Reapply "lit: Move RUN at line comment after the command."

This reverts commit 57e89c9.

Updated lit tests.

Author: pcc

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.
 

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] = (

llvm/utils/lit/tests/shtest-external-shell-kill.py

@@ -31,6 +31,6 @@
 #  CHECK-NEXT: --
 #  CHECK-NEXT: Command Output (stderr):
 #  CHECK-NEXT: --
-#  CHECK-NEXT: RUN: at line 1: echo start
+#  CHECK-NEXT: echo start # RUN: at line 1 
 #  CHECK-NEXT: echo start
-#  CHECK-NEXT: RUN: at line 2: sleep [[#]] & PID=$!
+#  CHECK-NEXT: sleep [[#]] & PID=$! # RUN: at line 2

llvm/utils/lit/tests/shtest-run-at-line.py

@@ -17,9 +17,9 @@
 
 #       CHECK: Command Output (stderr)
 #  CHECK-NEXT: --
-#  CHECK-NEXT: {{^}}RUN: at line 4: true{{$}}
+#  CHECK-NEXT: {{^}}true # RUN: at line 4{{$}}
 #  CHECK-NEXT: true
-#  CHECK-NEXT: {{^}}RUN: at line 5: false{{$}}
+#  CHECK-NEXT: {{^}}false # RUN: at line 5{{$}}
 #  CHECK-NEXT: false
 # CHECK-EMPTY:
 #  CHECK-NEXT: --
@@ -29,7 +29,7 @@
 #       CHECK: Command Output (stderr)
 #  CHECK-NEXT: --
 #  CHECK-NEXT: {{^}}RUN: at line 2 has no command after substitutions{{$}}
-#  CHECK-NEXT: {{^}}RUN: at line 3: false{{$}}
+#  CHECK-NEXT: {{^}}false # RUN: at line 3{{$}}
 #  CHECK-NEXT: false
 # CHECK-EMPTY:
 #  CHECK-NEXT: --
@@ -42,19 +42,19 @@
 
 #       CHECK: Command Output (stderr)
 #  CHECK-NEXT: --
-#  CHECK-NEXT: {{^}}RUN: at line 4: echo 'foo bar' | FileCheck
+#  CHECK-NEXT: {{^}}echo 'foo bar' | FileCheck {{.*}} # RUN: at line 4 
 #   CHECK-NOT: RUN
-#       CHECK: {{^}}RUN: at line 6: echo 'foo baz' | FileCheck
+#       CHECK: {{^}}echo 'foo baz' | FileCheck {{.*}} # RUN: at line 6 
 #   CHECK-NOT: RUN
 #       CHECK: --
 
 # CHECK-LABEL: FAIL: shtest-run-at-line :: external-shell/run-line-with-newline.txt
 
 #      CHECK: Command Output (stderr)
 # CHECK-NEXT: --
-# CHECK-NEXT: {{^}}RUN: at line 1: echo abc |
+# CHECK-NEXT: {{^}}echo abc |
 # CHECK-NEXT: FileCheck {{.*}} &&
-# CHECK-NEXT: false
+# CHECK-NEXT: false # RUN: at line 1
 #  CHECK-NOT: RUN