v6-0001-Allow-transformation-only-of-a-sublist-of-subscri.patch

From d4df1c1db6d64651bb0f7358561ca84231a55090 Mon Sep 17 00:00:00 2001
From: Nikita Glukhov <n.gluhov@postgrespro.ru>
Date: Fri, 14 Oct 2022 15:35:22 +0300
Subject: [PATCH v6 01/11] Allow transformation only of a sublist of subscripts

---
 contrib/hstore/expected/hstore.out |  4 +++-
 contrib/hstore/hstore_subs.c       | 11 +++++++----
 src/backend/parser/parse_expr.c    |  9 ++++-----
 src/backend/parser/parse_node.c    |  4 ++--
 src/backend/parser/parse_target.c  |  5 ++++-
 src/backend/utils/adt/arraysubs.c  |  5 +++--
 src/backend/utils/adt/jsonbsubs.c  |  6 ++++--
 src/include/nodes/subscripting.h   |  2 +-
 src/include/parser/parse_node.h    |  2 +-
 9 files changed, 29 insertions(+), 19 deletions(-)

diff --git a/contrib/hstore/expected/hstore.out b/contrib/hstore/expected/hstore.out
index 1836c9acf39..9e2421750fb 100644
--- a/contrib/hstore/expected/hstore.out
+++ b/contrib/hstore/expected/hstore.out
@@ -1605,7 +1605,9 @@ select f2['d'], f2['x'] is null as x_isnull from test_json_agg;
 (3 rows)
 
 select f2['d']['e'] from test_json_agg;  -- error
-ERROR:  hstore allows only one subscript
+ERROR:  cannot subscript type text because it does not support subscripting
+LINE 1: select f2['d']['e'] from test_json_agg;
+               ^
 select f2['d':'e'] from test_json_agg;  -- error
 ERROR:  hstore allows only one subscript
 update test_json_agg set f2['d'] = f2['e'], f2['x'] = 'xyzzy';
diff --git a/contrib/hstore/hstore_subs.c b/contrib/hstore/hstore_subs.c
index 1443d8634b2..efdd0f22ac1 100644
--- a/contrib/hstore/hstore_subs.c
+++ b/contrib/hstore/hstore_subs.c
@@ -40,7 +40,7 @@
  */
 static void
 hstore_subscript_transform(SubscriptingRef *sbsref,
-						   List *indirection,
+						   List **indirection,
 						   ParseState *pstate,
 						   bool isSlice,
 						   bool isAssignment)
@@ -49,17 +49,20 @@ hstore_subscript_transform(SubscriptingRef *sbsref,
 	Node	   *subexpr;
 
 	/* We support only single-subscript, non-slice cases */
-	if (isSlice || list_length(indirection) != 1)
+	if (isSlice || list_length(*indirection) < 1)
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("hstore allows only one subscript"),
 				 parser_errposition(pstate,
-									exprLocation((Node *) indirection))));
+									exprLocation((Node *) *indirection))));
 
 	/* Transform the subscript expression to type text */
-	ai = linitial_node(A_Indices, indirection);
+	ai = linitial_node(A_Indices, *indirection);
 	Assert(ai->uidx != NULL && ai->lidx == NULL && !ai->is_slice);
 
+	/* hstore allows only one subscript */
+	*indirection = list_delete_first(*indirection);
+
 	subexpr = transformExpr(pstate, ai->uidx, pstate->p_expr_kind);
 	/* If it's not text already, try to coerce */
 	subexpr = coerce_to_target_type(pstate,
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index c2806297aa4..7d57bde8134 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -466,14 +466,13 @@ transformIndirection(ParseState *pstate, A_Indirection *ind)
 			Assert(IsA(n, String));
 
 			/* process subscripts before this field selection */
-			if (subscripts)
+			while (subscripts)
 				result = (Node *) transformContainerSubscripts(pstate,
 															   result,
 															   exprType(result),
 															   exprTypmod(result),
-															   subscripts,
+															   &subscripts,
 															   false);
-			subscripts = NIL;
 
 			newresult = ParseFuncOrColumn(pstate,
 										  list_make1(n),
@@ -488,12 +487,12 @@ transformIndirection(ParseState *pstate, A_Indirection *ind)
 		}
 	}
 	/* process trailing subscripts, if any */
-	if (subscripts)
+	while (subscripts)
 		result = (Node *) transformContainerSubscripts(pstate,
 													   result,
 													   exprType(result),
 													   exprTypmod(result),
-													   subscripts,
+													   &subscripts,
 													   false);
 
 	return result;
diff --git a/src/backend/parser/parse_node.c b/src/backend/parser/parse_node.c
index 9361b5252d8..a24ae783b5f 100644
--- a/src/backend/parser/parse_node.c
+++ b/src/backend/parser/parse_node.c
@@ -244,7 +244,7 @@ transformContainerSubscripts(ParseState *pstate,
 							 Node *containerBase,
 							 Oid containerType,
 							 int32 containerTypMod,
-							 List *indirection,
+							 List **indirection,
 							 bool isAssignment)
 {
 	SubscriptingRef *sbsref;
@@ -280,7 +280,7 @@ transformContainerSubscripts(ParseState *pstate,
 	 * element.  If any of the items are slice specifiers (lower:upper), then
 	 * the subscript expression means a container slice operation.
 	 */
-	foreach(idx, indirection)
+	foreach(idx, *indirection)
 	{
 		A_Indices  *ai = lfirst_node(A_Indices, idx);
 
diff --git a/src/backend/parser/parse_target.c b/src/backend/parser/parse_target.c
index 76bf88c3ca2..9bed545eb00 100644
--- a/src/backend/parser/parse_target.c
+++ b/src/backend/parser/parse_target.c
@@ -936,9 +936,12 @@ transformAssignmentSubscripts(ParseState *pstate,
 										  basenode,
 										  containerType,
 										  containerTypMod,
-										  subscripts,
+										  &subscripts,
 										  true);
 
+	if (subscripts)
+		elog(ERROR, "subscripting assignment is not supported");
+
 	typeNeeded = sbsref->refrestype;
 	typmodNeeded = sbsref->reftypmod;
 
diff --git a/src/backend/utils/adt/arraysubs.c b/src/backend/utils/adt/arraysubs.c
index 6f68dfa5b23..d590fdb6958 100644
--- a/src/backend/utils/adt/arraysubs.c
+++ b/src/backend/utils/adt/arraysubs.c
@@ -53,7 +53,7 @@ typedef struct ArraySubWorkspace
  */
 static void
 array_subscript_transform(SubscriptingRef *sbsref,
-						  List *indirection,
+						  List **indirection,
 						  ParseState *pstate,
 						  bool isSlice,
 						  bool isAssignment)
@@ -70,7 +70,7 @@ array_subscript_transform(SubscriptingRef *sbsref,
 	 * indirection items to slices by treating the single subscript as the
 	 * upper bound and supplying an assumed lower bound of 1.
 	 */
-	foreach(idx, indirection)
+	foreach(idx, *indirection)
 	{
 		A_Indices  *ai = lfirst_node(A_Indices, idx);
 		Node	   *subexpr;
@@ -151,6 +151,7 @@ array_subscript_transform(SubscriptingRef *sbsref,
 						list_length(upperIndexpr), MAXDIM)));
 	/* We need not check lowerIndexpr separately */
 
+		*indirection = NIL;
 	/*
 	 * Determine the result type of the subscripting operation.  It's the same
 	 * as the array type if we're slicing, else it's the element type.  In
diff --git a/src/backend/utils/adt/jsonbsubs.c b/src/backend/utils/adt/jsonbsubs.c
index 2b037131c91..d37ee004e16 100644
--- a/src/backend/utils/adt/jsonbsubs.c
+++ b/src/backend/utils/adt/jsonbsubs.c
@@ -41,7 +41,7 @@ typedef struct JsonbSubWorkspace
  */
 static void
 jsonb_subscript_transform(SubscriptingRef *sbsref,
-						  List *indirection,
+						  List **indirection,
 						  ParseState *pstate,
 						  bool isSlice,
 						  bool isAssignment)
@@ -53,7 +53,7 @@ jsonb_subscript_transform(SubscriptingRef *sbsref,
 	 * Transform and convert the subscript expressions. Jsonb subscripting
 	 * does not support slices, look only and the upper index.
 	 */
-	foreach(idx, indirection)
+	foreach(idx, *indirection)
 	{
 		A_Indices  *ai = lfirst_node(A_Indices, idx);
 		Node	   *subExpr;
@@ -159,6 +159,8 @@ jsonb_subscript_transform(SubscriptingRef *sbsref,
 	/* Determine the result type of the subscripting operation; always jsonb */
 	sbsref->refrestype = JSONBOID;
 	sbsref->reftypmod = -1;
+
+	*indirection = NIL;
 }
 
 /*
diff --git a/src/include/nodes/subscripting.h b/src/include/nodes/subscripting.h
index 597209ba42d..11a8ea9c1e0 100644
--- a/src/include/nodes/subscripting.h
+++ b/src/include/nodes/subscripting.h
@@ -93,7 +93,7 @@ struct SubscriptExecSteps;
  * assignment must return.
  */
 typedef void (*SubscriptTransform) (SubscriptingRef *sbsref,
-									List *indirection,
+									List **indirection,
 									struct ParseState *pstate,
 									bool isSlice,
 									bool isAssignment);
diff --git a/src/include/parser/parse_node.h b/src/include/parser/parse_node.h
index 2375e95c107..195bd4dccb8 100644
--- a/src/include/parser/parse_node.h
+++ b/src/include/parser/parse_node.h
@@ -370,7 +370,7 @@ extern SubscriptingRef *transformContainerSubscripts(ParseState *pstate,
 													 Node *containerBase,
 													 Oid containerType,
 													 int32 containerTypMod,
-													 List *indirection,
+													 List **indirection,
 													 bool isAssignment);
 extern Const *make_const(ParseState *pstate, A_Const *aconst);
 
-- 
2.25.1