feat(snowflake)!: Transpilation support for TO_DECIMAL, TO_NUMBER, TO_NUMERIC . 3.9 support. string concatenation ("\\" + c) instead of f-string interpolation

Author: fivetran-ashashankar

sqlglot/dialects/duckdb.py

@@ -4213,11 +4213,13 @@ def tonumber_sql(self, expression: exp.ToNumber) -> str:
                 chars = [c for symbol, c in chars_to_remove.items() if symbol in format_string]
 
                 if chars:
-                    pattern = (
-                        chars[0]
-                        if len(chars) == 1
-                        else f"[{''.join(c if c not in '.^$*+?{}[]\\|()' else f'\\{c}' for c in chars)}]"
-                    )
+                    if len(chars) == 1:
+                        pattern = chars[0]
+                    else:
+                        # Escape special regex characters (Python 3.9 compatible)
+                        regex_special = r".^$*+?{}[]\|()"
+                        escaped = [c if c not in regex_special else "\\" + c for c in chars]
+                        pattern = "[" + "".join(escaped) + "]"
                     this = exp.RegexpReplace(
                         this=this,
                         expression=exp.Literal.string(pattern),