[llvm] [ADT] Use adl_begin in make_first_range and make_second_range (PR #130521)

[Jakub Kuderski via llvm-commits]

https://github.com/kuhar created https://github.com/llvm/llvm-project/pull/130521

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

This was a part of https://github.com/llvm/llvm-project/pull/87936 but reverted due to buildbot failures.

This PR is stacked on top of https://github.com/llvm/llvm-project/pull/130508.

>From 022fa8a4037f418e22649821839851811f262d9b 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 1/2] [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 fe1d010574e31..c367a21dfa0b9 100644
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -376,8 +376,7 @@ 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 e107cb570641b..cdda9bb1eefaf 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};
 

>From 01393783202f5e348c9b0131445fef5336b49a61 Mon Sep 17 00:00:00 2001
From: Jakub Kuderski <jakub at nod-labs.com>
Date: Sun, 9 Mar 2025 18:03:55 -0400
Subject: [PATCH 2/2] [ADT] Use `adl_begin` in `make_first_range` and
 `make_second_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.

This PR is stacked on top of #130508.
---
 llvm/include/llvm/ADT/STLExtras.h    |  4 ++--
 llvm/unittests/ADT/STLExtrasTest.cpp | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
index c367a21dfa0b9..8600c59d9306d 100644
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -1437,7 +1437,7 @@ template <typename EltTy, typename FirstTy> class first_or_second_type {
 
 /// Given a container of pairs, return a range over the first elements.
 template <typename ContainerTy> auto make_first_range(ContainerTy &&c) {
-  using EltTy = decltype((*std::begin(c)));
+  using EltTy = decltype(*adl_begin(c));
   return llvm::map_range(std::forward<ContainerTy>(c),
                          [](EltTy elt) -> typename detail::first_or_second_type<
                                            EltTy, decltype((elt.first))>::type {
@@ -1447,7 +1447,7 @@ template <typename ContainerTy> auto make_first_range(ContainerTy &&c) {
 
 /// Given a container of pairs, return a range over the second elements.
 template <typename ContainerTy> auto make_second_range(ContainerTy &&c) {
-  using EltTy = decltype((*std::begin(c)));
+  using EltTy = decltype(*adl_begin(c));
   return llvm::map_range(
       std::forward<ContainerTy>(c),
       [](EltTy elt) ->
diff --git a/llvm/unittests/ADT/STLExtrasTest.cpp b/llvm/unittests/ADT/STLExtrasTest.cpp
index cdda9bb1eefaf..6d1478a9102a6 100644
--- a/llvm/unittests/ADT/STLExtrasTest.cpp
+++ b/llvm/unittests/ADT/STLExtrasTest.cpp
@@ -421,6 +421,15 @@ void swap(some_struct &lhs, some_struct &rhs) {
   rhs.swap_val = "rhs";
 }
 
+struct Pairs {
+  std::vector<std::pair<std::string, int>> data;
+  using const_iterator =
+      std::vector<std::pair<std::string, int>>::const_iterator;
+};
+
+Pairs::const_iterator begin(const Pairs &p) { return p.data.begin(); }
+Pairs::const_iterator end(const Pairs &p) { return p.data.end(); }
+
 struct requires_move {};
 int *begin(requires_move &&) { return nullptr; }
 int *end(requires_move &&) { return nullptr; }
@@ -504,6 +513,15 @@ TEST(STLExtrasTest, ConcatRange) {
   EXPECT_EQ(Expected, Test);
 }
 
+TEST(STLExtrasTest, MakeFirstSecondRangeADL) {
+  // Make sure that we use the `begin`/`end` functions from `some_namespace`,
+  // using ADL.
+  some_namespace::Pairs Pairs;
+  Pairs.data = {{"foo", 1}, {"bar", 2}};
+  EXPECT_THAT(make_first_range(Pairs), ElementsAre("foo", "bar"));
+  EXPECT_THAT(make_second_range(Pairs), ElementsAre(1, 2));
+}
+
 template <typename T> struct Iterator {
   int i = 0;
   T operator*() const { return i; }