should be it

external/duckdb/benchmark/micro/cast/cast_varcharstruct_string.benchmark

@@ -0,0 +1,22 @@
+# name: benchmark/micro/cast/cast_varcharstruct_string.benchmark
+# description: Cast struct values with varchar fields to string
+# group: [cast]
+
+name Cast STRUCT<VARCHAR> -> VARCHAR
+group cast
+
+load
+CREATE TABLE structs AS SELECT {
+    'simple': 'red',
+    'needs_space': '  leading space  ',
+    'null_field': NULL,
+    'null_text': 'null',
+    'special:char': 'value:with:colons',
+    'quoted''field': 'text with ''quotes'''
+} s FROM range(0, 10000000) tbl(i);
+
+run
+SELECT MIN(CAST(s AS VARCHAR)) FROM structs;
+
+result I
+{'simple': red, 'needs_space': '  leading space  ', 'null_field': NULL, 'null_text': 'null', 'special:char': 'value:with:colons', 'quoted\'field': 'text with \'quotes\''}