Fix #14866 FP bufferAccessOutOfBounds with vector and gethostname() (cppcheck-opensource#8667)

Co-authored-by: chrchr-github <noreply@github.com>

Author: chrchr-github

lib/checkbufferoverrun.cpp

@@ -574,7 +574,7 @@ ValueFlow::Value CheckBufferOverrunImpl::getBufferSize(const Token *bufTok) cons
             return *value;
     }
 
-    if (!var || var->isPointer())
+    if (!var || var->isPointer() || (astIsContainer(bufTok) && var->getTypeName() != "std::array"))
         return ValueFlow::Value(-1);
 
     const MathLib::bigint dim = std::accumulate(var->dimensions().cbegin(), var->dimensions().cend(), MathLib::bigint(1), [](MathLib::bigint i1, const Dimension &dim) {

test/testbufferoverrun.cpp

@@ -3539,6 +3539,12 @@ class TestBufferOverrun : public TestFixture {
                            "[test.cpp:7:12]: (error) Buffer is accessed out of bounds: &a[0][0] [bufferAccessOutOfBounds]\n",
                            "",
                            errout_str());
+
+        check("void f() {\n" // #14866
+              "    std::vector<char> buf(25);\n"
+              "    std::memset(&buf[0], 0, 25);\n"
+              "}\n");
+        ASSERT_EQUALS("", errout_str());
     }
 
     void buffer_overrun_errorpath() {