[clang-format] Insert closing braces after an unaffected line

[owenpan]

Summary

The token that records the number of closing braces to be inserted may be on an unaffected line. Extra work is required in order to actually insert the closing braces after inserting the matching opening braces of affected lines.

Fixes https://github.com/llvm/llvm-project/issues/58161.

[MyDeveloperDay]

Does this need a unit test? or are we good?

[owenpan]

In D136437#3874832, @MyDeveloperDay wrote:

Does this need a unit test? or are we good?

I will add the tests from https://github.com/llvm/llvm-project/issues/58161 in another patch after moving InsertBraces tests out of FormatTest.cpp, which doesn't support line range tests.

[owenpan]

The assertions failed on the new examples in #58161.

[owenpan]

Fixed assertion failures on the tests in https://github.com/llvm/llvm-project/issues/58161#issuecomment-1287904972.

clang/lib/Format/Format.cpp

analyze(TokenAnnotator &Annotator,
     insertBraces(AnnotatedLines, Result);
     return {Result, 0};
   }
 
 private:
   void insertBraces(SmallVectorImpl<AnnotatedLine *> &Lines,
                     tooling::Replacements &Result) {
     const auto &SourceMgr = Env.getSourceManager();
+    int OpeningBraceSurplus = 0;
     for (AnnotatedLine *Line : Lines) {
       insertBraces(Line->Children, Result);
-      if (!Line->Affected)
+      if (!Line->Affected && OpeningBraceSurplus == 0)
         continue;
       for (FormatToken *Token = Line->First; Token && !Token->Finalized;
            Token = Token->Next) {
-        if (Token->BraceCount == 0)
+        int BraceCount = Token->BraceCount;
+        if (BraceCount == 0)
           continue;
         std::string Brace;
-        if (Token->BraceCount < 0) {
-          assert(Token->BraceCount == -1);
+        if (BraceCount < 0) {
+          assert(BraceCount == -1);
+          if (!Line->Affected)
+            break;
           Brace = Token->is(tok::comment) ? "\n{" : "{";
+          ++OpeningBraceSurplus;
         } else {
-          Brace = '\n' + std::string(Token->BraceCount, '}');
+          if (OpeningBraceSurplus == 0)
+            break;
+          if (OpeningBraceSurplus < BraceCount)
+            BraceCount = OpeningBraceSurplus;
+          Brace = '\n' + std::string(BraceCount, '}');
+          OpeningBraceSurplus -= BraceCount;
         }
         Token->BraceCount = 0;
         const auto Start = Token->Tok.getEndLoc();
         cantFail(Result.add(tooling::Replacement(SourceMgr, Start, 0, Brace)));
       }
     }
+    assert(OpeningBraceSurplus == 0);
   }
 };
 
 class BracesRemover : public TokenAnalyzer {
 public:
   BracesRemover(const Environment &Env, const FormatStyle &Style)
       : TokenAnalyzer(Env, Style) {
     this->Style.InsertBraces = false;