Add handling for Redshift CONVERT function data type argument

src/sqlfluff/dialects/dialect_redshift.py

@@ -2308,3 +2308,76 @@ class SelectClauseModifierSegment(postgres.SelectClauseModifierSegment):
     match_grammar = postgres.SelectClauseModifierSegment.match_grammar.copy(
         insert=[Sequence("TOP", Ref("NumericLiteralSegment"))],
     )
+
+
+class ConvertFunctionNameSegment(BaseSegment):
+    """CONVERT function name segment.
+
+    Function taking a data type identifier and an expression.
+    An alternative to CAST.
+    """
+
+    type = "function_name"
+    match_grammar = Sequence("CONVERT")
+
+
+class FunctionSegment(ansi.FunctionSegment):
+    """A scalar or aggregate function.
+
+    Maybe in the future we should distinguish between
+    aggregate functions and other functions. For now
+    we treat them the same because they look the same
+    for our purposes.
+    """
+
+    type = "function"
+    match_grammar: Matchable = OneOf(
+        Sequence(
+            # Treat functions which take date parts separately
+            # So those functions parse date parts as DatetimeUnitSegment
+            # rather than identifiers.
+            Sequence(
+                Ref("DatePartFunctionNameSegment"),
+                Bracketed(
+                    Delimited(
+                        Ref("DatetimeUnitSegment"),
+                        Ref(
+                            "FunctionContentsGrammar",
+                            # The brackets might be empty for some functions...
+                            optional=True,
+                            ephemeral_name="FunctionContentsGrammar",
+                        ),
+                    )
+                ),
+            ),
+        ),
+        Sequence(
+            Sequence(
+                Ref(
+                    "FunctionNameSegment",
+                    exclude=OneOf(
+                        Ref("DatePartFunctionNameSegment"),
+                        Ref("ValuesClauseSegment"),
+                        Ref("ConvertFunctionNameSegment"),
+                    ),
+                ),
+                Bracketed(
+                    Ref(
+                        "FunctionContentsGrammar",
+                        # The brackets might be empty for some functions...
+                        optional=True,
+                        ephemeral_name="FunctionContentsGrammar",
+                    )
+                ),
+            ),
+            Ref("PostFunctionGrammar", optional=True),
+        ),
+        Sequence(
+            Ref("ConvertFunctionNameSegment"),
+            Bracketed(
+                Ref("DatatypeSegment"),
+                Ref("CommaSegment"),
+                Ref("ExpressionSegment"),
+            ),
+        ),
+    )

test/fixtures/dialects/redshift/redshift_cast_conversion.yml

@@ -3,7 +3,7 @@
 # computed by SQLFluff when running the tests. Please run
 # `python test/generate_parse_fixture_yml.py`  to generate them after adding or
 # altering SQL files.
-_hash: d88e5f09aebf827225e0e8212e0629860009f8d5ac1bdb6f8df8abbd37bcbda4
+_hash: 29b2bd2f7511b32a80bbd5d7ef8cfdc99ef123a566c1f35099f3d97b439675da
 file:
 - statement:
     select_statement:
@@ -37,17 +37,16 @@ file:
         select_clause_element:
           function:
             function_name:
-              function_name_identifier: convert
+              keyword: convert
             bracketed:
-            - start_bracket: (
-            - expression:
-                column_reference:
-                  identifier: integer
-            - comma: ','
-            - expression:
+              start_bracket: (
+              data_type:
+                keyword: integer
+              comma: ','
+              expression:
                 column_reference:
                   identifier: col1
-            - end_bracket: )
+              end_bracket: )
       from_clause:
         keyword: from
         from_expression:
@@ -109,17 +108,17 @@ file:
         select_clause_element:
           function:
             function_name:
-              function_name_identifier: convert
+              keyword: convert
             bracketed:
-            - start_bracket: (
-            - expression:
-                column_reference:
-                  identifier: timestamptz
-            - comma: ','
-            - expression:
+              start_bracket: (
+              data_type:
+                datetime_type_identifier:
+                  keyword: timestamptz
+              comma: ','
+              expression:
                 column_reference:
                   identifier: col1
-            - end_bracket: )
+              end_bracket: )
       from_clause:
         keyword: from
         from_expression:
@@ -187,26 +186,22 @@ file:
         select_clause_element:
           function:
             function_name:
-              function_name_identifier: convert
+              keyword: convert
             bracketed:
-            - start_bracket: (
-            - expression:
-                function:
-                  function_name:
-                    function_name_identifier: decimal
-                  bracketed:
-                  - start_bracket: (
-                  - expression:
-                      literal: '38'
-                  - comma: ','
-                  - expression:
-                      literal: '2'
-                  - end_bracket: )
-            - comma: ','
-            - expression:
+              start_bracket: (
+              data_type:
+                keyword: decimal
+                bracketed:
+                - start_bracket: (
+                - literal: '38'
+                - comma: ','
+                - literal: '2'
+                - end_bracket: )
+              comma: ','
+              expression:
                 column_reference:
                   identifier: col1
-            - end_bracket: )
+              end_bracket: )
       from_clause:
         keyword: from
         from_expression:
@@ -273,17 +268,16 @@ file:
         select_clause_element:
           function:
             function_name:
-              function_name_identifier: convert
+              keyword: convert
             bracketed:
-            - start_bracket: (
-            - expression:
-                column_reference:
-                  identifier: interval
-            - comma: ','
-            - expression:
+              start_bracket: (
+              data_type:
+                keyword: interval
+              comma: ','
+              expression:
                 column_reference:
                   identifier: col1
-            - end_bracket: )
+              end_bracket: )
       from_clause:
         keyword: from
         from_expression:

test/fixtures/rules/std_rule_cases/L027.yml

@@ -336,3 +336,16 @@ test_pass_ansi:
         INNER JOIN mapping_table ON (mapping_table.other_fk = other_table.id_pk)
         WHERE mapping_table.kind = my_table.kind
     )
+
+test_pass_redshift_convert:
+  # This was failing in issue 3651.
+  pass_str: |
+    SELECT
+        sellers.name,
+        CONVERT(integer, sales.pricepaid) AS price
+    FROM sales
+    LEFT JOIN sellers ON sales.sellerid = sellers.sellerid
+    WHERE sales.salesid = 100
+  configs:
+    core:
+      dialect: redshift