modernize-loop-convert check triggers "Multiple diagnostics in flight at once!" assertion

[hokein]

Reproduce code:

#include <map>
struct LabelInfo {
  int a;
  bool b, c;
  int d;
};

void f() {
  std::map<int, LabelInfo> label_info_map;
   for (auto label_it = label_info_map.begin();
             label_it != label_info_map.end(); ++label_it) {
      const LabelInfo& label_info = label_it->second;
   }
}

Crash stack:

assert.h assertion failed at llvm/tools/clang/include/clang/Basic/Diagnostic.h:1293 in clang::DiagnosticBuilder clang::DiagnosticsEngine::Report(clang::SourceLocation, unsigned int): CurDiagID == std::numeric_limits<unsigned>::max() && "Multiple diagnostics in flight at once!"
*** Check failure stack trace: ***
    @     0x560c2e128722  absl::logging_internal::LogMessage::DieIfFatal()
    @     0x560c2e1276d4  absl::logging_internal::LogMessage::Flush()
    @     0x560c2e129f49  absl::logging_internal::LogMessageFatal::~LogMessageFatal()
    @     0x560c2e1260c6  __assert_fail
    @     0x560c2d958793  (anonymous namespace)::ItaniumRecordLayoutBuilder::CheckFieldPadding()
    @     0x560c2d957a40  (anonymous namespace)::ItaniumRecordLayoutBuilder::LayoutField()
    @     0x560c2d952eab  (anonymous namespace)::ItaniumRecordLayoutBuilder::LayoutFields()
    @     0x560c2d94bbe7  clang::ASTContext::getASTRecordLayout()
    @     0x560c2d94a72f  clang::ASTContext::getASTRecordLayout()
    @     0x560c2d700c6c  clang::ASTContext::getTypeInfoImpl()
    @     0x560c2d70200e  clang::ASTContext::getTypeInfo()
    @     0x560c2d700b9d  clang::ASTContext::getTypeInfoImpl()
    @     0x560c2d70200e  clang::ASTContext::getTypeInfo()
    @     0x560c2c668345  clang::tidy::modernize::LoopConvertCheck::doConversion()
    @     0x560c2c669af6  clang::tidy::modernize::LoopConvertCheck::check()
    @     0x560c2d6a58fc  clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::MatchVisitor::visitMatch()
    @     0x560c2d6d1337  clang::ast_matchers::internal::BoundNodesTreeBuilder::visitMatches()
    @     0x560c2d6a5051  clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::matchWithFilter()
    @     0x560c2d6b6ef9  clang::RecursiveASTVisitor<>::TraverseCompoundStmt()
    @     0x560c2d6b57ee  clang::RecursiveASTVisitor<>::TraverseStmt()
    @     0x560c2d6d10a9  clang::RecursiveASTVisitor<>::TraverseFunctionHelper()
    @     0x560c2d6ac756  clang::RecursiveASTVisitor<>::TraverseFunctionDecl()
    @     0x560c2d6a713c  clang::ast_matchers::internal::(anonymous namespace)::MatchASTVisitor::TraverseDecl()
    @     0x560c2d66b78b  clang::ast_matchers::MatchFinder::matchAST()
    @     0x560c2c3bdffe  clang::clangd::ParsedAST::build()
    @     0x560c2c3c0001  clang::clangd::buildAST()

The check calls ASTContext::getTypeInfo(), the ASTContext::getTypeInfo() has a side effect which may produce a new diagnostic and we are current running the check when processing another diagnostic, which triggers this assertion. (the issue only occurs in clangd, not clang-tidy).

It looks like there is no trivial fix for it, we need more investigations.