[clang] [llvm] Reland "[Utils] Add new --update-tests flag to llvm-lit" (PR #153821)

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github-actions[bot] wrote:

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``````````bash
darker --check --diff -r HEAD~1...HEAD llvm/utils/lit/lit/DiffUpdater.py llvm/utils/lit/tests/diff-test-update.py clang/test/lit.cfg.py llvm/test/lit.cfg.py llvm/utils/lit/lit/LitConfig.py llvm/utils/lit/lit/TestRunner.py llvm/utils/lit/lit/cl_arguments.py llvm/utils/lit/lit/llvm/config.py llvm/utils/lit/lit/main.py llvm/utils/update_any_test_checks.py
``````````

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View the diff from darker here.
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``````````diff
--- llvm/utils/lit/lit/DiffUpdater.py	2025-08-15 15:32:42.000000 +0000
+++ llvm/utils/lit/lit/DiffUpdater.py	2025-08-15 15:38:18.640968 +0000
@@ -1,6 +1,7 @@
 import shutil
+
 
 def get_source_and_target(a, b):
     """
     Try to figure out which file is the test output and which is the reference.
     """
@@ -16,12 +17,14 @@
     if tmp_substr in b and not tmp_substr in a:
         return b, a
 
     return None
 
+
 def filter_flags(args):
     return [arg for arg in args if not arg.startswith("-")]
+
 
 def diff_test_updater(result, test):
     args = filter_flags(result.command.args)
     if len(args) != 3:
         return None

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https://github.com/llvm/llvm-project/pull/153821