FALSE POSITIVE: c++20 bitfields with size and brace intalizer

[tsteven]

cppcheck reports a false positive syntaxError on c++20 bitfields that contain both a size and a brace initializer, which were allowed in c++20. A test case below includes sizes from more complex integral constant expressions, but handling the simple case "int m5:5{55};" would allow the most common usage to proceed in cppcheck.
I reproduced this with 2.19.0 on ubuntu 26.04, but it also fails with main@eb4b6526b3502ee779a74019f814d45d890427ba

• cppcheck --enable=all --std=c++20 test.cc
  Checking test.cc ...
  test.cc:10:12: error: syntax error [syntaxError]
  int m5:5{55};
  ^
  nofile:0:0: information: Active checkers: There was critical errors (use --checkers-report=<filename> to see details) [checkersReport]

  cat test.cc
  int main(int argc, char* argv[])
  {
  constexpr int a = 1;
  constexpr int b = 2;
  struct s {
  int m1;
  int m2:2;
  int m3:3+3;
  int m4:4=44;
  int m5:5{55};
  int maba:a+b{99};
  int m6:6+6{66};
  };
  }

  </filename>

[tsteven]

The syntaxError comes from Tokenizer::findGarbageCode. (line numbers from eb4b6526b3502ee779a74019f814d45d890427ba)

Breakpoint 1.1, Tokenizer::syntaxError (this=0x7fffffffc550, tok=0x555556240920, code="") at /home/tsteven4/work/cppcheck/lib/tokenize.cpp:8441
8441    {
(gdb) bt
#0  Tokenizer::syntaxError (this=0x7fffffffc550, tok=0x555556240920, code="") at /home/tsteven4/work/cppcheck/lib/tokenize.cpp:8441
#1  0x00005555556f183f in Tokenizer::findGarbageCode (this=0x7fffffffc550) at /home/tsteven4/work/cppcheck/lib/tokenize.cpp:9113
#2  0x00005555556dada3 in operator() (__closure=0x7fffffffb860) at /home/tsteven4/work/cppcheck/lib/tokenize.cpp:5846
#3  0x0000555555709866 in Timer::run<Tokenizer::simplifyTokenList1(char const*)::<lambda()> >(std::string, TimerResultsIntf *, const struct {...} &) (str="", timerResults=0x0, f=...)
    at /home/tsteven4/work/cppcheck/lib/timer.h:77
#4  0x00005555556db45b in Tokenizer::simplifyTokenList1 (this=0x7fffffffc550, FileName=0x555556250d60 "/home/tsteven4/work/cppchk/test.cc") at /home/tsteven4/work/cppcheck/lib/tokenize.cpp:5845
#5  0x00005555556cabec in Tokenizer::simplifyTokens1 (this=0x7fffffffc550, configuration="", fileIndex=0) at /home/tsteven4/work/cppcheck/lib/tokenize.cpp:3569
#6  0x0000555555a74ae4 in CppCheck::checkInternal (this=0x7fffffffcea0, file=..., cfgname="", createTokenList=...) at /home/tsteven4/work/cppcheck/lib/cppcheck.cpp:1252
#7  0x0000555555a718bd in CppCheck::checkFile (this=0x7fffffffcea0, file=..., cfgname="") at /home/tsteven4/work/cppcheck/lib/cppcheck.cpp:914
#8  0x0000555555a70266 in CppCheck::check (this=0x7fffffffcea0, file=...) at /home/tsteven4/work/cppcheck/lib/cppcheck.cpp:814
#9  0x0000555555d048ba in SingleExecutor::check (this=0x7fffffffcf30) at /home/tsteven4/work/cppcheck/cli/singleexecutor.cpp:52
#10 0x0000555555ceedfd in CppCheckExecutor::check_internal (this=0x7fffffffdb70, settings=..., supprs=...) at /home/tsteven4/work/cppcheck/cli/cppcheckexecutor.cpp:453
#11 0x0000555555ced2d9 in CppCheckExecutor::check_wrapper (this=0x7fffffffdb70, settings=..., supprs=...) at /home/tsteven4/work/cppcheck/cli/cppcheckexecutor.cpp:295
#12 0x0000555555ced13f in CppCheckExecutor::check (this=0x7fffffffdb70, argc=6, argv=0x7fffffffdd28) at /home/tsteven4/work/cppcheck/cli/cppcheckexecutor.cpp:280
#13 0x0000555555cebc92 in main (argc=6, argv=0x7fffffffdd28) at /home/tsteven4/work/cppcheck/cli/main.cpp:71
(gdb) quit()
❌️ A syntax error in expression, near `)'.

[CHR]

Thanks for reporting, ticket is here: https://trac.cppcheck.net/ticket/15070