[clang] [llvm] [Utils] Adds support for diff based tests to lit's --update-tests (PR #154147)

[via llvm-commits]

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	2025-08-18 16:43:09.000000 +0000
+++ llvm/utils/lit/lit/DiffUpdater.py	2025-08-18 16:47:57.066277 +0000
@@ -13,10 +13,11 @@
     - Support stdin patterns like "my_binary %s | diff expected.txt"
     - Scan RUN lines to see if a file is the source of output from a previous command.
       If it is then it is not a reference file that can be copied to, regardless of name, since the test will overwrite it anyways.
     - Only update the parts that need updating (based on the diff output). Could help avoid noisy updates when e.g. whitespace changes are ignored.
 """
+
 
 def get_source_and_target(a, b):
     """
     Try to figure out which file is the test output and which is the reference.
     """

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https://github.com/llvm/llvm-project/pull/154147