Move conversion of PR diff-range paths to absolute paths

src/diff-informed-analysis-utils.ts

@@ -191,13 +191,6 @@ function getDiffRanges(
   fileDiff: FileDiff,
   logger: Logger,
 ): DiffThunkRange[] | undefined {
-  // Diff-informed queries expect the file path to be absolute. CodeQL always
-  // uses forward slashes as the path separator, so on Windows we need to
-  // replace any backslashes with forward slashes.
-  const filename = path
-    .join(actionsUtil.getRequiredInput("checkout_path"), fileDiff.filename)
-    .replaceAll(path.sep, "/");
-
   if (fileDiff.patch === undefined) {
     if (fileDiff.changes === 0) {
       // There are situations where a changed file legitimately has no diff.
@@ -212,7 +205,7 @@ function getDiffRanges(
     // to a special diff range that covers the entire file.
     return [
       {
-        path: filename,
+        path: fileDiff.filename,
         startLine: 0,
         endLine: 0,
       },
@@ -247,7 +240,7 @@ function getDiffRanges(
       // Any line that does not start with a "+" or "-" terminates the current
       // range of added lines.
       diffRanges.push({
-        path: filename,
+        path: fileDiff.filename,
         startLine: additionRangeStartLine,
         endLine: currentLine - 1,
       });