enabled and mitigated `readability-container-size-empty` clang-tidy warnings (#5340)

.clang-tidy

@@ -56,7 +56,6 @@ Checks: >
         -readability-braces-around-statements,
         -readability-const-return-type,
         -readability-container-data-pointer,
-        -readability-container-size-empty,
         -readability-convert-member-functions-to-static,
         -readability-function-cognitive-complexity,
         -readability-function-size,

clang-tidy.md

@@ -128,7 +128,6 @@ Also reports a false positive about templates which deduce the array length: htt
 
 We run this separately via `clang-include-cleaner` in the `iwyu.yml` workflow as the findings of the include checkers still need to be reviewed manually before applying them. 
 
-`readability-container-size-empty`<br/>
 `bugprone-branch-clone`<br/>
 `readability-const-return-type`<br/>
 `modernize-return-braced-init-list`<br/>

gui/mainwindow.cpp

@@ -697,7 +697,7 @@ void MainWindow::analyzeFiles()
 
     QStringList selected = selectFilesToAnalyze(QFileDialog::ExistingFiles);
 
-    const QString file0 = (selected.size() ? selected[0].toLower() : QString());
+    const QString file0 = (!selected.empty() ? selected[0].toLower() : QString());
     if (file0.endsWith(".sln")
         || file0.endsWith(".vcxproj")
         || file0.endsWith(compile_commands_json)

gui/test/cppchecklibrarydata/testcppchecklibrarydata.cpp

@@ -620,7 +620,7 @@ void TestCppcheckLibraryData::validateAllCfg()
 {
     const QDir dir(QString(SRCDIR) + "/../../../cfg/");
     const QStringList files = dir.entryList(QStringList() << "*.cfg",QDir::Files);
-    QVERIFY(files.size() != 0);
+    QVERIFY(!files.empty());
     bool error = false;
     for (const QString& f : files) {
         loadCfgFile(dir.absolutePath() + "/" + f, fileLibraryData, result);

lib/checkother.cpp

@@ -3529,8 +3529,8 @@ void CheckOther::funcArgOrderDifferent(const std::string & functionName,
                                        const std::vector<const Token *> & definitions)
 {
     std::list<const Token *> tokens = {
-        declarations.size() ? declarations[0] ? declarations[0] : declaration : nullptr,
-        definitions.size() ? definitions[0] ? definitions[0] : definition : nullptr
+        !declarations.empty() ? declarations[0] ? declarations[0] : declaration : nullptr,
+        !definitions.empty() ? definitions[0] ? definitions[0] : definition : nullptr
     };
     std::string msg = "$symbol:" + functionName + "\nFunction '$symbol' argument order different: declaration '";
     for (int i = 0; i < declarations.size(); ++i) {

lib/templatesimplifier.cpp

@@ -3356,7 +3356,7 @@ void TemplateSimplifier::replaceTemplateUsage(
         std::set<TemplateSimplifier::TokenAndName*>* pointers = nameTok->templateSimplifierPointers();
 
         // check if instantiation matches token instantiation from pointer
-        if (pointers && pointers->size()) {
+        if (pointers && !pointers->empty()) {
             // check full name
             if (instantiation.fullName() != (*pointers->begin())->fullName()) {
                 // FIXME:  fallback to just matching name

test/testsymboldatabase.cpp

@@ -1921,6 +1921,7 @@ private:
         ASSERT_EQUALS(10, db->variableList().size() - 1);
         ASSERT_EQUALS(true, db->getVariableFromVarId(1) && db->getVariableFromVarId(1)->dimensions().size() == 1);
         ASSERT_EQUALS(true, db->getVariableFromVarId(2) != nullptr);
+        // NOLINTNEXTLINE(readability-container-size-empty)
         ASSERT_EQUALS(true, db->getVariableFromVarId(3) && db->getVariableFromVarId(3)->dimensions().size() == 0);
         ASSERT_EQUALS(true, db->getVariableFromVarId(4) != nullptr);
         ASSERT_EQUALS(true, db->getVariableFromVarId(5) != nullptr);

test/testvalueflow.cpp

@@ -6616,7 +6616,7 @@ private:
                "  if (a.empty() && b.empty()) {}\n"
                "  else if (a.empty() == false && b.empty() == false) {}\n"
                "}\n";
-        ASSERT("" != isImpossibleContainerSizeValue(tokenValues(code, "a . empty ( ) == false"), 0));
+        ASSERT(!isImpossibleContainerSizeValue(tokenValues(code, "a . empty ( ) == false"), 0).empty());
 
         code = "bool g(std::vector<int>& v) {\n"
                "    v.push_back(1);\n"