[llvm][ADT] Use ADL to find begin()/end() in interleave*

llvm/include/llvm/ADT/STLExtras.h

@@ -2151,15 +2151,15 @@ template <typename Container, typename UnaryFunctor, typename NullaryFunctor,
               !std::is_constructible<StringRef, NullaryFunctor>::value>>
 inline void interleave(const Container &c, UnaryFunctor each_fn,
                        NullaryFunctor between_fn) {
-  interleave(c.begin(), c.end(), each_fn, between_fn);
+  interleave(adl_begin(c), adl_end(c), each_fn, between_fn);
 }
 
 /// Overload of interleave for the common case of string separator.
 template <typename Container, typename UnaryFunctor, typename StreamT,
           typename T = detail::ValueOfRange<Container>>
 inline void interleave(const Container &c, StreamT &os, UnaryFunctor each_fn,
                        const StringRef &separator) {
-  interleave(c.begin(), c.end(), each_fn, [&] { os << separator; });
+  interleave(adl_begin(c), adl_end(c), each_fn, [&] { os << separator; });
 }
 template <typename Container, typename StreamT,
           typename T = detail::ValueOfRange<Container>>

llvm/unittests/ADT/CMakeLists.txt

@@ -44,6 +44,7 @@ add_llvm_unittest(ADTTests
   ImmutableMapTest.cpp
   ImmutableSetTest.cpp
   IntEqClassesTest.cpp
+  Interleave.cpp
   IntervalMapTest.cpp
   IntervalTreeTest.cpp
   IntrusiveRefCntPtrTest.cpp

llvm/unittests/ADT/Interleave.cpp

@@ -0,0 +1,42 @@
+//===- unittests/ADT/Interleave.cpp - Interleave unit tests ---------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/raw_ostream.h"
+
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+
+TEST(InterleaveTest, Interleave) {
+  std::string Str;
+  raw_string_ostream OS(Str);
+
+  // Check that interleave works on a SmallVector.
+  SmallVector<const char *> Doodles = {"golden", "berna", "labra"};
+  interleave(
+      Doodles, OS, [&](const char *Name) { OS << Name << "doodle"; }, ", ");
+
+  EXPECT_EQ(OS.str(), "goldendoodle, bernadoodle, labradoodle");
+}
+
+TEST(InterleaveTest, InterleaveComma) {
+  std::string Str;
+  raw_string_ostream OS(Str);
+
+  // Check that interleaveComma uses ADL to find begin/end on an array.
+  const StringRef LongDogs[] = {"dachshund", "doxie", "dackel", "teckel"};
+  interleaveComma(LongDogs, OS);
+
+  EXPECT_EQ(OS.str(), "dachshund, doxie, dackel, teckel");
+}
+
+} // anonymous namespace