Fix #12403 FP mallocOnClassWarning for RAII class (#5930)

Author: chrchr-github

lib/checkclass.cpp

@@ -1429,8 +1429,12 @@ void CheckClass::checkMemset()
                     const std::set<const Scope *> parsedTypes;
                     checkMemsetType(scope, tok, type, false, parsedTypes);
                 }
-            } else if (tok->variable() && tok->variable()->typeScope() && Token::Match(tok, "%var% = %name% (") &&
-                       (mSettings->library.getAllocFuncInfo(tok->tokAt(2)) || mSettings->library.getReallocFuncInfo(tok->tokAt(2)))) {
+            } else if (tok->variable() && tok->variable()->typeScope() && Token::Match(tok, "%var% = %name% (")) {
+                const Library::AllocFunc* alloc = mSettings->library.getAllocFuncInfo(tok->tokAt(2));
+                if (!alloc)
+                    alloc = mSettings->library.getReallocFuncInfo(tok->tokAt(2));
+                if (!alloc || alloc->bufferSize == Library::AllocFunc::BufferSize::none)
+                    continue;
                 const std::set<const Scope *> parsedTypes;
                 checkMemsetType(scope, tok->tokAt(2), tok->variable()->typeScope(), true, parsedTypes);
 

test/testclass.cpp

@@ -2955,7 +2955,7 @@ class TestClass : public TestFixture {
 
 #define checkNoMemset(...) checkNoMemset_(__FILE__, __LINE__, __VA_ARGS__)
     void checkNoMemset_(const char* file, int line, const char code[]) {
-        const Settings settings = settingsBuilder().severity(Severity::warning).severity(Severity::portability).library("std.cfg").build();
+        const Settings settings = settingsBuilder().severity(Severity::warning).severity(Severity::portability).library("std.cfg").library("posix.cfg").build();
         checkNoMemset_(file, line, code, settings);
     }
 
@@ -3587,6 +3587,17 @@ class TestClass : public TestFixture {
                       "    p = malloc(sizeof(C));\n"
                       "}");
         ASSERT_EQUALS("", errout.str());
+
+        checkNoMemset("class AutoCloseFD {\n"
+                      "    int fd;\n"
+                      "public:\n"
+                      "    AutoCloseFD(int fd);\n"
+                      "    ~AutoCloseFD();\n"
+                      "};\n"
+                      "void f() {\n"
+                      "    AutoCloseFD fd = open(\"abc\", O_RDONLY | O_CLOEXEC);\n"
+                      "}");
+        ASSERT_EQUALS("", errout.str());
     }
 
 #define checkThisSubtraction(code) checkThisSubtraction_(code, __FILE__, __LINE__)