 +486,4 @@
 # CHECK: PASS: shtest-shell :: sequencing-0.txt
 # CHECK: XFAIL: shtest-shell :: sequencing-1.txt
 # CHECK: PASS: shtest-shell :: valid-shell.txt
-# CHECK: Failing Tests (30)
+# CHECK: Failing Tests (31)