[llvm] [ADT] Use `adl_being`/`end` in `map_range` (PR #130508)

[Jakub Kuderski via llvm-commits]

https://github.com/kuhar created https://github.com/llvm/llvm-project/pull/130508

This is to make sure that ADT helpers consistently use argument dependent lookup when dealing with input ranges.

This was a part of #87936 but reverted due to buildbot failures.

Also add `map_range` unit tests -- there were no pre-existing tests AFAICT.

>From da5317acabf94e5c3c9579c222ce742a8d996c40 Mon Sep 17 00:00:00 2001
From: Jakub Kuderski <jakub at nod-labs.com>
Date: Sun, 9 Mar 2025 15:56:41 -0400
Subject: [PATCH] [ADT] Use `adl_being`/`end` in `map_range`

This is to make sure that ADT helpers consistently use argument
dependent lookup when dealing with input ranges.

This was a part of #87936 but reverted due to buildbot failures.
---
 llvm/include/llvm/ADT/STLExtras.h    |  3 +--
 llvm/unittests/ADT/STLExtrasTest.cpp | 12 ++++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
index ace5f60b572d7..97e41cc27e0a9 100644
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -375,8 +375,7 @@ inline mapped_iterator<ItTy, FuncTy> map_iterator(ItTy I, FuncTy F) {
 
 template <class ContainerTy, class FuncTy>
 auto map_range(ContainerTy &&C, FuncTy F) {
-  return make_range(map_iterator(std::begin(C), F),
-                    map_iterator(std::end(C), F));
+  return make_range(map_iterator(adl_begin(C), F), map_iterator(adl_end(C), F));
 }
 
 /// A base type of mapped iterator, that is useful for building derived
diff --git a/llvm/unittests/ADT/STLExtrasTest.cpp b/llvm/unittests/ADT/STLExtrasTest.cpp
index 406ff2bc16073..5b1f4cdd7bdaf 100644
--- a/llvm/unittests/ADT/STLExtrasTest.cpp
+++ b/llvm/unittests/ADT/STLExtrasTest.cpp
@@ -730,6 +730,18 @@ TEST(STLExtrasTest, DropEndDefaultTest) {
   EXPECT_EQ(i, 4);
 }
 
+TEST(STLExtrasTest, MapRangeTest) {
+  SmallVector<int, 5> Vec{0, 1, 2};
+  EXPECT_THAT(map_range(Vec, [](int V) { return V + 1; }),
+              ElementsAre(1, 2, 3));
+
+  // Make sure that we use the `begin`/`end` functions
+  // from `some_namespace`, using ADL.
+  some_namespace::some_struct S;
+  S.data = {3, 4, 5};
+  EXPECT_THAT(map_range(S, [](int V) { return V * 2; }), ElementsAre(6, 8, 10));
+}
+
 TEST(STLExtrasTest, EarlyIncrementTest) {
   std::list<int> L = {1, 2, 3, 4};