[llvm] lit: Move RUN at line comment after the command. (PR #132485)

[Peter Collingbourne via llvm-commits]

https://github.com/pcc created https://github.com/llvm/llvm-project/pull/132485

When a developer copy/pastes a failing command line into their
shell to rerun it, they have to manually delete the "RUN: at line
N:" prefix. To make life easier for such developers, let's make it
possible to copy/paste a command without needing to modify it while
still showing the line number in the output by moving the line number
to a comment at the end of the command line.


>From 712c6229e1c1e28ce44ffcfda643c59d55c24200 Mon Sep 17 00:00:00 2001
From: Peter Collingbourne <pcc at google.com>
Date: Fri, 21 Mar 2025 16:05:00 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.6-beta.1
---
 llvm/docs/CommandGuide/lit.rst   | 2 +-
 llvm/utils/lit/lit/TestRunner.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/llvm/docs/CommandGuide/lit.rst b/llvm/docs/CommandGuide/lit.rst
index 8c0e275e1f8ca..812e1d819e9c8 100644
--- a/llvm/docs/CommandGuide/lit.rst
+++ b/llvm/docs/CommandGuide/lit.rst
@@ -100,7 +100,7 @@ OUTPUT OPTIONS
 
  Each command is printed before it is executed. This can be valuable for
  debugging test failures, as the last printed command is the one that failed.
- Moreover, :program:`lit` inserts ``'RUN: at line N'`` before each
+ Moreover, :program:`lit` inserts ``'RUN: at line N'`` after each
  command pipeline in the output to help you locate the source line of
  the failed command.
 
diff --git a/llvm/utils/lit/lit/TestRunner.py b/llvm/utils/lit/lit/TestRunner.py
index 00432b8d31778..dab83cbc20624 100644
--- a/llvm/utils/lit/lit/TestRunner.py
+++ b/llvm/utils/lit/lit/TestRunner.py
@@ -1231,7 +1231,7 @@ def executeScript(test, litConfig, tmpBase, commands, cwd):
                 # the shell's execution trace for the 'set' commands by
                 # redirecting their stderr to /dev/null.
                 if command:
-                    msg = f"'{dbg}': {shlex.quote(command.lstrip())}"
+                    msg = f"{shlex.quote(command.lstrip())} \\# '{dbg}'"
                 else:
                     msg = f"'{dbg}' has no command after substitutions"
                 commands[i] = (