Merge #129951

129951: parser: allow multiple DECLARE keywords in function definitions r=mw5h a=mw5h

Previously, UDFs with multiple DECLARE statements would cause the parser to panic. This patch allows us to accept these statements, which is what Postgres does.

Fixes: #129285
Release note (bug fix): Using more than one DECLARE statment in the definition of a user defined function now correctly declares additional variables.

Co-authored-by: Matt White <[email protected]>

Author: craig[bot]

pkg/ccl/logictestccl/testdata/logic_test/plpgsql_block

@@ -693,3 +693,40 @@ BEGIN
   END IF;
 END;
 $$ LANGUAGE PLpgSQL;
+
+subtest multi_declare
+
+statement ok
+DROP FUNCTION IF EXISTS f;
+
+statement ok
+CREATE FUNCTION f() RETURNS INT AS $$
+DECLARE
+  x INT := 0;
+DECLARE
+  y INT := x + 1;
+BEGIN
+  RAISE NOTICE '% %', x, y;
+  RETURN 0;
+END;
+$$ LANGUAGE PLpgSQL;
+
+query T noticetrace
+SELECT f();
+----
+NOTICE: 0 1
+
+statement ok
+DROP FUNCTION IF EXISTS f;
+
+statement error pgcode 42601 pq: duplicate declaration at or near "x"
+CREATE FUNCTION f() RETURNS INT AS $$
+DECLARE
+  x INT := 0;
+DECLARE
+  x INT := 1;
+BEGIN
+  RAISE NOTICE '%', x;
+  RETURN 0;
+END;
+$$ LANGUAGE PLpgSQL;

pkg/sql/plpgsql/parser/plpgsql.y

@@ -344,7 +344,7 @@ func (u *plpgsqlSymUnion) sqlStatement() tree.Statement {
 %type <plpgsqltree.Statement>	stmt_commit stmt_rollback
 %type <plpgsqltree.Statement>	stmt_case stmt_foreach_a
 
-%type <plpgsqltree.Statement> decl_stmt decl_statement
+%type <plpgsqltree.Statement> decl_statement
 %type <[]plpgsqltree.Statement> decl_sect opt_decl_stmts decl_stmts
 
 %type <[]plpgsqltree.Exception> exception_sect proc_exceptions
@@ -419,36 +419,23 @@ opt_decl_stmts: decl_stmts
   }
 ;
 
-decl_stmts: decl_stmts decl_stmt
+opt_declare: DECLARE {}
+| {}
+;
+
+decl_stmts: decl_stmts opt_declare decl_statement
   {
     decs := $1.statements()
-    dec := $2.statement()
+    dec := $3.statement()
     $$.val = append(decs, dec)
   }
-| decl_stmt
+| decl_statement
   {
     dec := $1.statement()
     $$.val = []plpgsqltree.Statement{dec}
 	}
 ;
 
-decl_stmt	: decl_statement
-  {
-    $$.val = $1.statement()
-  }
-| DECLARE
-  {
-    // This is to allow useless extra "DECLARE" keywords in the declare section.
-    $$.val = (plpgsqltree.Statement)(nil)
-  }
-// TODO(drewk): turn this block on and throw useful error if user
-// tries to put the block label just before BEGIN instead of before
-// DECLARE.
-//| LESS_LESS any_identifier GREATER_GREATER
-//  {
-//  }
-;
-
 decl_statement: decl_varname decl_const decl_datatype decl_collate decl_notnull decl_defval
   {
     $$.val = &plpgsqltree.Declaration{