BUG: #57954 encoding ignored for filelike

pandas/io/parsers/readers.py

@@ -1485,6 +1485,17 @@ def _make_engine(
             "pyarrow": ArrowParserWrapper,
             "python-fwf": FixedWidthFieldParser,
         }
+
+        file_encoding = getattr(f, "encoding", None)
+        orig_reader_enc = self.orig_options.get("encoding", None)
+        are_both_encodings = file_encoding is not None and orig_reader_enc is not None
+        if are_both_encodings and file_encoding != orig_reader_enc:
+            file_path = getattr(f, "name", None)
+            raise ValueError(
+                f"The specified reader encoding {orig_reader_enc} is different from "
+                f"the encoding {file_encoding} of file {file_path}."
+            )
+
         if engine not in mapping:
             raise ValueError(
                 f"Unknown engine: {engine} (valid options are {mapping.keys()})"

pandas/tests/io/parser/test_c_parser_only.py

@@ -511,7 +511,7 @@ def __next__(self):
 def test_buffer_rd_bytes_bad_unicode(c_parser_only):
     # see gh-22748
     t = BytesIO(b"\xb0")
-    t = TextIOWrapper(t, encoding="ascii", errors="surrogateescape")
+    t = TextIOWrapper(t, encoding="UTF-8", errors="surrogateescape")
     msg = "'utf-8' codec can't encode character"
     with pytest.raises(UnicodeError, match=msg):
         c_parser_only.read_csv(t, encoding="UTF-8")

pandas/tests/io/parser/test_textreader.py

@@ -48,6 +48,13 @@ def test_StringIO(self, csv_path):
         reader = TextReader(src, header=None)
         reader.read()
 
+    def test_encoding_mismatch_warning(self, csv_path):
+        # GH-57954
+        with open(csv_path, encoding="UTF-8") as f:
+            msg = "latin1 is different from the encoding"
+            with pytest.raises(ValueError, match=msg):
+                read_csv(f, encoding="latin1")
+
     def test_string_factorize(self):
         # should this be optional?
         data = "a\nb\na\nb\na"