From 099c1527f6088305fc253e9598685faa85544a8e Mon Sep 17 00:00:00 2001
From: Haojian Wu <hokein.wu@gmail.com>
Date: Fri, 10 May 2024 18:13:47 +0200
Subject: [PATCH] [AST] Print the separator "," for template arguments in
 ConceptReference::print (#91750)

---
 clang/lib/AST/ASTConcept.cpp                  |  6 +-
 clang/unittests/AST/CMakeLists.txt            |  1 +
 clang/unittests/AST/ConceptPrinterTest.cpp    | 57 +++++++++++++++++++
 .../gn/secondary/clang/unittests/AST/BUILD.gn |  1 +
 4 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 clang/unittests/AST/ConceptPrinterTest.cpp

diff --git a/clang/lib/AST/ASTConcept.cpp b/clang/lib/AST/ASTConcept.cpp
index b3ec99448b3e13..0387fc9f6aec2d 100644
--- a/clang/lib/AST/ASTConcept.cpp
+++ b/clang/lib/AST/ASTConcept.cpp
@@ -15,6 +15,7 @@
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/PrettyPrinter.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringExtras.h"
 
 using namespace clang;
 
@@ -106,9 +107,12 @@ void ConceptReference::print(llvm::raw_ostream &OS,
   ConceptName.printName(OS, Policy);
   if (hasExplicitTemplateArgs()) {
     OS << "<";
+    llvm::ListSeparator Sep(", ");
     // FIXME: Find corresponding parameter for argument
-    for (auto &ArgLoc : ArgsAsWritten->arguments())
+    for (auto &ArgLoc : ArgsAsWritten->arguments()) {
+      OS << Sep;
       ArgLoc.getArgument().print(Policy, OS, /*IncludeType*/ false);
+    }
     OS << ">";
   }
 }
diff --git a/clang/unittests/AST/CMakeLists.txt b/clang/unittests/AST/CMakeLists.txt
index 54765e36db008b..29d2b39cff8b15 100644
--- a/clang/unittests/AST/CMakeLists.txt
+++ b/clang/unittests/AST/CMakeLists.txt
@@ -24,6 +24,7 @@ add_clang_unittest(ASTTests
   CommentLexer.cpp
   CommentParser.cpp
   CommentTextTest.cpp
+  ConceptPrinterTest.cpp
   DataCollectionTest.cpp
   DeclPrinterTest.cpp
   DeclTest.cpp
diff --git a/clang/unittests/AST/ConceptPrinterTest.cpp b/clang/unittests/AST/ConceptPrinterTest.cpp
new file mode 100644
index 00000000000000..bd1f6bbfa5658e
--- /dev/null
+++ b/clang/unittests/AST/ConceptPrinterTest.cpp
@@ -0,0 +1,57 @@
+//===- unittests/AST/ConceptPrinterTest.cpp --- Concept printer 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 "ASTPrint.h"
+#include "clang/AST/ASTConcept.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/ExprConcepts.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Tooling/Tooling.h"
+#include "llvm/ADT/SmallString.h"
+#include "gtest/gtest.h"
+
+using namespace clang;
+using namespace ast_matchers;
+using namespace tooling;
+
+namespace {
+
+static void PrintConceptReference(raw_ostream &Out, const ASTContext *Context,
+                                  const ConceptSpecializationExpr *T,
+                                  PrintingPolicyAdjuster PolicyAdjuster) {
+  assert(T && T->getConceptReference() &&
+         "Expected non-null concept reference");
+
+  PrintingPolicy Policy = Context->getPrintingPolicy();
+  if (PolicyAdjuster)
+    PolicyAdjuster(Policy);
+  T->getConceptReference()->print(Out, Policy);
+}
+
+::testing::AssertionResult
+PrintedConceptMatches(StringRef Code, const std::vector<std::string> &Args,
+                      const StatementMatcher &NodeMatch,
+                      StringRef ExpectedPrinted) {
+  return PrintedNodeMatches<ConceptSpecializationExpr>(
+      Code, Args, NodeMatch, ExpectedPrinted, "", PrintConceptReference);
+}
+const internal::VariadicDynCastAllOfMatcher<Stmt, ConceptSpecializationExpr>
+    conceptSpecializationExpr;
+} // unnamed namespace
+
+TEST(ConceptPrinter, ConceptReference) {
+  std::string Code = R"cpp(
+    template <typename, typename> concept D = true;
+    template<typename T, typename U>
+    requires D<T, U>
+    void g(T);
+  )cpp";
+  auto Matcher = conceptSpecializationExpr().bind("id");
+
+  ASSERT_TRUE(PrintedConceptMatches(Code, {"-std=c++20"}, Matcher, "D<T, U>"));
+}
diff --git a/llvm/utils/gn/secondary/clang/unittests/AST/BUILD.gn b/llvm/utils/gn/secondary/clang/unittests/AST/BUILD.gn
index 1fb3d621275ed7..f66e86ad938bdd 100644
--- a/llvm/utils/gn/secondary/clang/unittests/AST/BUILD.gn
+++ b/llvm/utils/gn/secondary/clang/unittests/AST/BUILD.gn
@@ -32,6 +32,7 @@ unittest("ASTTests") {
     "CommentLexer.cpp",
     "CommentParser.cpp",
     "CommentTextTest.cpp",
+    "ConceptPrinterTest.cpp",
     "DataCollectionTest.cpp",
     "DeclPrinterTest.cpp",
     "DeclTest.cpp",