[clang] [TableGen] Use ListSeparator (NFC) (PR #144936)

[Kazu Hirata via cfe-commits]

https://github.com/kazutakahirata created https://github.com/llvm/llvm-project/pull/144936

Note that an instance of ListSeparator evaluates to the empty string
for the first time and then ", " for subsequent references.


>From f0907a039a6de8fe305a5eac1b4e41fd1adff7bd Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Mon, 16 Jun 2025 00:35:25 -0700
Subject: [PATCH] [TableGen] Use ListSeparator (NFC)

Note that an instance of ListSeparator evaluates to the empty string
for the first time and then ", " for subsequent references.
---
 clang/utils/TableGen/ClangAttrEmitter.cpp        | 6 ++----
 clang/utils/TableGen/ClangDiagnosticsEmitter.cpp | 9 +++------
 2 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/clang/utils/TableGen/ClangAttrEmitter.cpp b/clang/utils/TableGen/ClangAttrEmitter.cpp
index f892626a447e5..dfeb6b1b1ec19 100644
--- a/clang/utils/TableGen/ClangAttrEmitter.cpp
+++ b/clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -5482,14 +5482,12 @@ void EmitTestPragmaAttributeSupportedAttributes(const RecordKeeper &Records,
     }
     const Record *SubjectObj = I.second->getValueAsDef("Subjects");
     OS << " (";
-    bool PrintComma = false;
+    ListSeparator LS;
     for (const auto &Subject :
          enumerate(SubjectObj->getValueAsListOfDefs("Subjects"))) {
       if (!isSupportedPragmaClangAttributeSubject(*Subject.value()))
         continue;
-      if (PrintComma)
-        OS << ", ";
-      PrintComma = true;
+      OS << LS;
       PragmaClangAttributeSupport::RuleOrAggregateRuleSet &RuleSet =
           Support.SubjectsToRules.find(Subject.value())->getSecond();
       if (RuleSet.isRule()) {
diff --git a/clang/utils/TableGen/ClangDiagnosticsEmitter.cpp b/clang/utils/TableGen/ClangDiagnosticsEmitter.cpp
index bfc60f485cd32..b28cb2c09ac5c 100644
--- a/clang/utils/TableGen/ClangDiagnosticsEmitter.cpp
+++ b/clang/utils/TableGen/ClangDiagnosticsEmitter.cpp
@@ -2225,13 +2225,10 @@ void clang::EmitClangDiagDocs(const RecordKeeper &Records, raw_ostream &OS) {
       else
         OS << "Also controls ";
 
-      bool First = true;
       sort(GroupInfo.SubGroups);
-      for (StringRef Name : GroupInfo.SubGroups) {
-        if (!First) OS << ", ";
-        OS << "`" << (IsRemarkGroup ? "-R" : "-W") << Name << "`_";
-        First = false;
-      }
+      ListSeparator LS;
+      for (StringRef Name : GroupInfo.SubGroups)
+        OS << LS << "`" << (IsRemarkGroup ? "-R" : "-W") << Name << "`_";
       OS << ".\n\n";
     }