From 4549d9da3e85c96a71a7cf56de5e203b22801bfb Mon Sep 17 00:00:00 2001
From: Brendan Dahl <brendan.dahl@gmail.com>
Date: Fri, 10 Jun 2022 09:02:08 -0700
Subject: [PATCH] Add support for noexcept keyword to embind.  (#17140)

* Add support for noexcept keyword in C++ class methods

* Remove code duplication after adding support for noexcept

* Add support for noexcept keyword to embind.

This continues the work from #15273 and #10613 which supports the noexcept
keyword by ignoring it on c++17 compilers. I've also added a missing
template for class methods and tests for each possible use of noexcept.

Co-authored-by: Hunter Richards <hunter.a.richards@gmail.com>
---
 system/include/emscripten/bind.h | 30 ++++++++++++++++++++++++++++++
 tests/embind/embind_test.cpp     | 22 ++++++++++++++++++++++
 tests/test_other.py              |  2 ++
 3 files changed, 54 insertions(+)

diff --git a/system/include/emscripten/bind.h b/system/include/emscripten/bind.h
index 633652a7e3a4d..755e2645aa79e 100644
--- a/system/include/emscripten/bind.h
+++ b/system/include/emscripten/bind.h
@@ -635,6 +635,12 @@ struct GetterPolicy<GetterReturnType (GetterThisType::*)() const> {
     }
 };
 
+#ifdef __cpp_noexcept_function_type
+template<typename GetterReturnType, typename GetterThisType>
+struct GetterPolicy<GetterReturnType (GetterThisType::*)() const noexcept>
+     : GetterPolicy<GetterReturnType (GetterThisType::*)() const> {};
+#endif
+
 template<typename GetterReturnType, typename GetterThisType>
 struct GetterPolicy<GetterReturnType (*)(const GetterThisType&)> {
     typedef GetterReturnType ReturnType;
@@ -710,6 +716,12 @@ struct SetterPolicy<SetterReturnType (SetterThisType::*)(SetterArgumentType)> {
     }
 };
 
+#ifdef __cpp_noexcept_function_type
+template<typename SetterReturnType, typename SetterThisType, typename SetterArgumentType>
+struct SetterPolicy<SetterReturnType (SetterThisType::*)(SetterArgumentType) noexcept>
+     : SetterPolicy<SetterReturnType (SetterThisType::*)(SetterArgumentType)> {};
+#endif
+
 template<typename SetterReturnType, typename SetterThisType, typename SetterArgumentType>
 struct SetterPolicy<SetterReturnType (*)(SetterThisType&, SetterArgumentType)> {
     typedef SetterArgumentType ArgumentType;
@@ -1326,6 +1338,12 @@ struct RegisterClassMethod<ReturnType (ClassType::*)(Args...)> {
     }
 };
 
+#ifdef __cpp_noexcept_function_type
+template<typename ClassType, typename ReturnType, typename... Args>
+struct RegisterClassMethod<ReturnType (ClassType::*)(Args...) noexcept>
+     : RegisterClassMethod<ReturnType (ClassType::*)(Args...)> {};
+#endif
+
 template<typename ClassType, typename ReturnType, typename... Args>
 struct RegisterClassMethod<ReturnType (ClassType::*)(Args...) const> {
 
@@ -1347,6 +1365,12 @@ struct RegisterClassMethod<ReturnType (ClassType::*)(Args...) const> {
     }
 };
 
+#ifdef __cpp_noexcept_function_type
+template<typename ClassType, typename ReturnType, typename... Args>
+struct RegisterClassMethod<ReturnType (ClassType::*)(Args...) const noexcept>
+     : RegisterClassMethod<ReturnType (ClassType::*)(Args...) const> {};
+#endif
+
 template<typename ReturnType, typename ThisType, typename... Args>
 struct RegisterClassMethod<ReturnType (*)(ThisType, Args...)> {
 
@@ -1367,6 +1391,12 @@ struct RegisterClassMethod<ReturnType (*)(ThisType, Args...)> {
     }
 };
 
+#ifdef __cpp_noexcept_function_type
+template<typename ReturnType, typename ThisType, typename... Args>
+struct RegisterClassMethod<ReturnType (*)(ThisType, Args...) noexcept>
+     : RegisterClassMethod<ReturnType (*)(ThisType, Args...)> {};
+#endif
+
 template<typename ReturnType, typename ThisType, typename... Args>
 struct RegisterClassMethod<std::function<ReturnType (ThisType, Args...)>> {
 
diff --git a/tests/embind/embind_test.cpp b/tests/embind/embind_test.cpp
index a20d596666bc2..6b21ac7c2a2dc 100644
--- a/tests/embind/embind_test.cpp
+++ b/tests/embind/embind_test.cpp
@@ -386,6 +386,22 @@ class BigClass {
     }
 };
 
+class NoExceptClass {
+public:
+    int getValue() noexcept {
+        return 42;
+    }
+    int getValueConst() const noexcept {
+        return 43;
+    }
+    int getX() const noexcept { return x; }
+    void setX(int x_) noexcept { x = x_; }
+private:
+    int x;
+};
+
+void embind_test_no_except_function(NoExceptClass&) noexcept {}
+
 class ParentClass {
 public:
     ParentClass(): bigClass() {};
@@ -1970,6 +1986,12 @@ EMSCRIPTEN_BINDINGS(tests) {
         .function("getMember", &TemplateClass<int>::getMember)
         ;
 
+    class_<NoExceptClass>("NoExceptClass")
+        .function("embind_test_no_except_function", &embind_test_no_except_function)
+        .function("getValue", &NoExceptClass::getValue)
+        .function("getValueConst", &NoExceptClass::getValueConst)
+        .property("x", &NoExceptClass::getX, &NoExceptClass::setX);
+
     class_<ContainsTemplatedMemberClass>("ContainsTemplatedMemberClass")
         .constructor<>()
         .function("getTestTemplate", &ContainsTemplatedMemberClass::getTestTemplate)
diff --git a/tests/test_other.py b/tests/test_other.py
index d97981f424747..049dc2e4c8d4d 100644
--- a/tests/test_other.py
+++ b/tests/test_other.py
@@ -2499,6 +2499,8 @@ def test_embind_closure_no_dynamic_execution(self):
   def test_embind(self, extra_args):
     test_cases = [
       (['-lembind']),
+      # Ensure embind compiles under C++17 where "noexcept" became part of the function signature.
+      (['-lembind', '-std=c++17']),
       (['-lembind', '-O1']),
       (['-lembind', '-O2']),
       (['-lembind', '-O2', '-sALLOW_MEMORY_GROWTH', test_file('embind/isMemoryGrowthEnabled=true.cpp')]),