Bugfix: ST02 - Compare entire condition expression (#5850)

sqlfluff · May 6, 2024 · 99b09d4 · 99b09d4
1 parent 49d48a5
commit 99b09d4
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Showing 2 changed files with 30 additions and 2 deletions.
diff --git a/src/sqlfluff/rules/structure/ST02.py b/src/sqlfluff/rules/structure/ST02.py
@@ -194,25 +194,40 @@ def _eval(self, context: RuleContext) -> Optional[LintResult]:
                     .children(sp.is_type("column_reference"))
                     .get()
                 )
+                array_accessor_segment = (
+                    Segments(condition_expression)
+                    .children(sp.is_type("array_accessor"))
+                    .get()
+                )
 
                 # Return None if none found (this condition does not apply to functions)
                 if not column_reference_segment:
                     return None
 
+                if array_accessor_segment:
+                    column_reference_segment_raw_upper = (
+                        column_reference_segment.raw_upper
+                        + array_accessor_segment.raw_upper
+                    )
+                else:
+                    column_reference_segment_raw_upper = (
+                        column_reference_segment.raw_upper
+                    )
+
                 if else_clauses:
                     else_expression = else_clauses.children(sp.is_type("expression"))[0]
                     # Check if we can reduce the CASE expression to a single coalesce
                     # function.
                     if (
                         not is_not_prefix
-                        and column_reference_segment.raw_upper
+                        and column_reference_segment_raw_upper
                         == else_expression.raw_upper
                     ):
                         coalesce_arg_1 = else_expression
                         coalesce_arg_2 = then_expression
                     elif (
                         is_not_prefix
-                        and column_reference_segment.raw_upper
+                        and column_reference_segment_raw_upper
                         == then_expression.raw_upper
                     ):
                         coalesce_arg_1 = then_expression

diff --git a/test/fixtures/rules/std_rule_cases/ST02.yml b/test/fixtures/rules/std_rule_cases/ST02.yml
@@ -107,6 +107,19 @@ test_pass_case_cannot_be_reduced_13:
   configs:
     core:
       dialect: postgres
+test_pass_array_accessors:
+  pass_str: |
+    SELECT
+    CASE
+        WHEN genres[0] IS NULL
+           THEN 'x'
+        ELSE genres
+    END
+    AS g
+    FROM table_t
+  configs:
+    core:
+      dialect: snowflake
 test_fail_unnecessary_case_1:
   fail_str: |
     select