Add multiline ini comments

include/CLI/App.hpp

@@ -847,7 +847,7 @@ class App {
                         if(out.tellp() != 0) {
                             out << std::endl;
                         }
-                        out << "; " << opt->get_description() << std::endl;
+                        out << "; " << detail::fix_newlines("; ", opt->get_description()) << std::endl;
                     }
                     out << name << "=" << value << std::endl;
                 }

include/CLI/StringTools.hpp

@@ -187,5 +187,21 @@ inline std::vector<std::string> split_up(std::string str) {
     return output;
 }
 
+/// Add a leader to the beginning of all new lines (nothing is added
+/// at the start of the first line). `"; "` would be for ini files
+///
+/// Can't use Regex, or this would be a subs.
+inline std::string fix_newlines(std::string leader, std::string input) {
+    std::string::size_type n = 0;
+    while(n != std::string::npos && n < input.size()) {
+        n = input.find('\n', n);
+        if(n != std::string::npos) {
+            input = input.substr(0, n + 1) + leader + input.substr(n + 1);
+            n += leader.size();
+        }
+    }
+    return input;
+}
+
 } // namespace detail
 } // namespace CLI

tests/HelpersTest.cpp

@@ -359,3 +359,17 @@ TEST(Types, LexicalCastString) {
     CLI::detail::lexical_cast(input, output);
     EXPECT_EQ(input, output);
 }
+
+TEST(FixNewLines, BasicCheck) {
+    std::string input = "one\ntwo";
+    std::string output = "one\n; two";
+    std::string result = CLI::detail::fix_newlines("; ", input);
+    EXPECT_EQ(result, output);
+}
+
+TEST(FixNewLines, EdgesCheck) {
+    std::string input = "\none\ntwo\n";
+    std::string output = "\n; one\n; two\n; ";
+    std::string result = CLI::detail::fix_newlines("; ", input);
+    EXPECT_EQ(result, output);
+}

tests/IniTest.cpp

@@ -600,6 +600,19 @@ TEST_F(TApp, IniOutputShortDoubleDescription) {
     EXPECT_EQ(str, "; " + description1 + "\n" + flag1 + "=false\n\n; " + description2 + "\n" + flag2 + "=false\n");
 }
 
+TEST_F(TApp, IniOutputMultiLineDescription) {
+    std::string flag = "some_flag";
+    std::string description = "Some short description.\nThat has lines.";
+    app.add_flag("--" + flag, description);
+
+    run();
+
+    std::string str = app.config_to_str(true, "", true);
+    EXPECT_THAT(str, HasSubstr("; Some short description.\n"));
+    EXPECT_THAT(str, HasSubstr("; That has lines.\n"));
+    EXPECT_THAT(str, HasSubstr(flag + "=false\n"));
+}
+
 TEST_F(TApp, IniOutputVector) {
 
     std::vector<int> v;