Fix flattening of serde_json::Value

It should behave similarly to flattening a `Map<String,Value>` in that it allows any properties

schemars/src/_private.rs

@@ -176,7 +176,15 @@ pub fn apply_inner_validation(schema: &mut Schema, f: fn(&mut Schema) -> ()) {
 }
 
 pub fn flatten(schema: &mut Schema, other: Schema) {
-    if let Value::Object(obj2) = other.to_value() {
+    match other.try_to_object() {
+        Err(false) => {}
+        Err(true) => {
+            schema
+                .ensure_object()
+                .entry("additionalProperties")
+                .or_insert(true.into());
+        }
+        Ok(obj2) => {
             let obj1 = schema.ensure_object();
 
             for (key, value2) in obj2 {
@@ -184,32 +192,8 @@ pub fn flatten(schema: &mut Schema, other: Schema) {
                     Entry::Vacant(vacant) => {
                         vacant.insert(value2);
                     }
-                Entry::Occupied(mut occupied) => {
+                    Entry::Occupied(occupied) => {
                         match occupied.key().as_str() {
-                        // This special "type" handling can probably be removed once the enum variant `with`/`schema_with` behaviour is fixed
-                        "type" => match (occupied.get_mut(), value2) {
-                            (Value::Array(a1), Value::Array(mut a2)) => {
-                                a2.retain(|v2| !a1.contains(v2));
-                                a1.extend(a2);
-                            }
-                            (v1, Value::Array(mut a2)) => {
-                                if !a2.contains(v1) {
-                                    a2.push(std::mem::take(v1));
-                                    *occupied.get_mut() = Value::Array(a2);
-                                }
-                            }
-                            (Value::Array(a1), v2) => {
-                                if !a1.contains(&v2) {
-                                    a1.push(v2);
-                                }
-                            }
-                            (v1, v2) => {
-                                if v1 != &v2 {
-                                    *occupied.get_mut() =
-                                        Value::Array(vec![std::mem::take(v1), v2]);
-                                }
-                            }
-                        },
                             "required" => {
                                 if let Value::Array(a1) = occupied.into_mut() {
                                     if let Value::Array(a2) = value2 {
@@ -233,3 +217,4 @@ pub fn flatten(schema: &mut Schema, other: Schema) {
             }
         }
     }
+}

schemars/tests/expected/flattened_value.json

@@ -0,0 +1,14 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "title": "FlattenValue",
+  "type": "object",
+  "properties": {
+    "flag": {
+      "type": "boolean"
+    }
+  },
+  "required": [
+    "flag"
+  ],
+  "additionalProperties": true
+}

schemars/tests/flatten.rs

@@ -1,5 +1,7 @@
 mod util;
 use schemars::JsonSchema;
+use serde_json::Value;
+use std::collections::BTreeMap;
 use util::*;
 
 #[allow(dead_code)]
@@ -53,5 +55,34 @@ fn test_flat_schema() -> TestResult {
 
 #[test]
 fn test_flattened_schema() -> TestResult {
+    // intentionally using the same file as test_flat_schema, as the schema should be identical
     test_default_generated_schema::<Deep1>("flatten")
 }
+
+#[allow(dead_code)]
+#[derive(JsonSchema)]
+struct FlattenValue {
+    flag: bool,
+    #[serde(flatten)]
+    value: Value,
+}
+
+#[allow(dead_code)]
+#[derive(JsonSchema)]
+#[schemars(rename = "FlattenValue")]
+struct FlattenMap {
+    flag: bool,
+    #[serde(flatten)]
+    value: BTreeMap<String, Value>,
+}
+
+#[test]
+fn test_flattened_value() -> TestResult {
+    test_default_generated_schema::<FlattenValue>("flattened_value")
+}
+
+#[test]
+fn test_flattened_map() -> TestResult {
+    // intentionally using the same file as test_flattened_value, as the schema should be identical
+    test_default_generated_schema::<FlattenMap>("flattened_value")
+}