RCORE-1994 Fix passing a double as argument to query on Decimal128

CHANGELOG.md

@@ -9,6 +9,7 @@
 * Fix a performance regression when reading values from Bson containers and revert some breaking changes to the Bson API ([PR #7377](https://github.com/realm/realm-core/pull/7377), since v14.0.0)
 * List KVO information was being populated for non-list collections ([PR #7378](https://github.com/realm/realm-core/pull/7378), since v14.0.0)
 * Setting a Mixed property to an ObjLink equal to its existing value would remove the existing backlinks and then exit before re-adding them, resulting in later assertion failures due to the backlink state being invalid ([PR #7384](https://github.com/realm/realm-core/pull/7384), since v14.0.0).
+* Passing a double as argument for a Query on Decimal128 did not work ([#7386](https://github.com/realm/realm-core/issues/7386), since v14.0.0)
 * Opening file with file format 23 in read-only mode will crash ([#7388](https://github.com/realm/realm-core/issues/7388), since v14.0.0)
 * Querying a dictionary over a link would sometimes result in out-of-bounds memory reads ([PR #7382](https://github.com/realm/realm-core/pull/7382), since v14.0.0).
 

src/realm/parser/driver.cpp

@@ -1407,9 +1407,12 @@ std::unique_ptr<Subexpr> ConstantNode::visit(ParserDriver* drv, DataType hint)
                 case type_Float:
                     ret = std::make_unique<Value<float>>(float(double_val));
                     break;
-                case type_Decimal:
-                    ret = std::make_unique<Value<Decimal128>>(Decimal128(text));
+                case type_Decimal: {
+                    // If not argument, try decode again to get full precision
+                    Decimal128 dec = (type == Type::ARG) ? Decimal128(double_val) : Decimal128(text);
+                    ret = std::make_unique<Value<Decimal128>>(dec);
                     break;
+                }
                 case type_Int: {
                     int64_t int_val = int64_t(double_val);
                     // Only return an integer if it precisely represents val

test/test_parser.cpp

@@ -4675,10 +4675,11 @@ TEST(Parser_Decimal128)
     verify_query(test_context, table, "dec >= -infinity", table->size() - num_nans);
 
     // argument substitution checks
-    std::any args[] = {Decimal128("0"), Decimal128("123"), realm::null{}};
-    size_t num_args = 3;
+    std::any args[] = {Decimal128("0"), Decimal128("123"), realm::null{}, 123.0};
+    size_t num_args = 4;
     verify_query_sub(test_context, table, "dec == $0", args, num_args, 1);
     verify_query_sub(test_context, table, "dec == $1", args, num_args, 1);
+    verify_query_sub(test_context, table, "dec == $3", args, num_args, 1);
     verify_query_sub(test_context, table, "dec == $2", args, num_args, 0);
     verify_query_sub(test_context, table, "nullable_dec == $2", args, num_args, 1);