Fix #11315 FP zerodivcond from enum definition / #11310 FP unassignedVariable with static variable (#4476)

* Fix #11315 FP zerodivcond from enum definition

* Simplify Boolean expression

* Fix #11310 FP unassignedVariable with static variable

lib/checknullpointer.cpp

@@ -147,9 +147,7 @@ bool CheckNullPointer::isPointerDeRef(const Token *tok, bool &unknown) const
 }
 
 static bool isUnevaluated(const Token* tok) {
-    if (tok && Token::Match(tok->previous(), "sizeof|decltype ("))
-        return true;
-    return false;
+    return tok && Token::Match(tok->previous(), "sizeof|decltype (");
 }
 
 bool CheckNullPointer::isPointerDeRef(const Token *tok, bool &unknown, const Settings *settings)

lib/checkother.cpp

@@ -1990,6 +1990,8 @@ void CheckOther::checkZeroDivision()
             continue;
         if (!tok->valueType() || !tok->valueType()->isIntegral())
             continue;
+        if (tok->scope() && tok->scope()->type == Scope::eEnum) // don't warn for compile-time error
+            continue;
 
         // Value flow..
         const ValueFlow::Value *value = tok->astOperand2()->getValue(0LL);

lib/checkunusedvar.cpp

@@ -1337,9 +1337,11 @@ void CheckUnusedVar::checkFunctionVariableUsage()
                 }
             }
             // variable has not been written but has been modified
-            else if (usage._modified && !usage._write && !usage._allocateMemory && var && !var->isStlType())
+            else if (usage._modified && !usage._write && !usage._allocateMemory && var && !var->isStlType()) {
+                if (var->isStatic()) // static variables are initialized by default
+                    continue;
                 unassignedVariableError(usage._var->nameToken(), varname);
-
+            }
             // variable has been read but not written
             else if (!usage._write && !usage._allocateMemory && var && !var->isStlType() && !isEmptyType(var->type()))
                 unassignedVariableError(usage._var->nameToken(), varname);

test/testother.cpp

@@ -794,6 +794,14 @@ private:
               "    return remainder;\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        // #11315
+        checkP("#define STATIC_ASSERT(c) \\\n"
+               "do { enum { sa = 1/(int)(!!(c)) }; } while (0)\n"
+               "void f() {\n"
+               "    STATIC_ASSERT(sizeof(int) == sizeof(FOO));\n"
+               "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void nanInArithmeticExpression() {

test/testunusedvar.cpp

@@ -5473,6 +5473,13 @@ private:
                               "    array[value] = 1;\n"
                               "}");
         ASSERT_EQUALS("", errout.str());
+
+        functionVariableUsage("int fun() {\n" // #11310
+                              "    static int k;\n"
+                              "    k++;\n"
+                              "    return k;\n"
+                              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void localvarextern() {