Fix #9931 FP zerodiv (daca@home) (#4379)

* Fix #9931 FP zerodiv (daca@home)

* Format

* Parentheses

* clang-tidy

lib/valueflow.cpp

@@ -1206,7 +1206,7 @@ static Token * valueFlowSetConstantValue(Token *tok, const Settings *settings, b
 
         const Token *tok2 = tok->tokAt(2);
         // skip over tokens to find variable or type
-        while (Token::Match(tok2, "%name% ::|.|[")) {
+        while (tok2 && !tok2->isStandardType() && Token::Match(tok2, "%name% ::|.|[")) {
             if (tok2->next()->str() == "[")
                 tok2 = tok2->linkAt(1)->next();
             else
@@ -1323,7 +1323,24 @@ static Token * valueFlowSetConstantValue(Token *tok, const Settings *settings, b
             }
         } else if (!tok2->type()) {
             const ValueType& vt = ValueType::parseDecl(tok2, settings);
-            const size_t sz = ValueFlow::getSizeOf(vt, settings);
+            size_t sz = ValueFlow::getSizeOf(vt, settings);
+            const Token* brac = tok2->astParent();
+            while (Token::simpleMatch(brac, "[")) {
+                const Token* num = brac->astOperand2();
+                if (num && ((num->isNumber() && MathLib::isInt(num->str())) || num->tokType() == Token::eChar)) {
+                    try {
+                        MathLib::biguint dim = MathLib::toULongNumber(num->str());
+                        sz *= dim;
+                        brac = brac->astParent();
+                        continue;
+                    }
+                    catch (const std::exception& /*e*/) {
+                        // Bad integer literal
+                    }
+                }
+                sz = 0;
+                break;
+            }
             if (sz > 0) {
                 ValueFlow::Value value(sz);
                 if (!tok2->isTemplateArg() && settings->platformType != cppcheck::Platform::Unspecified)

test/testother.cpp

@@ -66,6 +66,7 @@ private:
         TEST_CASE(zeroDiv14); // #1169
         TEST_CASE(zeroDiv15); // #8319
         TEST_CASE(zeroDiv16); // #11158
+        TEST_CASE(zeroDiv17); // #9931
 
         TEST_CASE(zeroDivCond); // division by zero / useless condition
 
@@ -637,6 +638,15 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
+    void zeroDiv17() { // #9931
+        check("int f(int len) {\n"
+              "    int sz = sizeof(void*[255]) / 255;\n"
+              "    int x = len % sz;\n"
+              "    return x;\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
+    }
+
     void zeroDivCond() {
         check("void f(unsigned int x) {\n"
               "  int y = 17 / x;\n"

test/testvalueflow.cpp

@@ -1343,6 +1343,11 @@ private:
         values = tokenValues(code,"( arr )");
         ASSERT_EQUALS(1U, values.size());
         ASSERT_EQUALS(10 * sizeof(std::uint16_t), values.back().intvalue);
+
+        code = "int sz = sizeof(int32_t[10][20]);";
+        values = tokenValues(code, "=");
+        ASSERT_EQUALS(1U, values.size());
+        ASSERT_EQUALS(sizeof(std::int32_t) * 10 * 20, values.back().intvalue);
     }
 
     void valueFlowErrorPath() {