update supported cmake versions and add some tests with newer compilers (#972)

Update and test with some newer compilers and cmake versions

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

.ci/azure-cmake-new.yml

@@ -0,0 +1,17 @@
+steps:
+  # Note that silkeh/clang does not include ca-certificates, so check the shasum for verification
+  - bash: |
+      wget --no-check-certificate "https://cmake.org/files/v3.28/cmake-3.28.0-linux-x86_64.tar.gz"
+      echo "898f0b5ca6e2ea5286998e97bd33f030d7d09f18ca4b88be661fdfbad5dadd88  cmake-3.28.0-linux-x86_64.tar.gz" | shasum -sca 256
+    displayName: Download CMake
+
+  - task: ExtractFiles@1
+    inputs:
+      archiveFilePatterns: "cmake*.tar.gz"
+      destinationFolder: "cmake_program"
+      displayName: Extract CMake
+
+  - bash:
+      echo
+      "##vso[task.prependpath]$(Build.SourcesDirectory)/cmake_program/cmake-3.28.0-linux-x86_64/bin"
+    displayName: Add CMake to PATH

.clang-tidy

@@ -6,6 +6,7 @@
 # modernize-avoid-c-arrays trips up in TEMPLATE_TEST_CASE catch macro
 # modernize-return-braced-init-list triggers on lambdas ?
 # modernize-make-unique requires C++14
+# modernize-type_traits requires C++17
 # readability-avoid-const-params-in-decls Affected by the pre-compile split
 
 Checks: |
@@ -37,6 +38,8 @@ Checks: |
   -modernize-concat-nested-namespaces,
   -modernize-return-braced-init-list,
   -modernize-make-unique,
+  -modernize-type-traits,
+  -modernize-macro-to-enum,
   *performance*,
   -performance-unnecessary-value-param,
   -performance-inefficient-string-concatenation,

.github/workflows/tests.yml

@@ -60,7 +60,7 @@ jobs:
   clang-tidy:
     name: Clang-Tidy
     runs-on: ubuntu-latest
-    container: silkeh/clang:14
+    container: silkeh/clang:17
     steps:
       - uses: actions/checkout@v4
 
@@ -91,7 +91,7 @@ jobs:
   cuda12-build:
     name: CUDA 12 build only
     runs-on: ubuntu-latest
-    container: nvidia/cuda:12.1.0-devel-ubuntu22.04
+    container: nvidia/cuda:12.3.1-devel-ubuntu22.04
     steps:
       - name: Add build tools
         run: apt-get update && apt-get install -y wget git cmake
@@ -336,9 +336,15 @@ jobs:
           args: -DCLI11_SANITIZERS=ON -DCLI11_BUILD_EXAMPLES_JSON=ON
         if: success() || failure()
 
-      - name: Check CMake 3.27 (full)
+      - name: Check CMake 3.27
         uses: ./.github/actions/quick_cmake
         with:
           cmake-version: "3.27"
+        if: success() || failure()
+        
+      - name: Check CMake 3.28 (full)
+        uses: ./.github/actions/quick_cmake
+        with:
+          cmake-version: "3.28"
           args: -DCLI11_SANITIZERS=ON -DCLI11_BUILD_EXAMPLES_JSON=ON
         if: success() || failure()

CMakeLists.txt

@@ -2,14 +2,14 @@ cmake_minimum_required(VERSION 3.5)
 # Note: this is a header only library. If you have an older CMake than 3.5,
 # just add the CLI11/include directory and that's all you need to do.
 
-# Make sure users don't get warnings on a tested (3.5 to 3.26) version
+# Make sure users don't get warnings on a tested (3.5 to 3.28) version
 # of CMake. For most of the policies, the new version is better (hence the change).
-# We don't use the 3.5...3.26 syntax because of a bug in an older MSVC's
+# We don't use the 3.5...3.28 syntax because of a bug in an older MSVC's
 # built-in and modified CMake 3.11
-if(${CMAKE_VERSION} VERSION_LESS 3.26)
+if(${CMAKE_VERSION} VERSION_LESS 3.28)
   cmake_policy(VERSION ${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION})
 else()
-  cmake_policy(VERSION 3.26)
+  cmake_policy(VERSION 3.28)
 endif()
 
 set(VERSION_REGEX "#define CLI11_VERSION[ \t]+\"(.+)\"")

azure-pipelines.yml

@@ -150,3 +150,28 @@ jobs:
       - template: .ci/azure-cmake.yml
       - template: .ci/azure-build.yml
       - template: .ci/azure-test.yml
+
+  - job: Docker_new
+    variables:
+      cli11.single: OFF
+    pool:
+      vmImage: "ubuntu-latest"
+    strategy:
+      matrix:
+        gcc13:
+          containerImage: gcc:13
+          cli11.std: 17
+          cli11.options: -DCMAKE_CXX_FLAGS="-Wstrict-overflow=5"
+        gcc12:
+          containerImage: gcc:12
+          cli11.std: 20
+          cli11.options: -DCMAKE_CXX_FLAGS="-Wredundant-decls -Wconversion"
+        clang17_20:
+          containerImage: silkeh/clang:17
+          cli11.std: 23
+          cli11.options: -DCMAKE_CXX_FLAGS=-std=c++23
+    container: $[ variables['containerImage'] ]
+    steps:
+      - template: .ci/azure-cmake-new.yml
+      - template: .ci/azure-build.yml
+      - template: .ci/azure-test.yml

book/chapters/options.md

@@ -283,7 +283,7 @@ CLI::Option* opt = app.add_flag("--opt");
 CLI11_PARSE(app, argv, argc);
 
 if(* opt)
-    std::cout << "Flag received " << opt->count() << " times." << std::endl;
+    std::cout << "Flag received " << opt->count() << " times." << '\n';
 ```
 
 ## Inheritance of defaults

examples/arg_capture.cpp

@@ -25,10 +25,10 @@ int main(int argc, const char *argv[]) {
     subcom->alias("--sub");
     CLI11_PARSE(app, argc, argv);
 
-    std::cout << "value=" << value << std::endl;
+    std::cout << "value=" << value << '\n';
     std::cout << "after Args:";
     for(const auto &aarg : subcom->remaining()) {
         std::cout << aarg << " ";
     }
-    std::cout << std::endl;
+    std::cout << '\n';
 }

examples/config_app.cpp

@@ -40,11 +40,11 @@ int main(int argc, char **argv) {
     }
 
     std::cout << "Working on file: " << file << ", direct count: " << app.count("--file")
-              << ", opt count: " << opt->count() << std::endl;
+              << ", opt count: " << opt->count() << '\n';
     std::cout << "Working on count: " << count << ", direct count: " << app.count("--count")
-              << ", opt count: " << copt->count() << std::endl;
+              << ", opt count: " << copt->count() << '\n';
     std::cout << "Received flag: " << v << " (" << flag->count() << ") times\n";
-    std::cout << "Some value: " << value << std::endl;
+    std::cout << "Some value: " << value << '\n';
 
     return 0;
 }

examples/custom_parse.cpp

@@ -23,7 +23,7 @@ using DoubleValues = Values<double>;
 
 // the lexical cast operator should be in the same namespace as the type for ADL to work properly
 bool lexical_cast(const std::string &input, Values<double> & /*v*/) {
-    std::cout << "called correct lexical_cast function ! val: " << input << std::endl;
+    std::cout << "called correct lexical_cast function ! val: " << input << '\n';
     return true;
 }
 

examples/digit_args.cpp

@@ -16,6 +16,6 @@ int main(int argc, char **argv) {
 
     CLI11_PARSE(app, argc, argv);
 
-    std::cout << "value = " << val << std::endl;
+    std::cout << "value = " << val << '\n';
     return 0;
 }

examples/enum.cpp

@@ -27,7 +27,7 @@ int main(int argc, char **argv) {
 
     // CLI11's built in enum streaming can be used outside CLI11 like this:
     using CLI::enums::operator<<;
-    std::cout << "Enum received: " << level << std::endl;
+    std::cout << "Enum received: " << level << '\n';
 
     return 0;
 }

examples/enum_ostream.cpp

@@ -44,7 +44,7 @@ int main(int argc, char **argv) {
 
     // CLI11's built in enum streaming can be used outside CLI11 like this:
     using CLI::enums::operator<<;
-    std::cout << "Enum received: " << level << std::endl;
+    std::cout << "Enum received: " << level << '\n';
 
     return 0;
 }

examples/formatter.cpp

@@ -31,7 +31,7 @@ int main(int argc, char **argv) {
 
     CLI11_PARSE(app, argc, argv);
 
-    std::cout << "This app was meant to show off the formatter, run with -h" << std::endl;
+    std::cout << "This app was meant to show off the formatter, run with -h" << '\n';
 
     return 0;
 }

examples/groups.cpp

@@ -30,10 +30,10 @@ int main(int argc, char **argv) {
     }
 
     std::cout << "Working on file: " << file << ", direct count: " << app.count("--file")
-              << ", opt count: " << opt->count() << std::endl;
+              << ", opt count: " << opt->count() << '\n';
     std::cout << "Working on count: " << count << ", direct count: " << app.count("--count")
-              << ", opt count: " << copt->count() << std::endl;
+              << ", opt count: " << copt->count() << '\n';
-    std::cout << "Some value: " << value << std::endl;
+    std::cout << "Some value: " << value << '\n';
 
     return 0;
 }

examples/inter_argument_order.cpp

@@ -46,6 +46,6 @@ int main(int argc, char **argv) {
 
     // Prove the vector is correct
     for(auto &pair : keyval) {
-        std::cout << pair.first << " : " << pair.second << std::endl;
+        std::cout << pair.first << " : " << pair.second << '\n';
     }
 }

examples/modhelp.cpp

@@ -26,10 +26,10 @@ Note that this will not shortcut `->required` and other similar options.)raw"};
         if(*help)
             throw CLI::CallForHelp();
     } catch(const CLI::Error &e) {
-        std::cout << "Option -a string in help: " << some_option << std::endl;
+        std::cout << "Option -a string in help: " << some_option << '\n';
         return test.exit(e);
     }
 
-    std::cout << "Option -a string: " << some_option << std::endl;
+    std::cout << "Option -a string: " << some_option << '\n';
     return 0;
 }

examples/option_groups.cpp

@@ -33,13 +33,13 @@ int main(int argc, char **argv) {
     CLI11_PARSE(app, argc, argv);
 
     std::string format_type = (csv) ? std::string("CSV") : ((human) ? "human readable" : "binary");
-    std::cout << "Selected " << format_type << " format" << std::endl;
+    std::cout << "Selected " << format_type << " format\n";
     if(!fileLoc.empty()) {
-        std::cout << " sent to file " << fileLoc << std::endl;
+        std::cout << " sent to file " << fileLoc << '\n';
     } else if(!networkAddress.empty()) {
-        std::cout << " sent over network to " << networkAddress << std::endl;
+        std::cout << " sent over network to " << networkAddress << '\n';
     } else {
-        std::cout << " sent to std::cout" << std::endl;
+        std::cout << " sent to std::cout\n";
     }
 
     return 0;

examples/prefix_command.cpp

@@ -25,11 +25,11 @@ int main(int argc, char **argv) {
     for(int v : vals)
         std::cout << ": " << v << " ";
 
-    std::cout << std::endl << "Remaining commands: ";
+    std::cout << '\n' << "Remaining commands: ";
 
     for(const auto &com : more_comms)
         std::cout << com << " ";
-    std::cout << std::endl;
+    std::cout << '\n';
 
     return 0;
 }

examples/shapes.cpp

@@ -18,7 +18,7 @@ int main(int argc, char **argv) {
     int circle_counter{0};
     circle->callback([&radius, &circle_counter] {
         ++circle_counter;
-        std::cout << "circle" << circle_counter << " with radius " << radius << std::endl;
+        std::cout << "circle" << circle_counter << " with radius " << radius << '\n';
     });
 
     circle->add_option("radius", radius, "the radius of the circle")->required();
@@ -32,7 +32,7 @@ int main(int argc, char **argv) {
         if(edge2 == 0) {
             edge2 = edge1;
         }
-        std::cout << "rectangle" << rect_counter << " with edges [" << edge1 << ',' << edge2 << "]" << std::endl;
+        std::cout << "rectangle" << rect_counter << " with edges [" << edge1 << ',' << edge2 << "]\n";
         edge2 = 0;
     });
 
@@ -45,7 +45,7 @@ int main(int argc, char **argv) {
     tri->callback([&sides, &tri_counter] {
         ++tri_counter;
 
-        std::cout << "triangle" << tri_counter << " with sides [" << CLI::detail::join(sides) << "]" << std::endl;
+        std::cout << "triangle" << tri_counter << " with sides [" << CLI::detail::join(sides) << "]\n";
     });
 
     tri->add_option("sides", sides, "the side lengths of the triangle");

examples/simple.cpp

@@ -28,11 +28,11 @@ int main(int argc, char **argv) {
     CLI11_PARSE(app, argc, argv);
 
     std::cout << "Working on file: " << file << ", direct count: " << app.count("--file")
-              << ", opt count: " << opt->count() << std::endl;
+              << ", opt count: " << opt->count() << '\n';
     std::cout << "Working on count: " << count << ", direct count: " << app.count("--count")
-              << ", opt count: " << copt->count() << std::endl;
+              << ", opt count: " << copt->count() << '\n';
     std::cout << "Received flag: " << v << " (" << flag->count() << ") times\n";
-    std::cout << "Some value: " << value << std::endl;
+    std::cout << "Some value: " << value << '\n';
 
     return 0;
 }

examples/subcom_help.cpp

@@ -15,7 +15,7 @@ int main(int argc, char *argv[]) {
     cli_sub.add_option("sub_arg", sub_arg, "Argument for subcommand")->required();
     CLI11_PARSE(cli_global, argc, argv);
     if(cli_sub) {
-        std::cout << "Got: " << sub_arg << std::endl;
+        std::cout << "Got: " << sub_arg << '\n';
     }
     return 0;
 }

examples/subcom_in_files/subcommand_a.cpp

@@ -30,8 +30,8 @@ void setup_subcommand_a(CLI::App &app) {
 /// but having a separate function is cleaner.
 void run_subcommand_a(SubcommandAOptions const &opt) {
     // Do stuff...
-    std::cout << "Working on file: " << opt.file << std::endl;
+    std::cout << "Working on file: " << opt.file << '\n';
     if(opt.with_foo) {
-        std::cout << "Using foo!" << std::endl;
+        std::cout << "Using foo!" << '\n';
     }
 }

examples/subcom_partitioned.cpp

@@ -37,10 +37,10 @@ int main(int argc, char **argv) {
     }
 
     std::cout << "Working on file: " << file << ", direct count: " << impOpt->count("--file")
-              << ", opt count: " << opt->count() << std::endl;
+              << ", opt count: " << opt->count() << '\n';
     std::cout << "Working on count: " << count << ", direct count: " << impOpt->count("--count")
-              << ", opt count: " << copt->count() << std::endl;
+              << ", opt count: " << copt->count() << '\n';
-    std::cout << "Some value: " << value << std::endl;
+    std::cout << "Some value: " << value << '\n';
 
     return 0;
 }

examples/subcommands.cpp

@@ -24,12 +24,11 @@ int main(int argc, char **argv) {
 
     CLI11_PARSE(app, argc, argv);
 
-    std::cout << "Working on --file from start: " << file << std::endl;
+    std::cout << "Working on --file from start: " << file << '\n';
-    std::cout << "Working on --count from stop: " << s->count() << ", direct count: " << stop->count("--count")
+    std::cout << "Working on --count from stop: " << s->count() << ", direct count: " << stop->count("--count") << '\n';
-              << std::endl;
+    std::cout << "Count of --random flag: " << app.count("--random") << '\n';
-    std::cout << "Count of --random flag: " << app.count("--random") << std::endl;
     for(auto *subcom : app.get_subcommands())
-        std::cout << "Subcommand: " << subcom->get_name() << std::endl;
+        std::cout << "Subcommand: " << subcom->get_name() << '\n';
 
     return 0;
 }

examples/testEXE.cpp

@@ -19,10 +19,10 @@ int main(int argc, const char *argv[]) {
     auto *subcom = app.add_subcommand("sub", "")->prefix_command();
     CLI11_PARSE(app, argc, argv);
 
-    std::cout << "value =" << value << std::endl;
+    std::cout << "value =" << value << '\n';
     std::cout << "after Args:";
     for(const auto &aarg : subcom->remaining()) {
         std::cout << aarg << " ";
     }
-    std::cout << std::endl;
+    std::cout << '\n';
 }

examples/validators.cpp

@@ -19,7 +19,7 @@ int main(int argc, char **argv) {
     app.add_option("-v,--value", count, "Value in range")->check(CLI::Range(3, 6));
     CLI11_PARSE(app, argc, argv);
 
-    std::cout << "Try printing help or failing the validator" << std::endl;
+    std::cout << "Try printing help or failing the validator" << '\n';
 
     return 0;
 }

include/CLI/Timer.hpp

@@ -126,7 +126,7 @@ class AutoTimer : public Timer {
     // GCC 4.7 does not support using inheriting constructors.
 
     /// This destructor prints the string
-    ~AutoTimer() { std::cout << to_string() << std::endl; }
+    ~AutoTimer() { std::cout << to_string() << '\n'; }
 };
 
 }  // namespace CLI

include/CLI/TypeTools.hpp

@@ -1384,9 +1384,7 @@ bool lexical_conversion(const std::vector<std ::string> &strings, AssignTo &outp
     FirstType v1;
     SecondType v2;
     bool retval = lexical_assign<FirstType, FirstType>(strings[0], v1);
-    if(strings.size() > 1) {
+    retval = retval && lexical_assign<SecondType, SecondType>((strings.size() > 1) ? strings[1] : std::string{}, v2);
-        retval = retval && lexical_assign<SecondType, SecondType>(strings[1], v2);
-    }
     if(retval) {
         output = AssignTo{v1, v2};
     }

include/CLI/impl/App_inl.hpp

@@ -658,7 +658,7 @@ CLI11_INLINE int App::exit(const Error &e, std::ostream &out, std::ostream &err)
     }
 
     if(e.get_name() == "CallForVersion") {
-        out << e.what() << std::endl;
+        out << e.what() << '\n';
         return e.get_exit_code();
     }
 

include/CLI/impl/Config_inl.hpp

@@ -134,7 +134,11 @@ generate_parents(const std::string &section, std::string &name, char parentSepar
         parents.insert(parents.end(), plist.begin(), plist.end());
     }
     // clean up quotes on the parents
-    detail::remove_quotes(parents);
+    try {
+        detail::remove_quotes(parents);
+    } catch(const std::invalid_argument &iarg) {
+        throw CLI::ParseError(iarg.what(), CLI::ExitCodes::InvalidError);
+    }
     return parents;
 }
 
@@ -341,8 +345,8 @@ inline std::vector<ConfigItem> ConfigBase::from_config(std::istream &input) cons
                         if(keyChar == '\"') {
                             try {
                                 item = detail::remove_escaped_characters(item);
-                            } catch(const std::invalid_argument &ia) {
+                            } catch(const std::invalid_argument &iarg) {
-                                throw CLI::ParseError(ia.what(), CLI::ExitCodes::InvalidError);
+                                throw CLI::ParseError(iarg.what(), CLI::ExitCodes::InvalidError);
                             }
                         }
                     } else {
@@ -366,7 +370,11 @@ inline std::vector<ConfigItem> ConfigBase::from_config(std::istream &input) cons
                     detail::trim(multiline);
                     item += multiline;
                 }
-                items_buffer = detail::split_up(item.substr(1, item.length() - 2), aSep);
+                if(item.back() == aEnd) {
+                    items_buffer = detail::split_up(item.substr(1, item.length() - 2), aSep);
+                } else {
+                    items_buffer = detail::split_up(item.substr(1, std::string::npos), aSep);
+                }
             } else if((isDefaultArray || isINIArray) && item.find_first_of(aSep) != std::string::npos) {
                 items_buffer = detail::split_up(item, aSep);
             } else if((isDefaultArray || isINIArray) && item.find_first_of(' ') != std::string::npos) {

include/CLI/impl/Formatter_inl.hpp

@@ -132,7 +132,7 @@ CLI11_INLINE std::string Formatter::make_usage(const App *app, std::string name)
             << (app->get_require_subcommand_min() == 0 ? "]" : "");
     }
 
-    out << std::endl;
+    out << '\n';
 
     return out.str();
 }

include/CLI/impl/Option_inl.hpp

@@ -623,11 +623,11 @@ CLI11_INLINE void Option::_reduce_results(results_t &out, const results_t &origi
     // {} is the indicator for an empty container
     if(out.empty()) {
         if(original.size() == 1 && original[0] == "{}" && get_items_expected_min() > 0) {
-            out.push_back("{}");
+            out.emplace_back("{}");
-            out.push_back("%%");
+            out.emplace_back("%%");
         }
     } else if(out.size() == 1 && out[0] == "{}" && get_items_expected_min() > 0) {
-        out.push_back("%%");
+        out.emplace_back("%%");
     }
 }
 

tests/ConfigFileTest.cpp

@@ -614,9 +614,9 @@ TEST_CASE_METHOD(TApp, "IniNotRequired", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     int one = 0, two = 0, three = 0;
@@ -651,8 +651,8 @@ TEST_CASE_METHOD(TApp, "IniSuccessOnUnknownOption", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
     }
 
     int two{0};
@@ -671,8 +671,8 @@ TEST_CASE_METHOD(TApp, "IniGetRemainingOption", "[config]") {
     std::string ExtraOptionValue = "3";
     {
         std::ofstream out{tmpini};
-        out << ExtraOption << "=" << ExtraOptionValue << std::endl;
+        out << ExtraOption << "=" << ExtraOptionValue << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
     }
 
     int two{0};
@@ -694,7 +694,7 @@ TEST_CASE_METHOD(TApp, "IniRemainingSub", "[config]") {
         out << "[map]\n";
         out << "a = 1\n";
         out << "b=[1,2,3]\n";
-        out << "c = 3" << std::endl;
+        out << "c = 3" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -727,7 +727,7 @@ TEST_CASE_METHOD(TApp, "IniGetNoRemaining", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
     }
 
     int two{0};
@@ -773,9 +773,9 @@ TEST_CASE_METHOD(TApp, "IniRequiredbadConfigurator", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     app.set_config("--config", tmpini)->required();
@@ -791,9 +791,9 @@ TEST_CASE_METHOD(TApp, "IniNotRequiredbadConfigurator", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     app.set_config("--config", tmpini);
@@ -814,16 +814,16 @@ TEST_CASE_METHOD(TApp, "IniNotRequiredNotDefault", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     {
         std::ofstream out{tmpini2};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=98" << std::endl;
+        out << "two=98" << '\n';
-        out << "three=4" << std::endl;
+        out << "three=4" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -852,9 +852,9 @@ TEST_CASE_METHOD(TApp, "IniEnvironmentalFileName", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -883,16 +883,16 @@ TEST_CASE_METHOD(TApp, "MultiConfig", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     {
         std::ofstream out{tmpini2};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "one=55" << std::endl;
+        out << "one=55" << '\n';
-        out << "three=4" << std::endl;
+        out << "three=4" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -924,16 +924,16 @@ TEST_CASE_METHOD(TApp, "MultiConfig_takelast", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     {
         std::ofstream out{tmpini2};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "one=55" << std::endl;
+        out << "one=55" << '\n';
-        out << "three=4" << std::endl;
+        out << "three=4" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -966,16 +966,16 @@ TEST_CASE_METHOD(TApp, "MultiConfig_takeAll", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     {
         std::ofstream out{tmpini2};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "one=55" << std::endl;
+        out << "one=55" << '\n';
-        out << "three=4" << std::endl;
+        out << "three=4" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1008,16 +1008,16 @@ TEST_CASE_METHOD(TApp, "MultiConfig_single", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     {
         std::ofstream out{tmpini2};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "one=55" << std::endl;
+        out << "one=55" << '\n';
-        out << "three=4" << std::endl;
+        out << "three=4" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1063,8 +1063,8 @@ TEST_CASE_METHOD(TApp, "IniOverwrite", "[config]") {
     TempFile tmpini{"TestIniTmp.ini"};
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
     }
 
     std::string orig = "filename_not_exist.ini";
@@ -1088,9 +1088,9 @@ TEST_CASE_METHOD(TApp, "IniRequired", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1131,9 +1131,9 @@ TEST_CASE_METHOD(TApp, "IniInlineComment", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99 ; this is a two" << std::endl;
+        out << "two=99 ; this is a two" << '\n';
-        out << "three=3; this is a three" << std::endl;
+        out << "three=3; this is a three" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1173,9 +1173,9 @@ TEST_CASE_METHOD(TApp, "TomlInlineComment", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99 # this is a two" << std::endl;
+        out << "two=99 # this is a two" << '\n';
-        out << "three=3# this is a three" << std::endl;
+        out << "three=3# this is a three" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1215,12 +1215,12 @@ TEST_CASE_METHOD(TApp, "TomlDocStringComment", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
-        out << R"(""")" << std::endl;
+        out << R"(""")" << '\n';
-        out << "one=35" << std::endl;
+        out << "one=35" << '\n';
-        out << R"(""")" << std::endl;
+        out << R"(""")" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1242,12 +1242,12 @@ TEST_CASE_METHOD(TApp, "TomlDocStringComment2", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "'''" << std::endl;
+        out << "'''" << '\n';
-        out << "one=35" << std::endl;
+        out << "one=35" << '\n';
-        out << "last comment line three=6 '''" << std::endl;
+        out << "last comment line three=6 '''" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1269,11 +1269,11 @@ TEST_CASE_METHOD(TApp, "TomlDocStringComment3", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=99" << std::endl;
+        out << "two=99" << '\n';
-        out << "three=3" << std::endl;
+        out << "three=3" << '\n';
-        out << "'''" << std::endl;
+        out << "'''" << '\n';
-        out << "one=35" << std::endl;
+        out << "one=35" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1318,9 +1318,9 @@ TEST_CASE_METHOD(TApp, "IniVector", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=2 3" << std::endl;
+        out << "two=2 3" << '\n';
-        out << "three=1 2 3" << std::endl;
+        out << "three=1 2 3" << '\n';
     }
 
     std::vector<int> two, three;
@@ -1519,11 +1519,11 @@ TEST_CASE_METHOD(TApp, "IniLayered", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "subsubcom.val=3" << std::endl;
+        out << "subsubcom.val=3" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1551,11 +1551,11 @@ TEST_CASE_METHOD(TApp, "IniLayeredStream", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "subsubcom.val=3" << std::endl;
+        out << "subsubcom.val=3" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1584,12 +1584,12 @@ TEST_CASE_METHOD(TApp, "IniLayeredDotSection", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "[subcom.subsubcom]" << std::endl;
+        out << "[subcom.subsubcom]" << '\n';
-        out << "val=3" << std::endl;
+        out << "val=3" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1623,12 +1623,12 @@ TEST_CASE_METHOD(TApp, "IniLayeredDotSectionInQuotes", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "['subcom']" << std::endl;
+        out << "['subcom']" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "['subcom'.\"subsubcom\"]" << std::endl;
+        out << "['subcom'.\"subsubcom\"]" << '\n';
-        out << "val=3" << std::endl;
+        out << "val=3" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1662,12 +1662,12 @@ TEST_CASE_METHOD(TApp, "IniLayeredCustomSectionSeparator", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "[subcom|subsubcom]" << std::endl;
+        out << "[subcom|subsubcom]" << '\n';
-        out << "val=3" << std::endl;
+        out << "val=3" << '\n';
     }
     app.get_config_formatter_base()->parentSeparator('|');
     int one{0}, two{0}, three{0};
@@ -1695,10 +1695,10 @@ TEST_CASE_METHOD(TApp, "IniLayeredOptionGroupAlias", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[ogroup]" << std::endl;
+        out << "[ogroup]" << '\n';
-        out << "val2=2" << std::endl;
+        out << "val2=2" << '\n';
     }
     int one{0}, two{0};
     app.add_option("--val", one);
@@ -1719,11 +1719,11 @@ TEST_CASE_METHOD(TApp, "IniSubcommandConfigurable", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "subsubcom.val=3" << std::endl;
+        out << "subsubcom.val=3" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1753,11 +1753,11 @@ TEST_CASE_METHOD(TApp, "IniSubcommandConfigurableInQuotes", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "\"subsubcom\".'val'=3" << std::endl;
+        out << "\"subsubcom\".'val'=3" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1787,11 +1787,11 @@ TEST_CASE_METHOD(TApp, "IniSubcommandConfigurableInQuotesAlias", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << R"("sub\tsub\t.com".'val'=3)" << std::endl;
+        out << R"("sub\tsub\t.com".'val'=3)" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1821,11 +1821,11 @@ TEST_CASE_METHOD(TApp, "IniSubcommandConfigurableInQuotesAliasWithEquals", "[con
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << R"("sub=sub=.com".'val'=3)" << std::endl;
+        out << R"("sub=sub=.com".'val'=3)" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1855,11 +1855,11 @@ TEST_CASE_METHOD(TApp, "IniSubcommandConfigurableInQuotesAliasWithComment", "[co
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << R"("sub#sub;.com".'val'=3)" << std::endl;
+        out << R"("sub#sub;.com".'val'=3)" << '\n';
     }
 
     int one{0}, two{0}, three{0};
@@ -1885,11 +1885,11 @@ TEST_CASE_METHOD(TApp, "IniSubcommandConfigurablePreParse", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "subsubcom.val=3" << std::endl;
+        out << "subsubcom.val=3" << '\n';
     }
 
     int one{0}, two{0}, three{0}, four{0};
@@ -1927,11 +1927,11 @@ TEST_CASE_METHOD(TApp, "IniSection", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[config]" << std::endl;
+        out << "[config]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "subsubcom.val=3" << std::endl;
+        out << "subsubcom.val=3" << '\n';
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
     }
 
     int val{0};
@@ -1951,11 +1951,11 @@ TEST_CASE_METHOD(TApp, "IniSection2", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[config]" << std::endl;
+        out << "[config]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "subsubcom.val=3" << std::endl;
+        out << "subsubcom.val=3" << '\n';
     }
 
     int val{0};
@@ -1975,11 +1975,11 @@ TEST_CASE_METHOD(TApp, "jsonLikeParsing", "[config]") {
 
     {
         std::ofstream out{tmpjson};
-        out << "{" << std::endl;
+        out << "{" << '\n';
-        out << "\"val\":1," << std::endl;
+        out << "\"val\":1," << '\n';
-        out << R"("val2":"test",)" << std::endl;
+        out << R"("val2":"test",)" << '\n';
-        out << "\"flag\":true" << std::endl;
+        out << "\"flag\":true" << '\n';
-        out << "}" << std::endl;
+        out << "}" << '\n';
     }
 
     int val{0};
@@ -2006,17 +2006,17 @@ TEST_CASE_METHOD(TApp, "TomlSectionNumber", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[[config]]" << std::endl;
+        out << "[[config]]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "subsubcom.val=3" << std::endl;
+        out << "subsubcom.val=3" << '\n';
-        out << "[[config]]" << std::endl;
+        out << "[[config]]" << '\n';
-        out << "val=4" << std::endl;
+        out << "val=4" << '\n';
-        out << "subsubcom.val=3" << std::endl;
+        out << "subsubcom.val=3" << '\n';
-        out << "[[config]]" << std::endl;
+        out << "[[config]]" << '\n';
-        out << "val=6" << std::endl;
+        out << "val=6" << '\n';
-        out << "subsubcom.val=3" << std::endl;
+        out << "subsubcom.val=3" << '\n';
     }
 
     int val{0};
@@ -2050,12 +2050,12 @@ TEST_CASE_METHOD(TApp, "IniSubcommandConfigurableParseComplete", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "[subcom.subsubcom]" << std::endl;
+        out << "[subcom.subsubcom]" << '\n';
-        out << "val=3" << std::endl;
+        out << "val=3" << '\n';
     }
 
     int one{0}, two{0}, three{0}, four{0};
@@ -2095,14 +2095,14 @@ TEST_CASE_METHOD(TApp, "IniSubcommandMultipleSections", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
-        out << "[subcom]" << std::endl;
+        out << "[subcom]" << '\n';
-        out << "val=2" << std::endl;
+        out << "val=2" << '\n';
-        out << "[subcom.subsubcom]" << std::endl;
+        out << "[subcom.subsubcom]" << '\n';
-        out << "val=3" << std::endl;
+        out << "val=3" << '\n';
-        out << "[subcom2]" << std::endl;
+        out << "[subcom2]" << '\n';
-        out << "val=4" << std::endl;
+        out << "val=4" << '\n';
     }
 
     int one{0}, two{0}, three{0}, four{0};
@@ -2143,9 +2143,9 @@ TEST_CASE_METHOD(TApp, "DuplicateSubcommandCallbacks", "[config]") {
 
     {
         std::ofstream out{tmptoml};
-        out << "[[foo]]" << std::endl;
+        out << "[[foo]]" << '\n';
-        out << "[[foo]]" << std::endl;
+        out << "[[foo]]" << '\n';
-        out << "[[foo]]" << std::endl;
+        out << "[[foo]]" << '\n';
     }
 
     auto *foo = app.add_subcommand("foo");
@@ -2167,7 +2167,7 @@ TEST_CASE_METHOD(TApp, "SubcommandCallbackSingle", "[config]") {
 
     {
         std::ofstream out{tmptoml};
-        out << "[foo]" << std::endl;
+        out << "[foo]" << '\n';
     }
     int count{0};
     auto *foo = app.add_subcommand("foo");
@@ -2186,8 +2186,8 @@ TEST_CASE_METHOD(TApp, "IniFailure", "[config]") {
     app.allow_config_extras(false);
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
     }
 
     CHECK_THROWS_AS(run(), CLI::ConfigError);
@@ -2203,8 +2203,8 @@ TEST_CASE_METHOD(TApp, "IniConfigurable", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -2221,8 +2221,8 @@ TEST_CASE_METHOD(TApp, "IniNotConfigurable", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
     }
 
     CHECK_THROWS_AS(run(), CLI::ConfigError);
@@ -2240,8 +2240,8 @@ TEST_CASE_METHOD(TApp, "IniFlagDisableOverrideFlagArray", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=[1,true,false,true]" << std::endl;
+        out << "val=[1,true,false,true]" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -2258,8 +2258,8 @@ TEST_CASE_METHOD(TApp, "IniFlagInvalidDisableOverrideFlagArray", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "val=[1,true,false,not_valid]" << std::endl;
+        out << "val=[1,true,false,not_valid]" << '\n';
     }
 
     CHECK_THROWS_AS(run(), CLI::InvalidError);
@@ -2274,8 +2274,8 @@ TEST_CASE_METHOD(TApp, "IniSubFailure", "[config]") {
     app.allow_config_extras(false);
     {
         std::ofstream out{tmpini};
-        out << "[other]" << std::endl;
+        out << "[other]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
     }
 
     CHECK_THROWS_AS(run(), CLI::ConfigError);
@@ -2289,8 +2289,8 @@ TEST_CASE_METHOD(TApp, "IniNoSubFailure", "[config]") {
     app.allow_config_extras(CLI::config_extras_mode::error);
     {
         std::ofstream out{tmpini};
-        out << "[other]" << std::endl;
+        out << "[other]" << '\n';
-        out << "val=1" << std::endl;
+        out << "val=1" << '\n';
     }
 
     CHECK_THROWS_AS(run(), CLI::ConfigError);
@@ -2305,7 +2305,7 @@ TEST_CASE_METHOD(TApp, "IniFlagConvertFailure", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "flag=moobook" << std::endl;
+        out << "flag=moobook" << '\n';
     }
     run();
     bool result{false};
@@ -2326,7 +2326,7 @@ TEST_CASE_METHOD(TApp, "IniFlagNumbers", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "flag=3" << std::endl;
+        out << "flag=3" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -2344,7 +2344,7 @@ TEST_CASE_METHOD(TApp, "IniFlagDual", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "flag=1 1" << std::endl;
+        out << "flag=1 1" << '\n';
     }
 
     CHECK_THROWS_AS(run(), CLI::ConversionError);
@@ -2361,7 +2361,7 @@ TEST_CASE_METHOD(TApp, "IniVectorMax", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "vec=[a,b,c]" << std::endl;
+        out << "vec=[a,b,c]" << '\n';
     }
 
     CHECK_THROWS_AS(run(), CLI::ArgumentMismatch);
@@ -2377,7 +2377,7 @@ TEST_CASE_METHOD(TApp, "IniShort", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "f=3" << std::endl;
+        out << "f=3" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -2394,7 +2394,7 @@ TEST_CASE_METHOD(TApp, "IniShortQuote1", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "\"f\"=3" << std::endl;
+        out << "\"f\"=3" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -2411,7 +2411,7 @@ TEST_CASE_METHOD(TApp, "IniShortQuote2", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "'f'=3" << std::endl;
+        out << "'f'=3" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -2428,7 +2428,7 @@ TEST_CASE_METHOD(TApp, "IniShortQuote3", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "`f`=3" << std::endl;
+        out << "`f`=3" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -2445,7 +2445,7 @@ TEST_CASE_METHOD(TApp, "IniDefaultPath", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "f=3" << std::endl;
+        out << "f=3" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -2464,7 +2464,7 @@ TEST_CASE_METHOD(TApp, "IniMultipleDefaultPath", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "f=3" << std::endl;
+        out << "f=3" << '\n';
     }
 
     args = {"--config", "TestIniTmp.ini"};
@@ -2484,7 +2484,7 @@ TEST_CASE_METHOD(TApp, "IniMultipleDefaultPathAlternate", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "f=3" << std::endl;
+        out << "f=3" << '\n';
     }
 
     args = {"--config", "TestIniTmp.ini"};
@@ -2503,7 +2503,7 @@ TEST_CASE_METHOD(TApp, "IniPositional", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "key=3" << std::endl;
+        out << "key=3" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -2520,7 +2520,7 @@ TEST_CASE_METHOD(TApp, "IniEnvironmental", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "CLI11_TEST_ENV_KEY_TMP=3" << std::endl;
+        out << "CLI11_TEST_ENV_KEY_TMP=3" << '\n';
     }
 
     REQUIRE_NOTHROW(run());
@@ -2540,10 +2540,10 @@ TEST_CASE_METHOD(TApp, "IniFlagText", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "flag1=true" << std::endl;
+        out << "flag1=true" << '\n';
-        out << "flag2=on" << std::endl;
+        out << "flag2=on" << '\n';
-        out << "flag3=off" << std::endl;
+        out << "flag3=off" << '\n';
-        out << "flag4=1" << std::endl;
+        out << "flag4=1" << '\n';
     }
 
     run();
@@ -2560,11 +2560,11 @@ TEST_CASE_METHOD(TApp, "IniFlags", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=2" << std::endl;
+        out << "two=2" << '\n';
-        out << "three=true" << std::endl;
+        out << "three=true" << '\n';
-        out << "four=on" << std::endl;
+        out << "four=on" << '\n';
-        out << "five" << std::endl;
+        out << "five" << '\n';
     }
 
     int two{0};
@@ -2588,12 +2588,12 @@ TEST_CASE_METHOD(TApp, "IniFlagsComment", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=2 # comment 1" << std::endl;
+        out << "two=2 # comment 1" << '\n';
-        out << "three=true" << std::endl;
+        out << "three=true" << '\n';
-        out << "four=on #comment 2" << std::endl;
+        out << "four=on #comment 2" << '\n';
-        out << "five #comment 3" << std::endl;
+        out << "five #comment 3" << '\n';
-        out << std::endl;
+        out << '\n';
     }
 
     int two{0};
@@ -2617,12 +2617,12 @@ TEST_CASE_METHOD(TApp, "IniFlagsAltComment", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=2 % comment 1" << std::endl;
+        out << "two=2 % comment 1" << '\n';
-        out << "three=true" << std::endl;
+        out << "three=true" << '\n';
-        out << "four=on %% comment 2" << std::endl;
+        out << "four=on %% comment 2" << '\n';
-        out << "five %= 3" << std::endl;
+        out << "five %= 3" << '\n';
-        out << std::endl;
+        out << '\n';
     }
 
     auto config = app.get_config_formatter_base();
@@ -2648,11 +2648,11 @@ TEST_CASE_METHOD(TApp, "IniFalseFlags", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=-2" << std::endl;
+        out << "two=-2" << '\n';
-        out << "three=false" << std::endl;
+        out << "three=false" << '\n';
-        out << "four=1" << std::endl;
+        out << "four=1" << '\n';
-        out << "five" << std::endl;
+        out << "five" << '\n';
     }
 
     int two{0};
@@ -2676,11 +2676,11 @@ TEST_CASE_METHOD(TApp, "IniFalseFlagsDef", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=2" << std::endl;
+        out << "two=2" << '\n';
-        out << "three=true" << std::endl;
+        out << "three=true" << '\n';
-        out << "four=on" << std::endl;
+        out << "four=on" << '\n';
-        out << "five" << std::endl;
+        out << "five" << '\n';
     }
 
     int two{0};
@@ -2704,10 +2704,10 @@ TEST_CASE_METHOD(TApp, "IniFalseFlagsDefDisableOverrideError", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=2" << std::endl;
+        out << "two=2" << '\n';
-        out << "four=on" << std::endl;
+        out << "four=on" << '\n';
-        out << "five" << std::endl;
+        out << "five" << '\n';
     }
 
     int two{0};
@@ -2725,10 +2725,10 @@ TEST_CASE_METHOD(TApp, "IniFalseFlagsDefDisableOverrideSuccess", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=2" << std::endl;
+        out << "two=2" << '\n';
-        out << "four={}" << std::endl;
+        out << "four={}" << '\n';
-        out << "val=15" << std::endl;
+        out << "val=15" << '\n';
     }
 
     int two{0}, four{0}, val{0};
@@ -2755,20 +2755,20 @@ TEST_CASE_METHOD(TApp, "IniDisableFlagOverride", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=2" << std::endl;
+        out << "two=2" << '\n';
     }
 
     {
         std::ofstream out{tmpini2};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "two=7" << std::endl;
+        out << "two=7" << '\n';
     }
 
     {
         std::ofstream out{tmpini3};
-        out << "[default]" << std::endl;
+        out << "[default]" << '\n';
-        out << "three=true" << std::endl;
+        out << "three=true" << '\n';
     }
 
     int val{0};
@@ -3284,7 +3284,7 @@ TEST_CASE_METHOD(TApp, "StopReadingConfigOnClear", "[config]") {
 
     {
         std::ofstream out{tmpini};
-        out << "volume=1" << std::endl;
+        out << "volume=1" << '\n';
     }
 
     int volume{0};
@@ -3306,7 +3306,7 @@ TEST_CASE_METHOD(TApp, "ConfigWriteReadWrite", "[config]") {
     std::string config1 = app.config_to_str(true, true);
     {
         std::ofstream out{tmpini};
-        out << config1 << std::endl;
+        out << config1 << '\n';
     }
 
     app.set_config("--config", tmpini, "Read an ini file", true);
@@ -3329,7 +3329,7 @@ TEST_CASE_METHOD(TApp, "ConfigWriteReadNegated", "[config]") {
     std::string config1 = app.config_to_str(false, false);
     {
         std::ofstream out{tmpini};
-        out << config1 << std::endl;
+        out << config1 << '\n';
     }
     CHECK_FALSE(flag);
     args.clear();

tests/FuzzFailTest.cpp

@@ -41,8 +41,10 @@ TEST_CASE("app_fail") {
         try {
             app->parse(parseData);
         } catch(const CLI::ParseError & /*e*/) {
+            CHECK(true);
         }
     } catch(const CLI::ConstructionError & /*e*/) {
+        CHECK(true);
     }
 }
 
@@ -50,12 +52,13 @@ TEST_CASE("file_fail") {
     CLI::FuzzApp fuzzdata;
     auto app = fuzzdata.generateApp();
 
-    int index = GENERATE(range(1, 7));
+    int index = GENERATE(range(1, 9));
     auto parseData = loadFailureFile("fuzz_file_fail", index);
     std::stringstream out(parseData);
     try {
         app->parse_from_stream(out);
     } catch(const CLI::ParseError & /*e*/) {
+        CHECK(true);
     }
 }
 

tests/HelpersTest.cpp

@@ -696,7 +696,7 @@ TEST_CASE("Validators: ProgramNameSplit", "[helpers]") {
     TempFile myfile{"program_name1.exe"};
     {
         std::ofstream out{myfile};
-        out << "useless string doesn't matter" << std::endl;
+        out << "useless string doesn't matter" << '\n';
     }
     auto res =
         CLI::detail::split_program_name(std::string("./") + std::string(myfile) + " this is a bunch of extra stuff  ");
@@ -706,7 +706,7 @@ TEST_CASE("Validators: ProgramNameSplit", "[helpers]") {
     TempFile myfile2{"program name1.exe"};
     {
         std::ofstream out{myfile2};
-        out << "useless string doesn't matter" << std::endl;
+        out << "useless string doesn't matter" << '\n';
     }
     res = CLI::detail::split_program_name(std::string("   ") + std::string("./") + std::string(myfile2) +
                                           "      this is a bunch of extra stuff  ");
@@ -972,7 +972,7 @@ TEST_CASE("AppHelper: Ofstream", "[helpers]") {
 
         {
             std::ofstream out{myfile};
-            out << "this is output" << std::endl;
+            out << "this is output" << '\n';
         }
 
         CHECK(CLI::ExistingFile(myfile).empty());

tests/OptionalTest.cpp

@@ -70,13 +70,11 @@ TEST_CASE_METHOD(TApp, "StdOptionalTest", "[optional]") {
 
     args = {"-c", "1"};
     run();
-    CHECK(opt);
+    CHECK((opt && (1 == *opt)));
-    CHECK(1 == *opt);
 
     args = {"--count", "3"};
     run();
-    CHECK(opt);
+    CHECK((opt && (3 == *opt)));
-    CHECK(3 == *opt);
 }
 
 TEST_CASE_METHOD(TApp, "StdOptionalVectorEmptyDirect", "[optional]") {
@@ -91,7 +89,7 @@ TEST_CASE_METHOD(TApp, "StdOptionalVectorEmptyDirect", "[optional]") {
     CHECK(!opt);
     args = {"-v", "1", "4", "5"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
     std::vector<int> expV{1, 4, 5};
     CHECK(expV == *opt);
 }
@@ -125,7 +123,7 @@ TEST_CASE_METHOD(TApp, "StdOptionalUint", "[optional]") {
 
     args = {"-i", "15"};
     run();
-    CHECK(15U == *opt);
+    CHECK((opt && (15U == *opt)));
     static_assert(CLI::detail::classify_object<std::optional<std::uint64_t>>::value ==
                   CLI::detail::object_category::wrapper_value);
 }
@@ -140,13 +138,14 @@ TEST_CASE_METHOD(TApp, "StdOptionalbool", "[optional]") {
 
     args = {"--opt"};
     run();
-    CHECK(opt);
+    CHECK((opt && *opt));
-    CHECK(*opt);
 
     args = {"--no-opt"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
-    CHECK_FALSE(*opt);
+    if(opt) {
+        CHECK_FALSE(*opt);
+    }
     static_assert(CLI::detail::classify_object<std::optional<bool>>::value ==
                   CLI::detail::object_category::wrapper_value);
 }
@@ -186,12 +185,12 @@ TEST_CASE_METHOD(TApp, "BoostOptionalTest", "[optional]") {
 
     args = {"-c", "1"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
     CHECK(1 == *opt);
     opt = {};
     args = {"--count", "3"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
     CHECK(3 == *opt);
 }
 
@@ -203,7 +202,7 @@ TEST_CASE_METHOD(TApp, "BoostOptionalTestZarg", "[optional]") {
 
     args = {"-c", "1"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
     CHECK(1 == *opt);
     opt = {};
     args = {"--count"};
@@ -219,12 +218,12 @@ TEST_CASE_METHOD(TApp, "BoostOptionalint64Test", "[optional]") {
 
     args = {"-c", "1"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
     CHECK(1 == *opt);
     opt = {};
     args = {"--count", "3"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
     CHECK(3 == *opt);
 }
 
@@ -236,12 +235,12 @@ TEST_CASE_METHOD(TApp, "BoostOptionalStringTest", "[optional]") {
 
     args = {"-s", "strval"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
     CHECK("strval" == *opt);
     opt = {};
     args = {"--string", "strv"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
     CHECK("strv" == *opt);
 }
 namespace boost {
@@ -266,13 +265,13 @@ TEST_CASE_METHOD(TApp, "BoostOptionalEnumTest", "[optional]") {
     args = {"-v", "3"};
     run();
     checkOpt = static_cast<bool>(opt);
-    CHECK(checkOpt);
+    REQUIRE(checkOpt);
     CHECK(*opt == eval::val3);
     opt = {};
     args = {"--val", "1"};
     run();
     checkOpt = static_cast<bool>(opt);
-    CHECK(checkOpt);
+    REQUIRE(checkOpt);
     CHECK(*opt == eval::val1);
 }
 
@@ -288,7 +287,7 @@ TEST_CASE_METHOD(TApp, "BoostOptionalVector", "[optional]") {
     args = {"-v", "1", "4", "5"};
     run();
     checkOpt = static_cast<bool>(opt);
-    CHECK(checkOpt);
+    REQUIRE(checkOpt);
     std::vector<int> expV{1, 4, 5};
     CHECK(expV == *opt);
 }
@@ -308,7 +307,7 @@ TEST_CASE_METHOD(TApp, "BoostOptionalVectorEmpty", "[optional]") {
     args = {"-v", "1", "4", "5"};
     run();
     checkOpt = static_cast<bool>(opt);
-    CHECK(checkOpt);
+    REQUIRE(checkOpt);
     std::vector<int> expV{1, 4, 5};
     CHECK(expV == *opt);
 }
@@ -328,7 +327,7 @@ TEST_CASE_METHOD(TApp, "BoostOptionalVectorEmptyDirect", "[optional]") {
     args = {"-v", "1", "4", "5"};
     run();
     checkOpt = static_cast<bool>(opt);
-    CHECK(checkOpt);
+    REQUIRE(checkOpt);
     std::vector<int> expV{1, 4, 5};
     CHECK(expV == *opt);
 }
@@ -344,12 +343,12 @@ TEST_CASE_METHOD(TApp, "BoostOptionalComplexDirect", "[optional]") {
     CHECK(!opt);
     args = {"-c", "1+2j"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
     std::complex<double> val{1, 2};
     CHECK(val == *opt);
     args = {"-c", "3", "-4"};
     run();
-    CHECK(opt);
+    REQUIRE(opt);
     std::complex<double> val2{3, -4};
     CHECK(val2 == *opt);
 }

tests/StringParseTest.cpp

@@ -20,7 +20,7 @@ TEST_CASE_METHOD(TApp, "ExistingExeCheck", "[stringparse]") {
 
     {
         std::ofstream out{tmpexe};
-        out << "useless string doesn't matter" << std::endl;
+        out << "useless string doesn't matter" << '\n';
     }
 
     app.parse(std::string("./") + std::string(tmpexe) +
@@ -42,7 +42,7 @@ TEST_CASE_METHOD(TApp, "ExistingExeCheckWithSpace", "[stringparse]") {
 
     {
         std::ofstream out{tmpexe};
-        out << "useless string doesn't matter" << std::endl;
+        out << "useless string doesn't matter" << '\n';
     }
 
     app.parse(std::string("./") + std::string(tmpexe) +
@@ -66,7 +66,7 @@ TEST_CASE_METHOD(TApp, "ExistingExeCheckWithLotsOfSpace", "[stringparse]") {
 
     {
         std::ofstream out{tmpexe};
-        out << "useless string doesn't matter" << std::endl;
+        out << "useless string doesn't matter" << '\n';
     }
 
     app.parse(std::string("./") + std::string(tmpexe) +

tests/TimerTest.cpp

@@ -63,6 +63,6 @@ TEST_CASE("Timer: PrintTimer", "[timer]") {
 TEST_CASE("Timer: TimeItTimer", "[timer]") {
     CLI::Timer timer;
     std::string output = timer.time_it([]() { std::this_thread::sleep_for(std::chrono::milliseconds(10)); }, .1);
-    std::cout << output << std::endl;
+    std::cout << output << '\n';
     CHECK_THAT(output, Contains("ms"));
 }

tests/fuzzFail/fuzz_file_fail7

@@ -0,0 +1 @@
+--vdtr5=[|

tests/fuzzFail/fuzz_file_fail8

@@ -0,0 +1 @@
+[ÏqÏq[]1."È"\".saopt1[[]1."È"\".saopt1[]

tests/informational.cpp

@@ -52,5 +52,5 @@ int main() {
     std::cout << "  boost::optional support active\n";
 #endif
 
-    std::cout << std::endl;
+    std::cout << '\n';
 }