[llvm] [ADT] Add `SmallVector::assign` overload for `ArrayRef` (PR #164680)

[Jakub Kuderski via llvm-commits]

https://github.com/kuhar updated https://github.com/llvm/llvm-project/pull/164680

>From d3ec7c8006c3777f91c5cf15c46014b2329b811e Mon Sep 17 00:00:00 2001
From: Jakub Kuderski <jakub at nod-labs.com>
Date: Wed, 22 Oct 2025 14:33:15 -0400
Subject: [PATCH] [ADT] Add SmallVector::assign overload for ArrayRef

We already have a matching constructor from ArrayRef, so add support for
assigning from ArrayRef as well.
---
 llvm/include/llvm/ADT/SmallVector.h    | 8 +++++++-
 llvm/unittests/ADT/SmallVectorTest.cpp | 9 +++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/llvm/include/llvm/ADT/SmallVector.h b/llvm/include/llvm/ADT/SmallVector.h
index efae6f339f9de..ca0b918f56c46 100644
--- a/llvm/include/llvm/ADT/SmallVector.h
+++ b/llvm/include/llvm/ADT/SmallVector.h
@@ -734,6 +734,12 @@ class SmallVectorImpl : public SmallVectorTemplateBase<T> {
 
   void assign(const SmallVectorImpl &RHS) { assign(RHS.begin(), RHS.end()); }
 
+  template <typename U,
+            typename = std::enable_if_t<std::is_convertible_v<U, T>>>
+  void assign(ArrayRef<U> AR) {
+    assign(AR.begin(), AR.end());
+  }
+
   iterator erase(const_iterator CI) {
     // Just cast away constness because this is a non-const member function.
     iterator I = const_cast<iterator>(CI);
@@ -1228,7 +1234,7 @@ class LLVM_GSL_OWNER SmallVector : public SmallVectorImpl<T>,
   }
 
   template <typename U,
-            typename = std::enable_if_t<std::is_convertible<U, T>::value>>
+            typename = std::enable_if_t<std::is_convertible_v<U, T>>>
   explicit SmallVector(ArrayRef<U> A) : SmallVectorImpl<T>(N) {
     this->append(A.begin(), A.end());
   }
diff --git a/llvm/unittests/ADT/SmallVectorTest.cpp b/llvm/unittests/ADT/SmallVectorTest.cpp
index e2e778f44b5e9..b216359ffd31c 100644
--- a/llvm/unittests/ADT/SmallVectorTest.cpp
+++ b/llvm/unittests/ADT/SmallVectorTest.cpp
@@ -599,6 +599,15 @@ TYPED_TEST(SmallVectorTest, AssignSmallVector) {
   assertValuesInOrder(V, 2u, 7, 7);
 }
 
+TYPED_TEST(SmallVectorTest, AssignArrayRef) {
+  SCOPED_TRACE("AssignArrayRef");
+  auto &V = this->theVector;
+  Constructable Other[] = {7, 8, 9};
+  V.push_back(Constructable(1));
+  V.assign(ArrayRef(Other));
+  assertValuesInOrder(V, 3u, 7, 8, 9);
+}
+
 // Move-assign test
 TYPED_TEST(SmallVectorTest, MoveAssignTest) {
   SCOPED_TRACE("MoveAssignTest");