commit 49c1f36ec50b3f812f9031d1cf35f1f514eb2a21
author Abseil Team <absl-team@google.com> Fri May 24 14:10:10 2024 -0700
committer Copybara-Service <copybara-worker@google.com> Fri May 24 14:11:02 2024 -0700
tree e2b813947b2519536c50c00992b84bc282b51ae1
parent f858e740085e4ec59c319bb1a4237b628bcad4a8

overload: make the constructor constexpr

PiperOrigin-RevId: 637029703
Change-Id: I58b4c3a3f1aab3062b51d15c5b9fecfd3ca3193a

absl/functional/overload.h

diff --git a/absl/functional/overload.h b/absl/functional/overload.h
index 34ffa68..7e19e70 100644
--- a/absl/functional/overload.h
+++ b/absl/functional/overload.h
@@ -62,7 +62,7 @@
   // aggregate initialization. Before then we must provide a constructor that
   // makes this work.
   //
-  explicit Overload(T... ts) : T(std::move(ts))... {}
+  constexpr explicit Overload(T... ts) : T(std::move(ts))... {}
 };
 
 // Before C++20, which added support for CTAD for aggregate types, we must also

absl/functional/overload_test.cc

diff --git a/absl/functional/overload_test.cc b/absl/functional/overload_test.cc
index 92f0eb9..fa49d29 100644
--- a/absl/functional/overload_test.cc
+++ b/absl/functional/overload_test.cc
@@ -194,6 +194,20 @@
   EXPECT_EQ(5, absl::visit(overloaded, v));
 }
 
+TEST(OverloadTest, HasConstexprConstructor) {
+  constexpr auto overloaded = absl::Overload{
+      [](int v) { return absl::StrCat("int ", v); },
+      [](double v) { return absl::StrCat("double ", v); },
+      [](const char* v) { return absl::StrCat("const char* ", v); },
+      [](auto v) { return absl::StrCat("auto ", v); },
+  };
+
+  EXPECT_EQ("int 1", overloaded(1));
+  EXPECT_EQ("double 2.5", overloaded(2.5));
+  EXPECT_EQ("const char* hello", overloaded("hello"));
+  EXPECT_EQ("auto 1.5", overloaded(1.5f));
+}
+
 }  // namespace
 
 #endif