sql: add parsing support for SHOW CREATE FUNCTION statement

This commit adds a `SHOW CREATE FUNCTION` statement to the SQL grammar.
This statement is not yet implemented and executing it results in an
error.

Release note: None

pkg/sql/delegate/BUILD.bazel

@@ -14,6 +14,7 @@ go_library(
         "show_default_privileges.go",
         "show_enums.go",
         "show_full_table_scans.go",
+        "show_function.go",
         "show_grants.go",
         "show_jobs.go",
         "show_partitions.go",

pkg/sql/delegate/delegate.go

@@ -58,6 +58,9 @@ func TryDelegate(
 	case *tree.ShowCreate:
 		return d.delegateShowCreate(t)
 
+	case *tree.ShowCreateFunction:
+		return d.delegateShowCreateFunction(t)
+
 	case *tree.ShowCreateAllSchemas:
 		return d.delegateShowCreateAllSchemas()
 

pkg/sql/delegate/show_function.go

@@ -0,0 +1,20 @@
+// Copyright 2022 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// 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, included in the file
+// licenses/APL.txt.
+
+package delegate
+
+import (
+	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
+	"github.com/cockroachdb/cockroach/pkg/util/errorutil/unimplemented"
+)
+
+func (d *delegator) delegateShowCreateFunction(n *tree.ShowCreateFunction) (tree.Statement, error) {
+	return nil, unimplemented.New("SHOW CREATE FUNCTION", "this statement is not yet supported")
+}

pkg/sql/logictest/testdata/logic_test/show_create

@@ -140,3 +140,8 @@ CREATE TABLE public.t (
   CONSTRAINT t_pkey PRIMARY KEY (rowid ASC)
 );
 COMMENT ON COLUMN public.t.c IS 'first comment'
+
+subtest show_create_function
+
+statement error this statement is not yet supported
+SHOW CREATE FUNCTION lower

pkg/sql/parser/sql.y

@@ -5679,8 +5679,9 @@ zone_value:
 // %Category: Group
 // %Text:
 // SHOW BACKUP, SHOW CLUSTER SETTING, SHOW COLUMNS, SHOW CONSTRAINTS,
-// SHOW CREATE, SHOW CREATE SCHEDULES, SHOW DATABASES, SHOW ENUMS, SHOW HISTOGRAM, SHOW INDEXES, SHOW
-// PARTITIONS, SHOW JOBS, SHOW STATEMENTS, SHOW RANGE, SHOW RANGES, SHOW REGIONS, SHOW SURVIVAL GOAL,
+// SHOW CREATE, SHOW CREATE SCHEDULES, SHOW DATABASES, SHOW ENUMS, SHOW
+// FUNCTION, SHOW HISTOGRAM, SHOW INDEXES, SHOW PARTITIONS, SHOW JOBS, SHOW
+// STATEMENTS, SHOW RANGE, SHOW RANGES, SHOW REGIONS, SHOW SURVIVAL GOAL,
 // SHOW ROLES, SHOW SCHEMAS, SHOW SEQUENCES, SHOW SESSION, SHOW SESSIONS,
 // SHOW STATISTICS, SHOW SYNTAX, SHOW TABLES, SHOW TRACE, SHOW TRANSACTION,
 // SHOW TRANSACTIONS, SHOW TRANSFER, SHOW TYPES, SHOW USERS, SHOW LAST QUERY STATISTICS,
@@ -6760,6 +6761,15 @@ show_create_stmt:
     /* SKIP DOC */
     $$.val = &tree.ShowCreate{Mode: tree.ShowCreateModeDatabase, Name: $4.unresolvedObjectName()}
 	}
+| SHOW CREATE FUNCTION db_object_name
+  {
+    /* SKIP DOC */
+    $$.val = &tree.ShowCreateFunction{
+      Name: tree.ResolvableFunctionReference{
+        FunctionReference: $4.unresolvedObjectName().ToUnresolvedName(),
+      },
+    }
+  }
 | SHOW CREATE ALL SCHEMAS
   {
     $$.val = &tree.ShowCreateAllSchemas{}

pkg/sql/parser/testdata/show

@@ -1754,3 +1754,27 @@ SHOW client_encoding -- normalized!
 SHOW client_encoding -- fully parenthesized
 SHOW client_encoding -- literals removed
 SHOW client_encoding -- identifiers removed
+
+parse
+SHOW CREATE FUNCTION foo
+----
+SHOW CREATE FUNCTION foo
+SHOW CREATE FUNCTION foo -- fully parenthesized
+SHOW CREATE FUNCTION foo -- literals removed
+SHOW CREATE FUNCTION _ -- identifiers removed
+
+parse
+SHOW CREATE FUNCTION db.foo
+----
+SHOW CREATE FUNCTION db.foo
+SHOW CREATE FUNCTION db.foo -- fully parenthesized
+SHOW CREATE FUNCTION db.foo -- literals removed
+SHOW CREATE FUNCTION _._ -- identifiers removed
+
+parse
+SHOW CREATE FUNCTION db.sch.foo
+----
+SHOW CREATE FUNCTION db.sch.foo
+SHOW CREATE FUNCTION db.sch.foo -- fully parenthesized
+SHOW CREATE FUNCTION db.sch.foo -- literals removed
+SHOW CREATE FUNCTION _._._ -- identifiers removed

pkg/sql/sem/tree/show.go

@@ -944,3 +944,16 @@ func (s ShowCompletions) Format(ctx *FmtCtx) {
 }
 
 var _ Statement = &ShowCompletions{}
+
+// ShowCreateFunction represents a SHOW CREATE FUNCTION statement.
+type ShowCreateFunction struct {
+	Name ResolvableFunctionReference
+}
+
+// Format implements the NodeFormatter interface.
+func (node *ShowCreateFunction) Format(ctx *FmtCtx) {
+	ctx.WriteString("SHOW CREATE FUNCTION ")
+	ctx.FormatNode(&node.Name)
+}
+
+var _ Statement = &ShowCreateFunction{}

pkg/sql/sem/tree/stmt.go

@@ -1714,6 +1714,15 @@ func (*ShowCompletions) observerStatement() {}
 
 func (*ShowCompletions) hiddenFromShowQueries() {}
 
+// StatementReturnType implements the Statement interface.
+func (*ShowCreateFunction) StatementReturnType() StatementReturnType { return Rows }
+
+// StatementType implements the Statement interface.
+func (*ShowCreateFunction) StatementType() StatementType { return TypeDML }
+
+// StatementTag returns a short string identifying the type of statement.
+func (*ShowCreateFunction) StatementTag() string { return "SHOW CREATE FUNCTION" }
+
 // StatementReturnType implements the Statement interface.
 func (*Split) StatementReturnType() StatementReturnType { return Rows }
 
@@ -1926,14 +1935,15 @@ func (n *ShowTenantClusterSettingList) String() string   { return AsString(n) }
 func (n *ShowColumns) String() string                    { return AsString(n) }
 func (n *ShowConstraints) String() string                { return AsString(n) }
 func (n *ShowCreate) String() string                     { return AsString(n) }
-func (node *ShowCreateAllSchemas) String() string        { return AsString(node) }
-func (node *ShowCreateAllTables) String() string         { return AsString(node) }
-func (node *ShowCreateAllTypes) String() string          { return AsString(node) }
+func (n *ShowCreateAllSchemas) String() string           { return AsString(n) }
+func (n *ShowCreateAllTables) String() string            { return AsString(n) }
+func (n *ShowCreateAllTypes) String() string             { return AsString(n) }
 func (n *ShowCreateSchedules) String() string            { return AsString(n) }
 func (n *ShowDatabases) String() string                  { return AsString(n) }
 func (n *ShowDatabaseIndexes) String() string            { return AsString(n) }
 func (n *ShowEnums) String() string                      { return AsString(n) }
 func (n *ShowFullTableScans) String() string             { return AsString(n) }
+func (n *ShowCreateFunction) String() string             { return AsString(n) }
 func (n *ShowGrants) String() string                     { return AsString(n) }
 func (n *ShowHistogram) String() string                  { return AsString(n) }
 func (n *ShowSchedules) String() string                  { return AsString(n) }