[lit] Make internal diff work in pipelines

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 file -
 # RUN: not diff file1 file2 | FileCheck %s
```

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` cannot
currently be used in pipelines and doesn't recognize `-` as a
command-line option.

To enable pipelines, this patch moves lit's `diff` implementation into
an out-of-process script, similar to lit's `cat` implementation.  A
follow-up patch will implement `-` to mean stdin.

Reviewed By: probinson, stella.stamenova

Differential Revision: https://reviews.llvm.org/D66574

llvm-svn: 375114

1 files changed, 45 insertions, 33 deletions

diff --git a/llvm/utils/lit/tests/shtest-shell.py b/llvm/utils/lit/tests/shtest-shell.py
index 1fc8b30..dd5bfbe 100644
--- a/llvm/utils/lit/tests/shtest-shell.py
+++ b/llvm/utils/lit/tests/shtest-shell.py
@@ -86,28 +86,20 @@
 # CHECK: ***
 
 
-# CHECK: FAIL: shtest-shell :: diff-error-0.txt
-# CHECK: *** TEST 'shtest-shell :: diff-error-0.txt' FAILED ***
-# CHECK: $ "diff" "diff-error-0.txt" "diff-error-0.txt"
-# CHECK: # command stderr:
-# CHECK: Unsupported: 'diff' cannot be part of a pipeline
-# CHECK: error: command failed with exit status: 127
-# CHECK: ***
-
 # CHECK: FAIL: shtest-shell :: diff-error-1.txt
 # CHECK: *** TEST 'shtest-shell :: diff-error-1.txt' FAILED ***
 # CHECK: $ "diff" "-B" "temp1.txt" "temp2.txt"
 # CHECK: # command stderr:
 # CHECK: Unsupported: 'diff': option -B not recognized
-# CHECK: error: command failed with exit status: 127
+# CHECK: error: command failed with exit status: 1
 # CHECK: ***
 
 # CHECK: FAIL: shtest-shell :: diff-error-2.txt
 # CHECK: *** TEST 'shtest-shell :: diff-error-2.txt' FAILED ***
 # CHECK: $ "diff" "temp.txt"
 # CHECK: # command stderr:
-# CHECK: Error:  missing or extra operand
-# CHECK: error: command failed with exit status: 127
+# CHECK: Error: missing or extra operand
+# CHECK: error: command failed with exit status: 1
 # CHECK: ***
 
 # CHECK: FAIL: shtest-shell :: diff-error-3.txt
@@ -134,18 +126,43 @@
 # CHECK: *** TEST 'shtest-shell :: diff-error-5.txt' FAILED ***
 # CHECK: $ "diff"
 # CHECK: # command stderr:
-# CHECK: Error:  missing or extra operand
-# CHECK: error: command failed with exit status: 127
+# CHECK: Error: missing or extra operand
+# CHECK: error: command failed with exit status: 1
 # CHECK: ***
 
 # CHECK: FAIL: shtest-shell :: diff-error-6.txt
 # CHECK: *** TEST 'shtest-shell :: diff-error-6.txt' FAILED ***
 # CHECK: $ "diff"
 # CHECK: # command stderr:
-# CHECK: Error:  missing or extra operand
-# CHECK: error: command failed with exit status: 127
+# CHECK: Error: missing or extra operand
+# CHECK: error: command failed with exit status: 1
+# CHECK: ***
+
+
+# CHECK: FAIL: shtest-shell :: diff-pipes.txt
+
+# CHECK: *** TEST 'shtest-shell :: diff-pipes.txt' FAILED ***
+
+# CHECK: $ "diff" "{{[^"]*}}.foo" "{{[^"]*}}.foo"
+# CHECK-NOT: note
+# CHECK-NOT: error
+# CHECK: $ "FileCheck"
+# CHECK-NOT: note
+# CHECK-NOT: error
+
+# CHECK: $ "diff" "-u" "{{[^"]*}}.foo" "{{[^"]*}}.bar"
+# CHECK: note: command had no output on stdout or stderr
+# CHECK: error: command failed with exit status: 1
+# CHECK: $ "FileCheck"
+# CHECK-NOT: note
+# CHECK-NOT: error
+# CHECK: $ "true"
+
+# CHECK: $ "false"
+
 # CHECK: ***
 
+
 # CHECK: FAIL: shtest-shell :: diff-r-error-0.txt
 # CHECK: *** TEST 'shtest-shell :: diff-r-error-0.txt' FAILED ***
 # CHECK: $ "diff" "-r" 
@@ -255,23 +272,6 @@
 # CHECK: ***
 
 
-# CHECK: FAIL: shtest-shell :: diff-unified-error-0.txt
-# CHECK: *** TEST 'shtest-shell :: diff-unified-error-0.txt' FAILED ***
-# CHECK: $ "diff" "-U" "30.1" "{{[^"]*}}" "{{[^"]*}}"
-# CHECK: # command stderr:
-# CHECK: Error: invalid '-U' argument: 30.1
-# CHECK: error: command failed with exit status: 127
-# CHECK: ***
-
-# CHECK: FAIL: shtest-shell :: diff-unified-error-1.txt
-# CHECK: *** TEST 'shtest-shell :: diff-unified-error-1.txt' FAILED ***
-# CHECK: $ "diff" "-U-1" "{{[^"]*}}" "{{[^"]*}}"
-# CHECK: # command stderr:
-# CHECK: Error: invalid '-U' argument: -1
-# CHECK: error: command failed with exit status: 127
-# CHECK: ***
-
-
 # CHECK: FAIL: shtest-shell :: diff-unified.txt
 
 # CHECK: *** TEST 'shtest-shell :: diff-unified.txt' FAILED ***
@@ -330,6 +330,18 @@
 # 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: ***
@@ -414,4 +426,4 @@
 # CHECK: PASS: shtest-shell :: sequencing-0.txt
 # CHECK: XFAIL: shtest-shell :: sequencing-1.txt
 # CHECK: PASS: shtest-shell :: valid-shell.txt
-# CHECK: Failing Tests (32)
+# CHECK: Failing Tests (30)