[clang] [clang][ssaf] Integrate source-edit-generation (PR #208590)

[Ziqing Luo via cfe-commits]

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+==============================
+Source Edit Generation
+==============================
+
+Source edit generation relies on a ``WPASuite`` result produced by an
+earlier whole-program analysis. It runs alongside the normal compile
+and emits two per-translation-unit artifacts:
+
+- a *source-edit file* (``--ssaf-src-edit-file=``) containing
+  ``clang::tooling::Replacement`` records ready for
+  ``clang-apply-replacements``,
+- a *transformation-report file* (``--ssaf-transformation-report-file=``)
+  containing diagnostic-style findings.
+
+Driver flags
+============
+
+Four flags control the pipeline; they are all both ``--ssaf-…`` driver
+flags and ``cc1`` flags. The compilation-unit identifier is shared
+with the summary extraction step. A given compilation unit needs to
+receive the same identifier for both summary extraction and source
+edit generation.
+
+.. list-table::
+   :header-rows: 1
+
+   * - Flag
+     - Purpose
+   * - ``--ssaf-source-transformation=<name>``
+     - Name of the transformation to run.
+   * - ``--ssaf-global-scope-analysis-result=<path>.<format>``
+     - WPASuite input. The extension selects the serialization format.
+   * - ``--ssaf-src-edit-file=<path>``
----------------
ziqingluo-90 wrote:

A possible follow-up SSAF discussion:  Can we make input/output explicit in flag names?  Like, adding "output" to all output flags `--ssaf-output-*`.

https://github.com/llvm/llvm-project/pull/208590