address @ggevay's buggy name regression

Author: mgree

src/expr/src/explain/text.rs

@@ -1192,10 +1192,11 @@ where
                 M::humanize_ident(*self.expr.0, ident, f)
             }
             // We don't have name inferred for this column.
-            _ => {
-                // Write the stored name.
-                write!(f, "#{}{{{}}}", self.expr.0, self.expr.1)
-            }
+            _ => M::humanize_ident(
+                *self.expr.0,
+                Ident::new_unchecked(self.expr.1.to_string()),
+                f,
+            ),
         }
     }
 }

src/transform/src/analysis.rs

@@ -959,12 +959,14 @@ mod column_names {
     }
 
     impl ColumnName {
-        /// Return `true` iff this the variant is not unknown.
+        /// Return `true` iff the variant has an inferred name.
         pub fn is_known(&self) -> bool {
-            matches!(
-                self,
-                Self::Global(..) | Self::Aggregate(..) | Self::Annotated(..)
-            )
+            match self {
+                Self::Global(..) | Self::Aggregate(..) => true,
+                // We treat annotated columns as unknown because we would rather
+                // override them with inferred names, if we can.
+                Self::Annotated(..) | Self::Unknown => false,
+            }
         }
 
         /// Humanize the column to a [`String`], returns an empty [`String`] for

test/sqllogictest/github-31878.slt

@@ -0,0 +1,103 @@
+# Copyright Materialize, Inc. and contributors. All rights reserved.
+#
+# Use of this software is governed by the Business Source License
+# included in the LICENSE file at the root of this repository.
+#
+# As of the Change Date specified in that file, in accordance with
+# the Business Source License, use of this software will be governed
+# by the Apache License, Version 2.0.
+
+mode cockroach
+
+statement ok
+create table t1(x int, y int);
+
+query T multiline
+EXPLAIN OPTIMIZED PLAN WITH (humanized expressions, column names) AS VERBOSE TEXT FOR
+select sum(x) + 5 as s from t1;
+----
+Explained Query:
+  With
+    cte l0 =
+      Reduce aggregates=[sum(#0{x})] // { column_names: "(sum_x)" }
+        Project (#0{x}) // { column_names: "(x)" }
+          ReadStorage materialize.public.t1 // { column_names: "(x, y)" }
+  Return // { column_names: "(#0)" }
+    Project (#1) // { column_names: "(#0)" }
+      Map ((#0{sum_x} + 5)) // { column_names: "(sum_x, #1)" }
+        Union // { column_names: "(sum_x)" }
+          Get l0 // { column_names: "(sum_x)" }
+          Map (null) // { column_names: "(#0)" }
+            Union // { column_names: "()" }
+              Negate // { column_names: "()" }
+                Project () // { column_names: "()" }
+                  Get l0 // { column_names: "(sum_x)" }
+              Constant // { column_names: "()" }
+                - ()
+
+Source materialize.public.t1
+
+Target cluster: quickstart
+
+EOF
+
+query T multiline
+EXPLAIN OPTIMIZED PLAN WITH (humanized expressions) AS VERBOSE TEXT FOR
+select sum(x) + 5 as s from t1;
+----
+Explained Query:
+  With
+    cte l0 =
+      Reduce aggregates=[sum(#0{x})]
+        Project (#0{x})
+          ReadStorage materialize.public.t1
+  Return
+    Project (#1)
+      Map ((#0{sum_x} + 5))
+        Union
+          Get l0
+          Map (null)
+            Union
+              Negate
+                Project ()
+                  Get l0
+              Constant
+                - ()
+
+Source materialize.public.t1
+
+Target cluster: quickstart
+
+EOF
+
+# NB no humanized expressions means we won't infer any column names
+# but we _will_ get to keep the annotated names (for better or worse)
+
+query T multiline
+EXPLAIN OPTIMIZED PLAN WITH (humanized expressions = false) AS VERBOSE TEXT FOR
+select sum(x) + 5 as s from t1;
+----
+Explained Query:
+  With
+    cte l0 =
+      Reduce aggregates=[sum(#0{x})]
+        Project (#0)
+          ReadStorage materialize.public.t1
+  Return
+    Project (#1)
+      Map ((#0{"?column?"} + 5))
+        Union
+          Get l0
+          Map (null)
+            Union
+              Negate
+                Project ()
+                  Get l0
+              Constant
+                - ()
+
+Source materialize.public.t1
+
+Target cluster: quickstart
+
+EOF

test/sqllogictest/mzcompose.py

@@ -262,6 +262,7 @@ def compileFastSltConfig() -> SltRunConfig:
         "test/sqllogictest/github-5536.slt",
         "test/sqllogictest/github-5717.slt",
         "test/sqllogictest/github-7585.slt",
+        "test/sqllogictest/github-31878.slt",
         "test/sqllogictest/id.slt",
         "test/sqllogictest/id_reuse.slt",
         "test/sqllogictest/information_schema_columns.slt",