# RUN: echo foo > %t.foo
# RUN: echo bar > %t.bar

# Check output pipe.
# RUN: diff %t.foo %t.foo | FileCheck -allow-empty -check-prefix=EMPTY %s
# RUN: diff -u %t.foo %t.bar | FileCheck %s && false || true

# Check input pipe.
# RUN: cat %t.foo | diff -u - %t.foo
# RUN: cat %t.foo | diff -u %t.foo -
# RUN: cat %t.bar | diff -u %t.foo - && false || true
# RUN: cat %t.bar | diff -u - %t.foo && false || true

# Check output and input pipes at the same time.
# RUN: cat %t.foo | diff - %t.foo | FileCheck -allow-empty -check-prefix=EMPTY %s
# RUN: cat %t.bar | diff -u %t.foo - | FileCheck %s && false || true

# Fail so lit will print output.
# RUN: false

# CHECK:      @@
# CHECK-NEXT: -foo
# CHECK-NEXT: +bar

# EMPTY-NOT: {{.}}