InputCommon: fix serialization of control expression with line breaks

The control expression editor allows line breaks, but the serialization was
losing anything after the first line break (/r /n).
Instead of opting to encode them and decode them on serialization
(which I tried but was not safe, as it would lose /n written in the string by users),
I opted to replace them with a space.

Source/Core/Common/StringUtil.cpp

@@ -219,7 +219,7 @@ std::string ArrayToString(const u8* data, u32 size, int line_len, bool spaces)
   return oss.str();
 }
 
-// Turns "  hello " into "hello". Also handles tabs.
+// Turns "\n\r\t hello " into "hello" (trims at the start and end but not inside).
 std::string_view StripSpaces(std::string_view str)
 {
   const size_t s = str.find_first_not_of(" \t\r\n");
@@ -241,6 +241,13 @@ std::string_view StripQuotes(std::string_view s)
     return s;
 }
 
+// Turns "\n\rhello" into "  hello".
+void ReplaceBreaksWithSpaces(std::string& str)
+{
+  std::replace(str.begin(), str.end(), '\r', ' ');
+  std::replace(str.begin(), str.end(), '\n', ' ');
+}
+
 bool TryParse(const std::string& str, bool* const output)
 {
   float value;

Source/Core/Common/StringUtil.h

@@ -52,6 +52,8 @@ std::string_view StripQuotes(std::string_view s);
 
 std::string ReplaceAll(std::string result, std::string_view src, std::string_view dest);
 
+void ReplaceBreaksWithSpaces(std::string& str);
+
 bool TryParse(const std::string& str, bool* output);
 
 template <typename T, std::enable_if_t<std::is_integral_v<T> || std::is_enum_v<T>>* = nullptr>

Source/Core/InputCommon/ControllerEmu/ControlGroup/ControlGroup.cpp

@@ -117,7 +117,10 @@ void ControlGroup::SaveConfig(IniFile::Section* sec, const std::string& defdev,
   for (auto& c : controls)
   {
     // control expression
-    sec->Set(group + c->name, c->control_ref->GetExpression(), "");
+    std::string expression = c->control_ref->GetExpression();
+    // We can't save line breaks in a single line config. Restoring them is too complicated.
+    ReplaceBreaksWithSpaces(expression);
+    sec->Set(group + c->name, expression, "");
 
     // range
     sec->Set(group + c->name + "/Range", c->control_ref->range * 100.0, 100.0);
@@ -135,7 +138,9 @@ void ControlGroup::SaveConfig(IniFile::Section* sec, const std::string& defdev,
     }
     else
     {
-      sec->Set(base + name, ext->GetSelectionSetting().GetInputReference().GetExpression(), "None");
+      std::string expression = ext->GetSelectionSetting().GetInputReference().GetExpression();
+      ReplaceBreaksWithSpaces(expression);
+      sec->Set(base + name, expression, "None");
     }
 
     for (auto& ai : ext->GetAttachmentList())

Source/Core/InputCommon/ControllerEmu/Setting/NumericSetting.h

@@ -113,9 +113,16 @@ class NumericSetting final : public NumericSettingBase
   void SaveToIni(IniFile::Section& section, const std::string& group_name) const override
   {
     if (IsSimpleValue())
+    {
       section.Set(group_name + m_details.ini_name, GetValue(), m_default_value);
+    }
     else
-      section.Set(group_name + m_details.ini_name, m_value.m_input.GetExpression(), "");
+    {
+      // We can't save line breaks in a single line config. Restoring them is too complicated.
+      std::string expression = m_value.m_input.GetExpression();
+      ReplaceBreaksWithSpaces(expression);
+      section.Set(group_name + m_details.ini_name, expression, "");
+    }
   }
 
   bool IsSimpleValue() const override { return m_value.IsSimpleValue(); }