[lit] Report line number for failed RUN command

When debugging test failures with -vv (or -v in the case of the
internal shell), this makes it easier to locate the RUN line that
failed.  For example, clang's test/Driver/linux-ld.c has 892 total RUN
lines, and clang's test/Driver/arm-cortex-cpus.c has 424 RUN lines
after concatenation for line continuations.

When reading the generated shell script, this also makes it easier to
locate the RUN line that produced each command.

To support reporting RUN line numbers in the case of the internal
shell, this patch extends the internal shell to support the null
command, ":", except pipelines are not supported.

Reviewed By: asmith, delcypher

Differential Revision: https://reviews.llvm.org/D44598

llvm-svn: 330755

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/docs/CommandGuide/lit.rst b/llvm/docs/CommandGuide/lit.rst
index fbe1a9ab184..11337696eb5 100644
--- a/llvm/docs/CommandGuide/lit.rst
+++ b/llvm/docs/CommandGuide/lit.rst
@@ -85,6 +85,8 @@ OUTPUT OPTIONS
  Echo all commands to stdout, as they are being executed.
  This can be valuable for debugging test failures, as the last echoed command
  will be the one which has failed.
+ To help you find the source RUN line, :program:`lit` inserts a no-op ``:``
+ command with argument ``'RUN: at line N'`` before each command pipeline.
  This option implies ``--verbose``.
 
 .. option:: -a, --show-all