Add cast to null when no way to cast

open-gpdb · Nov 21, 2024 · 389ef57 · 389ef57
1 parent cec2995
commit 389ef57
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diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
@@ -1341,6 +1341,12 @@ build_coercion_expression(Node *node,
 
 		return (Node *) iocoerce;
 	}
+	else if (pathtype == COERCION_PATH_NONE_SAFE) {
+		Const *nullconst = makeNullConst(targetTypeId, targetTypMod, InvalidOid);
+		nullconst->location = location;
+
+		return (Node *) nullconst;
+	}
 	else
 	{
 		elog(ERROR, "unsupported pathtype %d in build_coercion_expression",
@@ -2700,6 +2706,8 @@ find_coercion_pathway(Oid targetTypeId, Oid sourceTypeId,
 			else if (ccontext >= COERCION_EXPLICIT &&
 					 TypeCategory(sourceTypeId) == TYPCATEGORY_STRING)
 				result = COERCION_PATH_COERCEVIAIO;
+			else if (ccontext == COERCION_EXPLICIT_SAFE)
+				result = COERCION_PATH_NONE_SAFE;
 		}
 	}
 

diff --git a/src/include/parser/parse_coerce.h b/src/include/parser/parse_coerce.h
@@ -24,6 +24,7 @@ typedef char TYPCATEGORY;
 typedef enum CoercionPathType
 {
 	COERCION_PATH_NONE,			/* failed to find any coercion pathway */
+	COERCION_PATH_NONE_SAFE,	/* failed to find any coercion pathway, but */
 	COERCION_PATH_FUNC,			/* apply the specified coercion function */
 	COERCION_PATH_FUNC_SAFE,			/* apply the specified coercion function safe */
 	COERCION_PATH_RELABELTYPE,	/* binary-compatible cast, no function */