Fix #15183 Syntax error with -!! - #9005

AI review

The fix works for ! and ~ after a unary +/-. It is incomplete, though: the same check in concatenateNegativeNumberAndAnyPositive() still reports a false syntaxError on valid code when another prefix operator follows the sign. Examples are return - --i;, return - ++i; and return +&x;. They are the same kind of bug as #15183 and fail the same way on base and on the PR. I found no regressions: invalid code such as return -!; is still rejected, now as internalAstError. return -~; is now accepted silently, but return ~; and return x + ~; are already accepted on base, so that is not new.

Testing

• I built cppcheck and testrunner in pr/, and cppcheck in base/.
• ./testrunner TestTokenizer: 392 tests, 0 failures.
• I compared base and PR on small C files of the form int x; int f(int i) { <stmt> }, run with cppcheck -q --enable=all.
• Fixed by the PR. Base reported syntaxError on each of these and the PR reports nothing wrong:
  • return -!!i;
  • return -~i;
  • return +!i;
  • return x * -!i;
  • return x == -!i;
  • return x < -~i;
  • return i ? -!i : -~i;
  • int a[] = {-!i, +~i};
  • case -!0:
  • return sizeof -!i;
• Still a false syntax error on valid code, the same on base and PR:

int x; int f(int i) { return - --i; }
int x; int f(int i) { return - ++i; }
int x; int f(int i) { return +&x; }

$ ./cppcheck -q u.c
u.c:1:23: error: syntax error [syntaxError]

• Invalid code:
  • return -!; now gives internalAstError; base gave syntaxError.
  • return -~; is now accepted without any error. Base also accepts return ~; and return x + ~;, so this is not a new kind of gap.

Automated review of a05990f by Claude. The pull request was built and tested locally.