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

[Björn Schäpers via cfe-commits]

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

None

>From 3da91f4114bf7459812579fb823239aeca5201b9 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   | 2 ++
 clang/unittests/Format/FormatTest.cpp | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index f6341ff0305a9..376afa52cab20 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -3743,6 +3743,8 @@ static FormatToken *getFunctionName(const AnnotatedLine &Line,
         return nullptr;
 
       Tok = Tok->MatchingParen;
+      if (!Tok)
+        break;
 
       continue;
     }
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 5cdac66d1dcbd..068bd22efcf99 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -29053,6 +29053,10 @@ TEST_F(FormatTest, KeywordedFunctionLikeMacros) {
                Style);
 }
 
+TEST_F(FormatTest, DoesNotCrashIncompleteCode) {
+  verifyNoCrash("template <");
+}
+
 } // namespace
 } // namespace test
 } // namespace format