[llvm] d9f309c - Reland "[ADT] Relax type requirements for `is_contained`"

[Jakub Kuderski via llvm-commits]

Author: Jakub Kuderski
Date: 2023-02-21T14:36:58-05:00
New Revision: d9f309c5c5d4bcb7b32bb57628e0c556d8556041

URL: https://github.com/llvm/llvm-project/commit/d9f309c5c5d4bcb7b32bb57628e0c556d8556041
DIFF: https://github.com/llvm/llvm-project/commit/d9f309c5c5d4bcb7b32bb57628e0c556d8556041.diff

LOG: Reland "[ADT] Relax type requirements for `is_contained`"

Added: 
    

Modified: 
    llvm/include/llvm/ADT/STLExtras.h
    llvm/unittests/ADT/STLExtrasTest.cpp

Removed: 
    


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diff  --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
index a8c54e0d9745..8702024d73d5 100644
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -1870,11 +1870,13 @@ bool is_contained(R &&Range, const E &Element) {
   return std::find(adl_begin(Range), adl_end(Range), Element) != adl_end(Range);
 }
 
-template <typename T>
-constexpr bool is_contained(std::initializer_list<T> Set, T Value) {
+/// Returns true iff \p Element exists in \p Set. This overload takes \p Set as
+/// an initializer list and is `constexpr`-friendly.
+template <typename T, typename E>
+constexpr bool is_contained(std::initializer_list<T> Set, const E &Element) {
   // TODO: Use std::find when we switch to C++20.
-  for (T V : Set)
-    if (V == Value)
+  for (const T &V : Set)
+    if (V == Element)
       return true;
   return false;
 }

diff  --git a/llvm/unittests/ADT/STLExtrasTest.cpp b/llvm/unittests/ADT/STLExtrasTest.cpp
index 992c51790c44..948cbaed16c0 100644
--- a/llvm/unittests/ADT/STLExtrasTest.cpp
+++ b/llvm/unittests/ADT/STLExtrasTest.cpp
@@ -960,11 +960,29 @@ enum Doggos {
   Longboi,
 };
 
+struct WooferCmp {
+  // Not copyable.
+  WooferCmp() = default;
+  WooferCmp(const WooferCmp &) = delete;
+  WooferCmp &operator=(const WooferCmp &) = delete;
+
+  friend bool operator==(const Doggos &Doggo, const WooferCmp &) {
+    return Doggo == Doggos::Woofer;
+  }
+};
+
 TEST(STLExtrasTest, IsContainedInitializerList) {
   EXPECT_TRUE(is_contained({Woofer, SubWoofer}, Woofer));
   EXPECT_TRUE(is_contained({Woofer, SubWoofer}, SubWoofer));
   EXPECT_FALSE(is_contained({Woofer, SubWoofer}, Pupper));
-  EXPECT_FALSE(is_contained({}, Longboi));
+
+  // Check that the initializer list type and the element type do not have to
+  // match exactly.
+  EXPECT_TRUE(is_contained({Floofer, Woofer, SubWoofer}, WooferCmp{}));
+  EXPECT_FALSE(is_contained({Floofer, SubWoofer}, WooferCmp{}));
+
+  EXPECT_TRUE(is_contained({"a", "bb", "ccc", "dddd"}, llvm::StringRef("ccc")));
+  EXPECT_FALSE(is_contained({"a", "bb", "ccc", "dddd"}, llvm::StringRef("x")));
 
   static_assert(is_contained({Woofer, SubWoofer}, SubWoofer), "SubWoofer!");
   static_assert(!is_contained({Woofer, SubWoofer}, Pupper), "Missing Pupper!");