Make all ereport() calls within gram.y provide error locations.

This patch responds to a comment that I (tgl) made in the
discussion leading up to 774171c4f, that really all errors
occurring during raw parsing should provide error cursors.
Syntax errors reported by Bison will have one, and most of
the handwritten ereport's in gram.y already provide one,
but there were a few stragglers.

(It is not claimed that this handles every failure reachable
during raw parsing --- out-of-memory is an obvious exception.
But this makes a good start on cases that are likely to occur.)

While we're at it, clean up the reported positions for errors
associated with LIMIT/OFFSET clauses.  Previously we were
relying on applying exprLocation() to the contained expressions,
but that leads to slightly odd cursor placement, e.g.

regression=# (select * from foo limit 10) limit 10;
ERROR:  multiple LIMIT clauses not allowed
LINE 1: (select * from foo limit 10) limit 10;
                                           ^

We can afford to keep a little more state in the transient
SelectLimit structs in order to make that better.

Jian He and Tom Lane (extracted from a larger patch by Jian,
with some additional work by me)

Discussion: https://postgr.es/m/CACJufxEmONE3P2En=jopZy1m=cCCUs65M4+1o52MW5og9oaUPA@mail.gmail.com

1 files changed, 52 insertions, 22 deletions

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index c96505f8b4e..89fdb94c237 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -105,12 +105,15 @@ typedef struct ImportQual
 	List	   *table_names;
 } ImportQual;
 
-/* Private struct for the result of opt_select_limit production */
+/* Private struct for the result of select_limit & limit_clause productions */
 typedef struct SelectLimit
 {
 	Node	   *limitOffset;
 	Node	   *limitCount;
-	LimitOption limitOption;
+	LimitOption limitOption;	/* indicates presence of WITH TIES */
+	ParseLoc	offsetLoc;		/* location of OFFSET token, if present */
+	ParseLoc	countLoc;		/* location of LIMIT/FETCH token, if present */
+	ParseLoc	optionLoc;		/* location of WITH TIES, if present */
 } SelectLimit;
 
 /* Private struct for the result of group_clause production */
@@ -195,7 +198,8 @@ static void SplitColQualList(List *qualList,
 static void processCASbits(int cas_bits, int location, const char *constrType,
 			   bool *deferrable, bool *initdeferred, bool *not_valid,
 			   bool *no_inherit, core_yyscan_t yyscanner);
-static PartitionStrategy parsePartitionStrategy(char *strategy);
+static PartitionStrategy parsePartitionStrategy(char *strategy, int location,
+												core_yyscan_t yyscanner);
 static void preprocess_pubobj_list(List *pubobjspec_list,
 								   core_yyscan_t yyscanner);
 static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
@@ -3145,11 +3149,13 @@ PartitionBoundSpec:
 					if (n->modulus == -1)
 						ereport(ERROR,
 								(errcode(ERRCODE_SYNTAX_ERROR),
-								 errmsg("modulus for hash partition must be specified")));
+								 errmsg("modulus for hash partition must be specified"),
+								 parser_errposition(@3)));
 					if (n->remainder == -1)
 						ereport(ERROR,
 								(errcode(ERRCODE_SYNTAX_ERROR),
-								 errmsg("remainder for hash partition must be specified")));
+								 errmsg("remainder for hash partition must be specified"),
+								 parser_errposition(@3)));
 
 					n->location = @3;
 
@@ -4528,7 +4534,7 @@ PartitionSpec: PARTITION BY ColId '(' part_params ')'
 				{
 					PartitionSpec *n = makeNode(PartitionSpec);
 
-					n->strategy = parsePartitionStrategy($3);
+					n->strategy = parsePartitionStrategy($3, @3, yyscanner);
 					n->partParams = $5;
 					n->location = @1;
 
@@ -5962,7 +5968,8 @@ CreateTrigStmt:
 					if (n->replace) /* not supported, see CreateTrigger */
 						ereport(ERROR,
 								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-								 errmsg("CREATE OR REPLACE CONSTRAINT TRIGGER is not supported")));
+								 errmsg("CREATE OR REPLACE CONSTRAINT TRIGGER is not supported"),
+								 parser_errposition(@1)));
 					n->isconstraint = true;
 					n->trigname = $5;
 					n->relation = $9;
@@ -6247,7 +6254,8 @@ CreateAssertionStmt:
 				{
 					ereport(ERROR,
 							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-							 errmsg("CREATE ASSERTION is not yet implemented")));
+							 errmsg("CREATE ASSERTION is not yet implemented"),
+							 parser_errposition(@1)));
 
 					$$ = NULL;
 				}
@@ -13156,11 +13164,13 @@ select_limit:
 				{
 					$$ = $1;
 					($$)->limitOffset = $2;
+					($$)->offsetLoc = @2;
 				}
 			| offset_clause limit_clause
 				{
 					$$ = $2;
 					($$)->limitOffset = $1;
+					($$)->offsetLoc = @1;
 				}
 			| limit_clause
 				{
@@ -13173,6 +13183,9 @@ select_limit:
 					n->limitOffset = $1;
 					n->limitCount = NULL;
 					n->limitOption = LIMIT_OPTION_COUNT;
+					n->offsetLoc = @1;
+					n->countLoc = -1;
+					n->optionLoc = -1;
 					$$ = n;
 				}
 		;
@@ -13190,6 +13203,9 @@ limit_clause:
 					n->limitOffset = NULL;
 					n->limitCount = $2;
 					n->limitOption = LIMIT_OPTION_COUNT;
+					n->offsetLoc = -1;
+					n->countLoc = @1;
+					n->optionLoc = -1;
 					$$ = n;
 				}
 			| LIMIT select_limit_value ',' select_offset_value
@@ -13215,6 +13231,9 @@ limit_clause:
 					n->limitOffset = NULL;
 					n->limitCount = $3;
 					n->limitOption = LIMIT_OPTION_COUNT;
+					n->offsetLoc = -1;
+					n->countLoc = @1;
+					n->optionLoc = -1;
 					$$ = n;
 				}
 			| FETCH first_or_next select_fetch_first_value row_or_rows WITH TIES
@@ -13224,6 +13243,9 @@ limit_clause:
 					n->limitOffset = NULL;
 					n->limitCount = $3;
 					n->limitOption = LIMIT_OPTION_WITH_TIES;
+					n->offsetLoc = -1;
+					n->countLoc = @1;
+					n->optionLoc = @5;
 					$$ = n;
 				}
 			| FETCH first_or_next row_or_rows ONLY
@@ -13233,6 +13255,9 @@ limit_clause:
 					n->limitOffset = NULL;
 					n->limitCount = makeIntConst(1, -1);
 					n->limitOption = LIMIT_OPTION_COUNT;
+					n->offsetLoc = -1;
+					n->countLoc = @1;
+					n->optionLoc = -1;
 					$$ = n;
 				}
 			| FETCH first_or_next row_or_rows WITH TIES
@@ -13242,6 +13267,9 @@ limit_clause:
 					n->limitOffset = NULL;
 					n->limitCount = makeIntConst(1, -1);
 					n->limitOption = LIMIT_OPTION_WITH_TIES;
+					n->offsetLoc = -1;
+					n->countLoc = @1;
+					n->optionLoc = @4;
 					$$ = n;
 				}
 		;
@@ -16954,8 +16982,9 @@ json_format_clause:
 						encoding = JS_ENC_UTF32;
 					else
 						ereport(ERROR,
-								errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-								errmsg("unrecognized JSON encoding: %s", $4));
+								(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+								 errmsg("unrecognized JSON encoding: %s", $4),
+								 parser_errposition(@4)));
 
 					$$ = (Node *) makeJsonFormat(JS_FORMAT_JSON, encoding, @1);
 				}
@@ -17457,7 +17486,8 @@ PLpgSQL_Expr: opt_distinct_clause opt_target_list
 							$9->limitOption == LIMIT_OPTION_WITH_TIES)
 							ereport(ERROR,
 									(errcode(ERRCODE_SYNTAX_ERROR),
-									 errmsg("WITH TIES cannot be specified without ORDER BY clause")));
+									 errmsg("WITH TIES cannot be specified without ORDER BY clause"),
+									 parser_errposition($9->optionLoc)));
 						n->limitOption = $9->limitOption;
 					}
 					n->lockingClause = $10;
@@ -18962,7 +18992,7 @@ insertSelectOptions(SelectStmt *stmt,
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 					 errmsg("multiple OFFSET clauses not allowed"),
-					 parser_errposition(exprLocation(limitClause->limitOffset))));
+					 parser_errposition(limitClause->offsetLoc)));
 		stmt->limitOffset = limitClause->limitOffset;
 	}
 	if (limitClause && limitClause->limitCount)
@@ -18971,19 +19001,18 @@ insertSelectOptions(SelectStmt *stmt,
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 					 errmsg("multiple LIMIT clauses not allowed"),
-					 parser_errposition(exprLocation(limitClause->limitCount))));
+					 parser_errposition(limitClause->countLoc)));
 		stmt->limitCount = limitClause->limitCount;
 	}
 	if (limitClause)
 	{
-		if (stmt->limitOption)
-			ereport(ERROR,
-					(errcode(ERRCODE_SYNTAX_ERROR),
-					 errmsg("multiple limit options not allowed")));
+		/* If there was a conflict, we must have detected it above */
+		Assert(!stmt->limitOption);
 		if (!stmt->sortClause && limitClause->limitOption == LIMIT_OPTION_WITH_TIES)
 			ereport(ERROR,
 					(errcode(ERRCODE_SYNTAX_ERROR),
-					 errmsg("WITH TIES cannot be specified without ORDER BY clause")));
+					 errmsg("WITH TIES cannot be specified without ORDER BY clause"),
+					 parser_errposition(limitClause->optionLoc)));
 		if (limitClause->limitOption == LIMIT_OPTION_WITH_TIES && stmt->lockingClause)
 		{
 			ListCell   *lc;
@@ -18996,7 +19025,8 @@ insertSelectOptions(SelectStmt *stmt,
 					ereport(ERROR,
 							(errcode(ERRCODE_SYNTAX_ERROR),
 							 errmsg("%s and %s options cannot be used together",
-									"SKIP LOCKED", "WITH TIES")));
+									"SKIP LOCKED", "WITH TIES"),
+							 parser_errposition(limitClause->optionLoc)));
 			}
 		}
 		stmt->limitOption = limitClause->limitOption;
@@ -19425,7 +19455,7 @@ processCASbits(int cas_bits, int location, const char *constrType,
  * PartitionStrategy representation, or die trying.
  */
 static PartitionStrategy
-parsePartitionStrategy(char *strategy)
+parsePartitionStrategy(char *strategy, int location, core_yyscan_t yyscanner)
 {
 	if (pg_strcasecmp(strategy, "list") == 0)
 		return PARTITION_STRATEGY_LIST;
@@ -19436,8 +19466,8 @@ parsePartitionStrategy(char *strategy)
 
 	ereport(ERROR,
 			(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-			 errmsg("unrecognized partitioning strategy \"%s\"",
-					strategy)));
+			 errmsg("unrecognized partitioning strategy \"%s\"", strategy),
+			 parser_errposition(location)));
 	return PARTITION_STRATEGY_LIST;		/* keep compiler quiet */
 
 }