1 files changed, 50 insertions, 0 deletions
diff --git a/tests/run-make/coverage-reports/sort_subviews.py b/tests/run-make/coverage-reports/sort_subviews.py
new file mode 100644
index 00000000000..10cfc51d447
--- /dev/null
+++ b/tests/run-make/coverage-reports/sort_subviews.py
@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+
+# `llvm-cov show` prints grouped subviews (e.g. for generic functions) in an
+# unstable order, which is inconvenient when checking output snapshots with
+# `diff`. To work around that, this script detects consecutive subviews in its
+# piped input, and sorts them while preserving their contents.
+
+from __future__ import print_function
+
+import sys
+
+
+def main():
+    subviews = []
+
+    def flush_subviews():
+        if not subviews:
+            return
+
+        # The last "subview" should be just a boundary line on its own, so
+        # temporarily remove it before sorting the accumulated subviews.
+        terminator = subviews.pop()
+        subviews.sort()
+        subviews.append(terminator)
+
+        for view in subviews:
+            for line in view:
+                print(line, end="")
+
+        subviews.clear()
+
+    for line in sys.stdin:
+        if line.startswith("  ------------------"):
+            # This is a subview boundary line, so start a new subview.
+            subviews.append([line])
+        elif line.startswith("  |"):
+            # Add this line to the current subview.
+            subviews[-1].append(line)
+        else:
+            # This line is not part of a subview, so sort and print any
+            # accumulated subviews, and then print the line as-is.
+            flush_subviews()
+            print(line, end="")
+
+    flush_subviews()
+    assert not subviews
+
+
+if __name__ == "__main__":
+    main()