[clang-format] Fix a bug in removing braces for the LLVM style

[owenpan]

Summary

When an l_brace is wrapped and the line above it ends with a comment, the annotator adds ColumnLimit to the TotalLength of the l_brace, so the actual column position of the l_brace must be adjusted accordingly.

Fixes https://github.com/llvm/llvm-project/issues/57376.

[MyDeveloperDay]

LGTM

clang/lib/Format/UnwrappedLineParser.cpp

bool UnwrappedLineParser::mightFitOnOneLine(
 
   TokenAnnotator Annotator(Style, Keywords);
   Annotator.annotate(Line);
   Annotator.calculateFormattingInformation(Line);
 
   auto Length = LastToken->TotalLength;
   if (OpeningBrace) {
     assert(OpeningBrace != Tokens.front().Tok);
+    if (auto Prev = OpeningBrace->Previous;
+        Prev && Prev->TotalLength + ColumnLimit == OpeningBrace->TotalLength) {
+      Length -= ColumnLimit;
+    }
     Length -= OpeningBrace->TokenText.size() + 1;
   }
 
   Index = 0;
   for (auto &Token : Tokens) {
     const auto &SavedToken = SavedTokens[Index++];
     Token.Tok->copyFrom(*SavedToken.Tok);
     Token.Children = std::move(SavedToken.Children);

clang/unittests/Format/FormatTest.cpp

verifyFormat("if (a) {\n"
                "}",
                "if (a) {\n"
                "  if (b) {\n"
                "    c = 1; // comment\n"
                "  }\n"
                "}",
                Style);
 
+  verifyFormat("if (a) // comment\n"
+               "  b = 1;",
+               "if (a) // comment\n"
+               "{\n"
+               "  b = 1;\n"
+               "}",
+               Style);
+
   verifyFormat("if (a) {\n"
                "Label:\n"
                "}",
                Style);
 
   verifyFormat("if (a) {\n"
                "Label:\n"
                "  f();\n"