release/20.x: [clang-format] Fix a crash on formatting missing r_paren/r_brace (#138230)

owenca · tstellar · commit 2d079b96a5fb · 2025-05-13T14:28:28.000-07:00
Backport 79210fe
diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -1837,8 +1837,8 @@ void UnwrappedLineParser::parseStructuralElement(
       nextToken();
       if (FormatTok->is(tok::l_paren)) {
         parseParens();
-        assert(FormatTok->Previous);
-        if (FormatTok->Previous->endsSequence(tok::r_paren, tok::kw_auto,
+        if (FormatTok->Previous &&
+            FormatTok->Previous->endsSequence(tok::r_paren, tok::kw_auto,
                                               tok::l_paren)) {
           Line->SeenDecltypeAuto = true;
         }
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
@@ -13962,6 +13962,8 @@ TEST_F(FormatTest, IncorrectCodeUnbalancedBraces) {
   verifyNoCrash("struct Foo {\n"
                 "  operator foo(bar\n"
                 "};");
+  verifyNoCrash("decltype( {\n"
+                "  {");
 }
 
 TEST_F(FormatTest, IncorrectUnbalancedBracesInMacrosWithUnicode) {

Original file line number	Diff line number	Diff line change
`@@ -13962,6 +13962,8 @@ TEST_F(FormatTest, IncorrectCodeUnbalancedBraces) {`
`13962`	`13962`	`verifyNoCrash("struct Foo {\n"`
`13963`	`13963`	`" operator foo(bar\n"`
`13964`	`13964`	`"};");`
	`13965`	`+ verifyNoCrash("decltype( {\n"`
	`13966`	`+ " {");`
`13965`	`13967`	`}`
`13966`	`13968`
`13967`	`13969`	`TEST_F(FormatTest, IncorrectUnbalancedBracesInMacrosWithUnicode) {`