Clean up some edge cases in plpgsql's %TYPE parsing.

Support referencing a composite-type variable in %TYPE.

Remove the undocumented, untested, and pretty useless ability
to have the subject of %TYPE be an (unqualified) type name.
You get the same result by just not writing %TYPE.

Add or adjust some test cases to improve code coverage here.

Discussion: https://postgr.es/m/716852.1704402127@sss.pgh.pa.us

Author: tglsfdc

src/pl/plpgsql/src/expected/plpgsql_record.out

@@ -306,6 +306,52 @@ NOTICE:  r1 = (1,2)
 ERROR:  record "r1" has no field "nosuchfield"
 CONTEXT:  SQL expression "r1.nosuchfield"
 PL/pgSQL function inline_code_block line 9 at RAISE
+-- check %type with block-qualified variable names
+do $$
+<<blk>>
+declare
+  v int;
+  r two_int8s;
+  v1 v%type;
+  v2 blk.v%type;
+  r1 r%type;
+  r2 blk.r%type;
+begin
+  raise notice '%', pg_typeof(v1);
+  raise notice '%', pg_typeof(v2);
+  raise notice '%', pg_typeof(r1);
+  raise notice '%', pg_typeof(r2);
+end$$;
+NOTICE:  integer
+NOTICE:  integer
+NOTICE:  two_int8s
+NOTICE:  two_int8s
+-- check that type record can be passed through %type
+do $$
+declare r1 record;
+        r2 r1%type;
+begin
+  r2 := row(1,2);
+  raise notice 'r2 = %', r2;
+  r2 := row(3,4,5);
+  raise notice 'r2 = %', r2;
+end$$;
+NOTICE:  r2 = (1,2)
+NOTICE:  r2 = (3,4,5)
+-- arrays of record are not supported at the moment
+do $$
+declare r1 record[];
+begin
+end$$;
+ERROR:  variable "r1" has pseudo-type record[]
+CONTEXT:  compilation of PL/pgSQL function "inline_code_block" near line 2
+do $$
+declare r1 record;
+        r2 r1%type[];
+begin
+end$$;
+ERROR:  variable "r2" has pseudo-type record[]
+CONTEXT:  compilation of PL/pgSQL function "inline_code_block" near line 3
 -- check repeated assignments to composite fields
 create table some_table (id int, data text);
 do $$

src/pl/plpgsql/src/pl_comp.c

@@ -1596,19 +1596,16 @@ plpgsql_parse_tripword(char *word1, char *word2, char *word3,
 
 
 /* ----------
- * plpgsql_parse_wordtype	The scanner found word%TYPE. word can be
- *				a variable name or a basetype.
+ * plpgsql_parse_wordtype	The scanner found word%TYPE. word should be
+ *				a pre-existing variable name.
  *
  * Returns datatype struct, or NULL if no match found for word.
  * ----------
  */
 PLpgSQL_type *
 plpgsql_parse_wordtype(char *ident)
 {
-	PLpgSQL_type *dtype;
 	PLpgSQL_nsitem *nse;
-	TypeName   *typeName;
-	HeapTuple	typeTup;
 
 	/*
 	 * Do a lookup in the current namespace stack
@@ -1623,39 +1620,13 @@ plpgsql_parse_wordtype(char *ident)
 		{
 			case PLPGSQL_NSTYPE_VAR:
 				return ((PLpgSQL_var *) (plpgsql_Datums[nse->itemno]))->datatype;
-
-				/* XXX perhaps allow REC/ROW here? */
-
+			case PLPGSQL_NSTYPE_REC:
+				return ((PLpgSQL_rec *) (plpgsql_Datums[nse->itemno]))->datatype;
 			default:
 				return NULL;
 		}
 	}
 
-	/*
-	 * Word wasn't found in the namespace stack. Try to find a data type with
-	 * that name, but ignore shell types and complex types.
-	 */
-	typeName = makeTypeName(ident);
-	typeTup = LookupTypeName(NULL, typeName, NULL, false);
-	if (typeTup)
-	{
-		Form_pg_type typeStruct = (Form_pg_type) GETSTRUCT(typeTup);
-
-		if (!typeStruct->typisdefined ||
-			typeStruct->typrelid != InvalidOid)
-		{
-			ReleaseSysCache(typeTup);
-			return NULL;
-		}
-
-		dtype = build_datatype(typeTup, -1,
-							   plpgsql_curr_compile->fn_input_collation,
-							   typeName);
-
-		ReleaseSysCache(typeTup);
-		return dtype;
-	}
-
 	/*
 	 * Nothing found - up to now it's a word without any special meaning for
 	 * us.
@@ -1666,13 +1637,17 @@ plpgsql_parse_wordtype(char *ident)
 
 /* ----------
  * plpgsql_parse_cwordtype		Same lookup for compositeword%TYPE
+ *
+ * Here, we allow either a block-qualified variable name, or a reference
+ * to a column of some table.
  * ----------
  */
 PLpgSQL_type *
 plpgsql_parse_cwordtype(List *idents)
 {
 	PLpgSQL_type *dtype = NULL;
 	PLpgSQL_nsitem *nse;
+	int			nnames;
 	const char *fldname;
 	Oid			classOid;
 	HeapTuple	classtup = NULL;
@@ -1688,21 +1663,27 @@ plpgsql_parse_cwordtype(List *idents)
 	if (list_length(idents) == 2)
 	{
 		/*
-		 * Do a lookup in the current namespace stack. We don't need to check
-		 * number of names matched, because we will only consider scalar
-		 * variables.
+		 * Do a lookup in the current namespace stack
 		 */
 		nse = plpgsql_ns_lookup(plpgsql_ns_top(), false,
 								strVal(linitial(idents)),
 								strVal(lsecond(idents)),
 								NULL,
-								NULL);
+								&nnames);
 
 		if (nse != NULL && nse->itemtype == PLPGSQL_NSTYPE_VAR)
 		{
+			/* Block-qualified reference to scalar variable. */
 			dtype = ((PLpgSQL_var *) (plpgsql_Datums[nse->itemno]))->datatype;
 			goto done;
 		}
+		else if (nse != NULL && nse->itemtype == PLPGSQL_NSTYPE_REC &&
+				 nnames == 2)
+		{
+			/* Block-qualified reference to record variable. */
+			dtype = ((PLpgSQL_rec *) (plpgsql_Datums[nse->itemno]))->datatype;
+			goto done;
+		}
 
 		/*
 		 * First word could also be a table name
@@ -1716,6 +1697,12 @@ plpgsql_parse_cwordtype(List *idents)
 	{
 		RangeVar   *relvar;
 
+		/*
+		 * We could check for a block-qualified reference to a field of a
+		 * record variable, but %TYPE is documented as applying to variables,
+		 * not fields of variables.  Things would get rather ambiguous if we
+		 * allowed either interpretation.
+		 */
 		relvar = makeRangeVar(strVal(linitial(idents)),
 							  strVal(lsecond(idents)),
 							  -1);

src/pl/plpgsql/src/sql/plpgsql_record.sql

@@ -199,6 +199,46 @@ begin
   raise notice 'r1.nosuchfield = %', r1.nosuchfield;
 end$$;
 
+-- check %type with block-qualified variable names
+do $$
+<<blk>>
+declare
+  v int;
+  r two_int8s;
+  v1 v%type;
+  v2 blk.v%type;
+  r1 r%type;
+  r2 blk.r%type;
+begin
+  raise notice '%', pg_typeof(v1);
+  raise notice '%', pg_typeof(v2);
+  raise notice '%', pg_typeof(r1);
+  raise notice '%', pg_typeof(r2);
+end$$;
+
+-- check that type record can be passed through %type
+do $$
+declare r1 record;
+        r2 r1%type;
+begin
+  r2 := row(1,2);
+  raise notice 'r2 = %', r2;
+  r2 := row(3,4,5);
+  raise notice 'r2 = %', r2;
+end$$;
+
+-- arrays of record are not supported at the moment
+do $$
+declare r1 record[];
+begin
+end$$;
+
+do $$
+declare r1 record;
+        r2 r1%type[];
+begin
+end$$;
+
 -- check repeated assignments to composite fields
 create table some_table (id int, data text);
 

src/test/regress/expected/plpgsql.out

@@ -5795,18 +5795,18 @@ SELECT * FROM get_from_partitioned_table(1) AS t;
 (1 row)
 
 CREATE OR REPLACE FUNCTION list_partitioned_table()
-RETURNS SETOF partitioned_table.a%TYPE AS $$
+RETURNS SETOF public.partitioned_table.a%TYPE AS $$
 DECLARE
-    row partitioned_table%ROWTYPE;
-    a_val partitioned_table.a%TYPE;
+    row public.partitioned_table%ROWTYPE;
+    a_val public.partitioned_table.a%TYPE;
 BEGIN
-    FOR row IN SELECT * FROM partitioned_table ORDER BY a LOOP
+    FOR row IN SELECT * FROM public.partitioned_table ORDER BY a LOOP
         a_val := row.a;
         RETURN NEXT a_val;
     END LOOP;
     RETURN;
 END; $$ LANGUAGE plpgsql;
-NOTICE:  type reference partitioned_table.a%TYPE converted to integer
+NOTICE:  type reference public.partitioned_table.a%TYPE converted to integer
 SELECT * FROM list_partitioned_table() AS t;
  t 
 ---

src/test/regress/sql/plpgsql.sql

@@ -4734,12 +4734,12 @@ END; $$ LANGUAGE plpgsql;
 SELECT * FROM get_from_partitioned_table(1) AS t;
 
 CREATE OR REPLACE FUNCTION list_partitioned_table()
-RETURNS SETOF partitioned_table.a%TYPE AS $$
+RETURNS SETOF public.partitioned_table.a%TYPE AS $$
 DECLARE
-    row partitioned_table%ROWTYPE;
-    a_val partitioned_table.a%TYPE;
+    row public.partitioned_table%ROWTYPE;
+    a_val public.partitioned_table.a%TYPE;
 BEGIN
-    FOR row IN SELECT * FROM partitioned_table ORDER BY a LOOP
+    FOR row IN SELECT * FROM public.partitioned_table ORDER BY a LOOP
         a_val := row.a;
         RETURN NEXT a_val;
     END LOOP;