fix: prevent infinite recursion

If using relative file paths, and a file remapping failed, we'd get an
infinite recursion.

1 files changed, 8 insertions, 3 deletions

diff --git a/coverage/files.py b/coverage/files.py
index 14d696b6..63e9afb2 100644
--- a/coverage/files.py
+++ b/coverage/files.py
@@ -452,15 +452,20 @@ class PathAliases:
         # If we get here, no pattern matched.
 
         if self.relative and not isabs_anywhere(path):
+            # Auto-generate a pattern to implicitly match relative files
             parts = re.split(r"[/\\]", path)
             if len(parts) > 1:
                 dir1 = parts[0]
                 pattern = f"*/{dir1}"
                 regex = rf"^(.*[\\/])?{re.escape(dir1)}[\\/]"
                 result = f"{dir1}{os.sep}"
-                self.debugfn(f"Generating rule: {pattern!r} -> {result!r} using regex {regex!r}")
-                self.aliases.append((pattern, re.compile(regex), result))
-                return self.map(path, exists=exists)
+                # Only add a new pattern if we don't already have this pattern.
+                if not any(p == pattern for p, _, _ in self.aliases):
+                    self.debugfn(
+                        f"Generating rule: {pattern!r} -> {result!r} using regex {regex!r}"
+                    )
+                    self.aliases.append((pattern, re.compile(regex), result))
+                    return self.map(path, exists=exists)
 
         self.debugfn(f"No rules match, path {path!r} is unchanged")
         return path