[clang] [clang-format] Don't crash on incomplete template declaration (PR #173433)

[Björn Schäpers via cfe-commits]

https://github.com/HazardyKnusperkeks updated https://github.com/llvm/llvm-project/pull/173433

>From c7bc9e36f67976c44857f26d3f282b630ae496c7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Sch=C3=A4pers?= <bjoern at hazardy.de>
Date: Wed, 24 Dec 2025 01:12:59 +0100
Subject: [PATCH] [clang-format] Don't crash on incomplete template declaration

---
 clang/lib/Format/TokenAnnotator.cpp   | 10 ++++++----
 clang/unittests/Format/FormatTest.cpp |  2 ++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index f6341ff0305a9..1123ae98c02ca 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -3711,7 +3711,7 @@ static FormatToken *getFunctionName(const AnnotatedLine &Line,
     if (Tok->is(TT_AttributeLSquare)) {
       Tok = Tok->MatchingParen;
       if (!Tok)
-        break;
+        return nullptr;
       continue;
     }
 
@@ -3743,6 +3743,8 @@ static FormatToken *getFunctionName(const AnnotatedLine &Line,
         return nullptr;
 
       Tok = Tok->MatchingParen;
+      if (!Tok)
+        return nullptr;
 
       continue;
     }
@@ -3751,7 +3753,7 @@ static FormatToken *getFunctionName(const AnnotatedLine &Line,
     if (Tok->is(tok::coloncolon)) {
       Tok = Tok->Next;
       if (!Tok)
-        break;
+        return nullptr;
     }
 
     // Skip to the unqualified part of the name.
@@ -3765,12 +3767,12 @@ static FormatToken *getFunctionName(const AnnotatedLine &Line,
     if (Tok->is(tok::tilde)) {
       Tok = Tok->Next;
       if (!Tok)
-        break;
+        return nullptr;
     }
 
     // Make sure the name is not already annotated, e.g. as NamespaceMacro.
     if (Tok->isNot(tok::identifier) || Tok->isNot(TT_Unknown))
-      break;
+      return nullptr;
 
     Name = Tok;
   }
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 5cdac66d1dcbd..f5f23388453ec 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -29053,6 +29053,8 @@ TEST_F(FormatTest, KeywordedFunctionLikeMacros) {
                Style);
 }
 
+TEST_F(FormatTest, UnbalancedAngleBrackets) { verifyFormat("template <"); }
+
 } // namespace
 } // namespace test
 } // namespace format