Fix 10223: ValueFlow; known value for a volatile variable (#3658)

lib/valueflow.cpp

@@ -4883,6 +4883,12 @@ static void valueFlowForwardAssign(Token* const tok,
     if (vars.size() == 1 && vars.front()->isStatic() && init)
         lowerToPossible(values);
 
+    // is volatile
+    if (std::any_of(vars.begin(), vars.end(), [&](const Variable* var) {
+        return var->isVolatile();
+    }))
+        lowerToPossible(values);
+
     // Skip RHS
     const Token * nextExpression = tok->astParent() ? nextAfterAstRightmostLeaf(tok->astParent()) : tok->next();
 

test/testcondition.cpp

@@ -3838,6 +3838,18 @@ private:
               "  if (b) {}\n"
               "}\n");
         ASSERT_EQUALS("", errout.str());
+
+        // #10223
+        check("static volatile sig_atomic_t is_running;\n"
+              "static void handler(int signum) {\n"
+              "    is_running = 0;\n"
+              "}\n"
+              "void f() {\n"
+              "    signal(SIGINT, &handler);\n"
+              "    is_running = 1;\n"
+              "    while (is_running) {}\n"
+              "}\n");
+        ASSERT_EQUALS("", errout.str());
     }
 
     void alwaysTrueSymbolic()