Rework parsing of ConstraintAttributeSpec to improve NOT VALID handling.

The initial commit of the ALTER TABLE ADD FOREIGN KEY NOT VALID feature
failed to support labeling such constraints as deferrable.  The best fix
for this seems to be to fold NOT VALID into ConstraintAttributeSpec.
That's a bit more general than the documented syntax, but it allows
better-targeted syntax error messages.

In addition, do some mostly-but-not-entirely-cosmetic code review for
the whole NOT VALID patch.

2 files changed, 130 insertions, 75 deletions

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 1d39674de4c..62cff8a7de3 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -94,6 +94,13 @@ typedef struct PrivTarget
 	List	   *objs;
 } PrivTarget;
 
+/* ConstraintAttributeSpec yields an integer bitmask of these flags: */
+#define CAS_NOT_DEFERRABLE			0x01
+#define CAS_DEFERRABLE				0x02
+#define CAS_INITIALLY_IMMEDIATE		0x04
+#define CAS_INITIALLY_DEFERRED		0x08
+#define CAS_NOT_VALID				0x10
+
 
 #define parser_yyerror(msg)  scanner_yyerror(msg, yyscanner)
 #define parser_errposition(pos)  scanner_errposition(pos, yyscanner)
@@ -135,6 +142,9 @@ static RangeVar *makeRangeVarFromAnyName(List *names, int position, core_yyscan_
 static void SplitColQualList(List *qualList,
 							 List **constraintList, CollateClause **collClause,
 							 core_yyscan_t yyscanner);
+static void processCASbits(int cas_bits, int location, const char *constrType,
+			   bool *deferrable, bool *initdeferred, bool *not_valid,
+			   core_yyscan_t yyscanner);
 
 %}
 
@@ -429,8 +439,7 @@ static void SplitColQualList(List *qualList,
 %type <list>	ColQualList
 %type <node>	ColConstraint ColConstraintElem ConstraintAttr
 %type <ival>	key_actions key_delete key_match key_update key_action
-%type <ival>	ConstraintAttributeSpec ConstraintDeferrabilitySpec
-				ConstraintTimeSpec
+%type <ival>	ConstraintAttributeSpec ConstraintAttributeElem
 %type <str>		ExistingIndex
 
 %type <list>	constraints_set_list
@@ -2638,7 +2647,7 @@ ColConstraintElem:
 					n->fk_matchtype		= $4;
 					n->fk_upd_action	= (char) ($5 >> 8);
 					n->fk_del_action	= (char) ($5 & 0xFF);
-					n->skip_validation  = FALSE;
+					n->skip_validation  = false;
 					n->initially_valid  = true;
 					$$ = (Node *)n;
 				}
@@ -2654,7 +2663,10 @@ ColConstraintElem:
  * combinations.
  *
  * See also ConstraintAttributeSpec, which can be used in places where
- * there is no parsing conflict.
+ * there is no parsing conflict.  (Note: currently, NOT VALID is an allowed
+ * clause in ConstraintAttributeSpec, but not here.  Someday we might need
+ * to allow it here too, but for the moment it doesn't seem useful in the
+ * statements that use ConstraintAttr.)
  */
 ConstraintAttr:
 			DEFERRABLE
@@ -2746,11 +2758,9 @@ ConstraintElem:
 					n->location = @1;
 					n->raw_expr = $3;
 					n->cooked_expr = NULL;
-					if ($5 != 0)
-						ereport(ERROR,
-								(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-								 errmsg("CHECK constraints cannot be deferred"),
-								 parser_errposition(@5)));
+					processCASbits($5, @5, "CHECK",
+								   NULL, NULL, NULL,
+								   yyscanner);
 					$$ = (Node *)n;
 				}
 			| UNIQUE '(' columnList ')' opt_definition OptConsTableSpace
@@ -2763,8 +2773,9 @@ ConstraintElem:
 					n->options = $5;
 					n->indexname = NULL;
 					n->indexspace = $6;
-					n->deferrable = ($7 & 1) != 0;
-					n->initdeferred = ($7 & 2) != 0;
+					processCASbits($7, @7, "UNIQUE",
+								   &n->deferrable, &n->initdeferred, NULL,
+								   yyscanner);
 					$$ = (Node *)n;
 				}
 			| UNIQUE ExistingIndex ConstraintAttributeSpec
@@ -2776,8 +2787,9 @@ ConstraintElem:
 					n->options = NIL;
 					n->indexname = $2;
 					n->indexspace = NULL;
-					n->deferrable = ($3 & 1) != 0;
-					n->initdeferred = ($3 & 2) != 0;
+					processCASbits($3, @3, "UNIQUE",
+								   &n->deferrable, &n->initdeferred, NULL,
+								   yyscanner);
 					$$ = (Node *)n;
 				}
 			| PRIMARY KEY '(' columnList ')' opt_definition OptConsTableSpace
@@ -2790,8 +2802,9 @@ ConstraintElem:
 					n->options = $6;
 					n->indexname = NULL;
 					n->indexspace = $7;
-					n->deferrable = ($8 & 1) != 0;
-					n->initdeferred = ($8 & 2) != 0;
+					processCASbits($8, @8, "PRIMARY KEY",
+								   &n->deferrable, &n->initdeferred, NULL,
+								   yyscanner);
 					$$ = (Node *)n;
 				}
 			| PRIMARY KEY ExistingIndex ConstraintAttributeSpec
@@ -2803,8 +2816,9 @@ ConstraintElem:
 					n->options = NIL;
 					n->indexname = $3;
 					n->indexspace = NULL;
-					n->deferrable = ($4 & 1) != 0;
-					n->initdeferred = ($4 & 2) != 0;
+					processCASbits($4, @4, "PRIMARY KEY",
+								   &n->deferrable, &n->initdeferred, NULL,
+								   yyscanner);
 					$$ = (Node *)n;
 				}
 			| EXCLUDE access_method_clause '(' ExclusionConstraintList ')'
@@ -2820,8 +2834,9 @@ ConstraintElem:
 					n->indexname		= NULL;
 					n->indexspace		= $7;
 					n->where_clause		= $8;
-					n->deferrable		= ($9 & 1) != 0;
-					n->initdeferred		= ($9 & 2) != 0;
+					processCASbits($9, @9, "EXCLUDE",
+								   &n->deferrable, &n->initdeferred, NULL,
+								   yyscanner);
 					$$ = (Node *)n;
 				}
 			| FOREIGN KEY '(' columnList ')' REFERENCES qualified_name
@@ -2836,27 +2851,11 @@ ConstraintElem:
 					n->fk_matchtype		= $9;
 					n->fk_upd_action	= (char) ($10 >> 8);
 					n->fk_del_action	= (char) ($10 & 0xFF);
-					n->deferrable		= ($11 & 1) != 0;
-					n->initdeferred		= ($11 & 2) != 0;
-					n->skip_validation  = false;
-					n->initially_valid  = true;
-					$$ = (Node *)n;
-				}
-			| FOREIGN KEY '(' columnList ')' REFERENCES qualified_name
-				opt_column_list key_match key_actions
-				NOT VALID
-				{
-					Constraint *n = makeNode(Constraint);
-					n->contype = CONSTR_FOREIGN;
-					n->location = @1;
-					n->pktable			= $7;
-					n->fk_attrs			= $4;
-					n->pk_attrs			= $8;
-					n->fk_matchtype		= $9;
-					n->fk_upd_action	= (char) ($10 >> 8);
-					n->fk_del_action	= (char) ($10 & 0xFF);
-					n->skip_validation  = true;
-					n->initially_valid  = false;
+					processCASbits($11, @11, "FOREIGN KEY",
+								   &n->deferrable, &n->initdeferred,
+								   &n->skip_validation,
+								   yyscanner);
+					n->initially_valid = !n->skip_validation;
 					$$ = (Node *)n;
 				}
 		;
@@ -4031,8 +4030,9 @@ CreateTrigStmt:
 					n->columns = (List *) lsecond($6);
 					n->whenClause = $14;
 					n->isconstraint  = TRUE;
-					n->deferrable = ($10 & 1) != 0;
-					n->initdeferred = ($10 & 2) != 0;
+					processCASbits($10, @10, "TRIGGER",
+								   &n->deferrable, &n->initdeferred, NULL,
+								   yyscanner);
 					n->constrrel = $9;
 					$$ = (Node *)n;
 				}
@@ -4135,45 +4135,40 @@ OptConstrFromTable:
 		;
 
 ConstraintAttributeSpec:
-			ConstraintDeferrabilitySpec
-				{ $$ = $1; }
-			| ConstraintDeferrabilitySpec ConstraintTimeSpec
+			/*EMPTY*/
+				{ $$ = 0; }
+			| ConstraintAttributeSpec ConstraintAttributeElem
 				{
-					if ($1 == 0 && $2 != 0)
+					/*
+					 * We must complain about conflicting options.
+					 * We could, but choose not to, complain about redundant
+					 * options (ie, where $2's bit is already set in $1).
+					 */
+					int		newspec = $1 | $2;
+
+					/* special message for this case */
+					if ((newspec & (CAS_NOT_DEFERRABLE | CAS_INITIALLY_DEFERRED)) == (CAS_NOT_DEFERRABLE | CAS_INITIALLY_DEFERRED))
 						ereport(ERROR,
 								(errcode(ERRCODE_SYNTAX_ERROR),
 								 errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE"),
-								 parser_errposition(@1)));
-					$$ = $1 | $2;
-				}
-			| ConstraintTimeSpec
-				{
-					if ($1 != 0)
-						$$ = 3;
-					else
-						$$ = 0;
-				}
-			| ConstraintTimeSpec ConstraintDeferrabilitySpec
-				{
-					if ($2 == 0 && $1 != 0)
+								 parser_errposition(@2)));
+					/* generic message for other conflicts */
+					if ((newspec & (CAS_NOT_DEFERRABLE | CAS_DEFERRABLE)) == (CAS_NOT_DEFERRABLE | CAS_DEFERRABLE) ||
+						(newspec & (CAS_INITIALLY_IMMEDIATE | CAS_INITIALLY_DEFERRED)) == (CAS_INITIALLY_IMMEDIATE | CAS_INITIALLY_DEFERRED))
 						ereport(ERROR,
 								(errcode(ERRCODE_SYNTAX_ERROR),
-								 errmsg("constraint declared INITIALLY DEFERRED must be DEFERRABLE"),
-								 parser_errposition(@1)));
-					$$ = $1 | $2;
+								 errmsg("conflicting constraint properties"),
+								 parser_errposition(@2)));
+					$$ = newspec;
 				}
-			| /*EMPTY*/
-				{ $$ = 0; }
 		;
 
-ConstraintDeferrabilitySpec:
-			NOT DEFERRABLE							{ $$ = 0; }
-			| DEFERRABLE							{ $$ = 1; }
-		;
-
-ConstraintTimeSpec:
-			INITIALLY IMMEDIATE						{ $$ = 0; }
-			| INITIALLY DEFERRED					{ $$ = 2; }
+ConstraintAttributeElem:
+			NOT DEFERRABLE					{ $$ = CAS_NOT_DEFERRABLE; }
+			| DEFERRABLE					{ $$ = CAS_DEFERRABLE; }
+			| INITIALLY IMMEDIATE			{ $$ = CAS_INITIALLY_IMMEDIATE; }
+			| INITIALLY DEFERRED			{ $$ = CAS_INITIALLY_DEFERRED; }
+			| NOT VALID						{ $$ = CAS_NOT_VALID; }
 		;
 
 
@@ -4217,8 +4212,9 @@ CreateAssertStmt:
 					n->trigname = $3;
 					n->args = list_make1($6);
 					n->isconstraint  = TRUE;
-					n->deferrable = ($8 & 1) != 0;
-					n->initdeferred = ($8 & 2) != 0;
+					processCASbits($8, @8, "ASSERTION",
+								   &n->deferrable, &n->initdeferred, NULL,
+								   yyscanner);
 
 					ereport(ERROR,
 							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
@@ -12865,6 +12861,64 @@ SplitColQualList(List *qualList,
 	*constraintList = qualList;
 }
 
+/*
+ * Process result of ConstraintAttributeSpec, and set appropriate bool flags
+ * in the output command node.  Pass NULL for any flags the particular
+ * command doesn't support.
+ */
+static void
+processCASbits(int cas_bits, int location, const char *constrType,
+			   bool *deferrable, bool *initdeferred, bool *not_valid,
+			   core_yyscan_t yyscanner)
+{
+	/* defaults */
+	if (deferrable)
+		*deferrable = false;
+	if (initdeferred)
+		*initdeferred = false;
+	if (not_valid)
+		*not_valid = false;
+
+	if (cas_bits & (CAS_DEFERRABLE | CAS_INITIALLY_DEFERRED))
+	{
+		if (deferrable)
+			*deferrable = true;
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 /* translator: %s is CHECK, UNIQUE, or similar */
+					 errmsg("%s constraints cannot be marked DEFERRABLE",
+							constrType),
+					 parser_errposition(location)));
+	}
+
+	if (cas_bits & CAS_INITIALLY_DEFERRED)
+	{
+		if (initdeferred)
+			*initdeferred = true;
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 /* translator: %s is CHECK, UNIQUE, or similar */
+					 errmsg("%s constraints cannot be marked DEFERRABLE",
+							constrType),
+					 parser_errposition(location)));
+	}
+
+	if (cas_bits & CAS_NOT_VALID)
+	{
+		if (not_valid)
+			*not_valid = true;
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 /* translator: %s is CHECK, UNIQUE, or similar */
+					 errmsg("%s constraints cannot be marked NOT VALID",
+							constrType),
+					 parser_errposition(location)));
+	}
+}
+
 /* parser_init()
  * Initialize to parse one query string
  */
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index 485bf4b8e7f..51899c6b5b4 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -1751,7 +1751,8 @@ transformFKConstraints(CreateStmtContext *cxt,
 
 	/*
 	 * If CREATE TABLE or adding a column with NULL default, we can safely
-	 * skip validation of the constraint.
+	 * skip validation of FK constraints, and nonetheless mark them valid.
+	 * (This will override any user-supplied NOT VALID flag.)
 	 */
 	if (skipValidation)
 	{