[clang] [clang-format] Handle possible crash in `getCells` (PR #77723)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-format

Author: None (XDeme)

<details>
<summary>Changes</summary>

Done as requested in llvm/llvm-project#<!-- -->77045

---
Full diff: https://github.com/llvm/llvm-project/pull/77723.diff


2 Files Affected:

- (modified) clang/lib/Format/WhitespaceManager.cpp (+3-1) 
- (modified) clang/unittests/Format/FormatTest.cpp (+10) 


``````````diff
diff --git a/clang/lib/Format/WhitespaceManager.cpp b/clang/lib/Format/WhitespaceManager.cpp
index f1d176f182ffa4..8415c8d360d640 100644
--- a/clang/lib/Format/WhitespaceManager.cpp
+++ b/clang/lib/Format/WhitespaceManager.cpp
@@ -1451,8 +1451,10 @@ WhitespaceManager::CellDescriptions WhitespaceManager::getCells(unsigned Start,
       } else if (C.Tok->is(tok::comma)) {
         if (!Cells.empty())
           Cells.back().EndIndex = i;
-        if (C.Tok->getNextNonComment()->isNot(tok::r_brace)) // dangling comma
+        if (const auto *Next = C.Tok->getNextNonComment();
+            Next && Next->isNot(tok::r_brace)) { // dangling comma
           ++Cell;
+        }
       }
     } else if (Depth == 1) {
       if (C.Tok == MatchingParen) {
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 8f115fb8cbf0fb..e710765d454d01 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -20931,6 +20931,11 @@ TEST_F(FormatTest, CatchAlignArrayOfStructuresRightAlignment) {
       "};",
       Style);
 
+  verifyNoCrash("Foo f[] = {\n"
+                "    [0] = { 1, },\n"
+                "    [1] { 1, },\n"
+                "};",
+                Style);
   verifyNoCrash("Foo foo[] = {\n"
                 "    [0] = {1, 1},\n"
                 "    [1] { 1, 1, },\n"
@@ -21179,6 +21184,11 @@ TEST_F(FormatTest, CatchAlignArrayOfStructuresLeftAlignment) {
       "};",
       Style);
 
+  verifyNoCrash("Foo f[] = {\n"
+                "    [0] = { 1, },\n"
+                "    [1] { 1, },\n"
+                "};",
+                Style);
   verifyNoCrash("Foo foo[] = {\n"
                 "    [0] = {1, 1},\n"
                 "    [1] { 1, 1, },\n"

``````````

</details>


https://github.com/llvm/llvm-project/pull/77723