Fixes #4265.

changelog.md

@@ -257,6 +257,8 @@ bar()
 - The ``securehash`` module is now deprecated. Instead import ``std / sha1``.
 - ``db_mysql`` module: ``DbConn`` is now a ``distinct`` type that doesn't expose the
   details of the underlying ``PMySQL`` type.
+- ``strtabs.getOrDefault`` now returns ``nil`` instead of ``""``. See
+  [#4265](https://github.com/nim-lang/Nim/issues/4265) for more info.
 - Standard library modules can now also be imported via the ``std`` pseudo-directory.
   This is useful in order to distinguish between standard library and nimble package
   imports:

lib/pure/strtabs.nim

@@ -129,7 +129,7 @@ proc mget*(t: StringTableRef, key: string): var string {.deprecated.} =
   ## ``KeyError`` exception is raised. Use ```[]``` instead.
   get(t, key)
 
-proc getOrDefault*(t: StringTableRef; key: string, default: string = ""): string =
+proc getOrDefault*(t: StringTableRef; key: string, default: string = nil): string =
   var index = rawGet(t, key)
   if index >= 0: result = t.data[index].val
   else: result = default