Fix #13197 Crash in isExhaustiveSwitch() (#6875)

Author: chrchr-github

lib/tokenlist.cpp

@@ -913,7 +913,7 @@ static bool isPrefixUnary(const Token* tok, bool cpp)
         }
     }
     if (!tok->previous()
-        || ((Token::Match(tok->previous(), "(|[|{|%op%|;|?|:|,|.|return|::") || (cpp && tok->strAt(-1) == "throw"))
+        || ((Token::Match(tok->previous(), "(|[|{|%op%|;|?|:|,|.|case|return|::") || (cpp && tok->strAt(-1) == "throw"))
             && (tok->previous()->tokType() != Token::eIncDecOp || tok->tokType() == Token::eIncDecOp)))
         return true;
 
@@ -1893,6 +1893,11 @@ void TokenList::validateAst(bool print) const
                                     "' doesn't have two operands.",
                                     InternalError::AST);
         }
+        if (tok->str() == "case" && !tok->astOperand1()) {
+            throw InternalError(tok,
+                                "Syntax Error: AST broken, 'case' doesn't have an operand.",
+                                InternalError::AST);
+        }
 
         // Check member access
         if (Token::Match(tok, "%var% .")) {

test/testtokenize.cpp

@@ -6903,6 +6903,7 @@ class TestTokenizer : public TestFixture {
         ASSERT_EQUALS("12+case", testAst("case 1+2:"));
         ASSERT_EQUALS("xyz:?case", testAst("case (x?y:z):"));
         ASSERT_EQUALS("switchx( 1case y++ 2case", testAst("switch(x){case 1:{++y;break;case 2:break;}}"));
+        ASSERT_EQUALS("switchi( 12<<~case 0return", testAst("switch (i) { case ~(1 << 2) : return 0; }")); // #13197
     }
 
     void astrefqualifier() {