From 77bc2a595e0494042183906e259b153fdcc57556 Mon Sep 17 00:00:00 2001
From: Chuan-kai Lin <cklin@github.com>
Date: Fri, 14 Feb 2025 08:50:52 -0800
Subject: [PATCH] Write pr-diff-range JSON file

---
 src/analyze.ts              | 14 ++++++++------
 src/diff-filtering-utils.ts | 27 +++++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 6 deletions(-)
 create mode 100644 src/diff-filtering-utils.ts

diff --git a/src/analyze.ts b/src/analyze.ts
index d21418d42..a3508e545 100644
--- a/src/analyze.ts
+++ b/src/analyze.ts
@@ -12,6 +12,10 @@ import { setupCppAutobuild } from "./autobuild";
 import { CodeQL, getCodeQL } from "./codeql";
 import * as configUtils from "./config-utils";
 import { addDiagnostic, makeDiagnostic } from "./diagnostics";
+import {
+  DiffThunkRange,
+  writeDiffRangesJsonFile,
+} from "./diff-filtering-utils";
 import { EnvVar } from "./environment";
 import { FeatureEnablement, Feature } from "./feature-flags";
 import { isScannedLanguage, Language } from "./languages";
@@ -284,12 +288,6 @@ export async function setupDiffInformedQueryRun(
   );
 }
 
-interface DiffThunkRange {
-  path: string;
-  startLine: number;
-  endLine: number;
-}
-
 /**
  * Return the file line ranges that were added or modified in the pull request.
  *
@@ -537,6 +535,10 @@ extensions:
     `Wrote pr-diff-range extension pack to ${extensionFilePath}:\n${extensionContents}`,
   );
 
+  // Write the diff ranges to a JSON file, for action-side alert filtering by the
+  // upload-lib module.
+  writeDiffRangesJsonFile(logger, ranges);
+
   return diffRangeDir;
 }
 
diff --git a/src/diff-filtering-utils.ts b/src/diff-filtering-utils.ts
new file mode 100644
index 000000000..8cf9c1c8a
--- /dev/null
+++ b/src/diff-filtering-utils.ts
@@ -0,0 +1,27 @@
+import * as fs from "fs";
+import * as path from "path";
+
+import * as actionsUtil from "./actions-util";
+import { Logger } from "./logging";
+
+export interface DiffThunkRange {
+  path: string;
+  startLine: number;
+  endLine: number;
+}
+
+function getDiffRangesJsonFilePath(): string {
+  return path.join(actionsUtil.getTemporaryDirectory(), "pr-diff-range.json");
+}
+
+export function writeDiffRangesJsonFile(
+  logger: Logger,
+  ranges: DiffThunkRange[],
+): void {
+  const jsonContents = JSON.stringify(ranges, null, 2);
+  const jsonFilePath = getDiffRangesJsonFilePath();
+  fs.writeFileSync(jsonFilePath, jsonContents);
+  logger.debug(
+    `Wrote pr-diff-range JSON file to ${jsonFilePath}:\n${jsonContents}`,
+  );
+}