commit 1af214dea2172dccbb43bad6c62f1275e8b29e97
author Wyatt Hepler <hepler@google.com> Wed Jan 19 10:42:47 2022 -0800
committer CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Jan 19 19:34:44 2022 +0000
tree 66743b6482a450f0485ecbdb975b0a4765314ea7
parent 1efc17b5264a19b7aa8cbe4e3e7dfc5d1abcbe1a

pw_function: Fix for move-only types

- Add std::forward to support move-only function arguments.
- Mark default constructors constexpr.

Change-Id: I505ae0a40919b61ad7be927d19273ab22354f568
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/79501
Pigweed-Auto-Submit: Wyatt Hepler <hepler@google.com>
Reviewed-by: Alexei Frolov <frolv@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>

pw_function/function_test.cc

diff --git a/pw_function/function_test.cc b/pw_function/function_test.cc
index 0c2b89a..541a4c7 100644
--- a/pw_function/function_test.cc
+++ b/pw_function/function_test.cc
@@ -247,6 +247,28 @@
 #endif  // __clang_analyzer__
 }
 
+TEST(Function, MoveOnlyType) {
+  class MoveOnlyType {
+   public:
+    MoveOnlyType() = default;
+
+    MoveOnlyType(const MoveOnlyType& other) = delete;
+    MoveOnlyType& operator=(const MoveOnlyType& other) = delete;
+
+    MoveOnlyType(MoveOnlyType&&) = default;
+    MoveOnlyType& operator=(MoveOnlyType&&) = default;
+
+    bool ItsWorking() const { return true; }
+  };
+
+  pw::Function<bool(MoveOnlyType)> function = [](MoveOnlyType value) {
+    return value.ItsWorking();
+  };
+
+  MoveOnlyType move_only;
+  EXPECT_TRUE(function(std::move(move_only)));
+}
+
 }  // namespace
 }  // namespace pw
 

pw_function/public/pw_function/internal/function.h

diff --git a/pw_function/public/pw_function/internal/function.h b/pw_function/public/pw_function/internal/function.h
index de96845..8cffd02 100644
--- a/pw_function/public/pw_function/internal/function.h
+++ b/pw_function/public/pw_function/internal/function.h
@@ -55,7 +55,7 @@
 // call operator, which is templated on the function arguments and return type.
 class GenericFunctionTarget {
  public:
-  GenericFunctionTarget() = default;
+  constexpr GenericFunctionTarget() = default;
 
   GenericFunctionTarget(const GenericFunctionTarget&) = delete;
   GenericFunctionTarget(GenericFunctionTarget&&) = delete;
@@ -79,7 +79,7 @@
 template <typename Return, typename... Args>
 class FunctionTarget : public GenericFunctionTarget {
  public:
-  FunctionTarget() = default;
+  constexpr FunctionTarget() = default;
 
   // Invoke the callable stored by the function target.
   virtual Return operator()(Args... args) const = 0;
@@ -122,7 +122,9 @@
       : callable_(std::move(other.callable_)) {}
   InlineFunctionTarget& operator=(InlineFunctionTarget&&) = default;
 
-  Return operator()(Args... args) const final { return callable_(args...); }
+  Return operator()(Args... args) const final {
+    return callable_(std::forward<Args>(args)...);
+  }
 
   void MoveInitializeTo(void* ptr) final {
     new (ptr) InlineFunctionTarget(std::move(*this));