[embind] Fix custom registered types used with field bindings. (#21949)

* fix friend declaration in val.h

The code as it was trying to declare a template instantiation as a friend, and then specialize it later, which caused a build break. This fix just declares the whole template as a friend.

* [embind] Add test for custom registered types used with field bindings.

---------

Co-authored-by: walkingeyerobot <[email protected]>

Author: brendandahl

system/include/emscripten/val.h

@@ -676,7 +676,8 @@ class val {
   pthread_t thread;
   EM_VAL handle;
 
-  friend struct internal::BindingType<val>;
+  template <typename T, typename>
+  friend struct ::emscripten::internal::BindingType;
 };
 
 struct val::iterator {

test/other/embind_tsgen.cpp

@@ -52,9 +52,13 @@ struct ValArr {
   int x, y, z;
 };
 
+EMSCRIPTEN_DECLARE_VAL_TYPE(CallbackType);
+
 struct ValObj {
   Foo foo;
   Bar bar;
+  CallbackType callback;
+  ValObj() : callback(val::undefined()) {}
 };
 
 class ClassWithConstructor {
@@ -81,8 +85,6 @@ int smart_ptr_function(std::shared_ptr<ClassWithSmartPtrConstructor>) {
   return 0;
 }
 
-EMSCRIPTEN_DECLARE_VAL_TYPE(CallbackType);
-
 int function_with_callback_param(CallbackType ct) {
   ct(val("hello"));
   return 0;
@@ -165,7 +167,8 @@ EMSCRIPTEN_BINDINGS(Test) {
 
   value_object<ValObj>("ValObj")
       .field("foo", &ValObj::foo)
-      .field("bar", &ValObj::bar);
+      .field("bar", &ValObj::bar)
+      .field("callback", &ValObj::callback);
 
   register_vector<int>("IntVec");
 

test/other/embind_tsgen.d.ts

@@ -65,11 +65,6 @@ export interface Foo {
   delete(): void;
 }
 
-export type ValObj = {
-  foo: Foo,
-  bar: Bar
-};
-
 export interface ClassWithConstructor {
   fn(_0: number): number;
   delete(): void;
@@ -84,6 +79,12 @@ export interface ClassWithSmartPtrConstructor {
   delete(): void;
 }
 
+export type ValObj = {
+  foo: Foo,
+  bar: Bar,
+  callback: (message: string) => void
+};
+
 export interface BaseClass {
   fn(_0: number): number;
   delete(): void;

test/other/embind_tsgen_ignore_1.d.ts

@@ -74,11 +74,6 @@ export interface Foo {
   delete(): void;
 }
 
-export type ValObj = {
-  foo: Foo,
-  bar: Bar
-};
-
 export interface ClassWithConstructor {
   fn(_0: number): number;
   delete(): void;
@@ -93,6 +88,12 @@ export interface ClassWithSmartPtrConstructor {
   delete(): void;
 }
 
+export type ValObj = {
+  foo: Foo,
+  bar: Bar,
+  callback: (message: string) => void
+};
+
 export interface BaseClass {
   fn(_0: number): number;
   delete(): void;

test/other/embind_tsgen_ignore_2.d.ts

@@ -51,11 +51,6 @@ export interface Foo {
   delete(): void;
 }
 
-export type ValObj = {
-  foo: Foo,
-  bar: Bar
-};
-
 export interface ClassWithConstructor {
   fn(_0: number): number;
   delete(): void;
@@ -70,6 +65,12 @@ export interface ClassWithSmartPtrConstructor {
   delete(): void;
 }
 
+export type ValObj = {
+  foo: Foo,
+  bar: Bar,
+  callback: (message: string) => void
+};
+
 export interface BaseClass {
   fn(_0: number): number;
   delete(): void;

test/other/embind_tsgen_ignore_3.d.ts

@@ -65,11 +65,6 @@ export interface Foo {
   delete(): void;
 }
 
-export type ValObj = {
-  foo: Foo,
-  bar: Bar
-};
-
 export interface ClassWithConstructor {
   fn(_0: number): number;
   delete(): void;
@@ -84,6 +79,12 @@ export interface ClassWithSmartPtrConstructor {
   delete(): void;
 }
 
+export type ValObj = {
+  foo: Foo,
+  bar: Bar,
+  callback: (message: string) => void
+};
+
 export interface BaseClass {
   fn(_0: number): number;
   delete(): void;