rustmaker: Use OString literals (loplugin:ostr)

This fixes clang plugin errors like the following
seen in an --enable-rust-uno build:

    .../libreoffice/codemaker/source/rustmaker/rustproduce.cxx:1063:16: error: use a _ostr user-defined string literal instead of constructing an instance of 'OString' from an ordinary string literal [loplugin:ostr]
     1063 |         return "u8";
          |                ^~~~

Change-Id: I5891641b80b46e19f1ceb401e48b6a8fb0286e58
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/190848
Tested-by: Jenkins
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>

codemaker/source/rustmaker/cpproduce.cxx

@@ -1104,7 +1104,7 @@ OString CppProducer::getCFunctionPrefix(std::string_view unoName)
 {
     // Convert com.sun.star.lang.XMain to com__sun__star__lang__XMain for function names
     OString temp(unoName);
-    return temp.replaceAll(".", "__");
+    return temp.replaceAll("."_ostr, "__"_ostr);
 }
 
 OString CppProducer::getMethodReturnType(std::u16string_view returnType) const
@@ -1120,13 +1120,13 @@ OString CppProducer::getMethodDefaultReturn(std::u16string_view returnType) cons
 
     // Handle void vs non-void return types properly
     if (resolvedType == u"void")
-        return ""; // void methods don't return anything
+        return ""_ostr; // void methods don't return anything
 
     // Return appropriate default values for different types
     if (resolvedType == u"double")
-        return "0.0";
+        return "0.0"_ostr;
     else if (resolvedType == u"float")
-        return "0.0f";
+        return "0.0f"_ostr;
     else if (resolvedType == u"sal_Int32" || resolvedType == u"long" || resolvedType == u"sal_Int16"
              || resolvedType == u"short" || resolvedType == u"sal_Int8" || resolvedType == u"byte"
              || resolvedType == u"sal_uInt8" || resolvedType == u"sal_uInt16"
@@ -1134,9 +1134,9 @@ OString CppProducer::getMethodDefaultReturn(std::u16string_view returnType) cons
              || resolvedType == u"sal_uInt64" || resolvedType == u"sal_Unicode"
              || resolvedType == u"unsigned short" || resolvedType == u"unsigned long"
              || resolvedType == u"unsigned hyper" || resolvedType == u"hyper")
-        return "0";
+        return "0"_ostr;
     else if (resolvedType == u"sal_Bool" || resolvedType == u"boolean")
-        return "false";
+        return "false"_ostr;
     else
     {
         // Check if it's an enum type
@@ -1154,11 +1154,11 @@ OString CppProducer::getMethodDefaultReturn(std::u16string_view returnType) cons
         else if (isUnoType(resolvedType) && isUnoStruct(resolvedType))
         {
             // Return empty struct for struct types
-            return OString("{}"); // Empty struct literal
+            return "{}"_ostr; // Empty struct literal
         }
         else
         {
-            return "nullptr"; // For pointer/interface/any types
+            return "nullptr"_ostr; // For pointer/interface/any types
         }
     }
 }
@@ -2485,25 +2485,25 @@ OString CppProducer::convertBasicType(const OString& typeName) const
 
     // Convert UNO primitive types to C++ types
     if (result == "long")
-        result = "sal_Int32";
+        result = "sal_Int32"_ostr;
     else if (result == "short")
-        result = "sal_Int16";
+        result = "sal_Int16"_ostr;
     else if (result == "byte")
-        result = "sal_Int8";
+        result = "sal_Int8"_ostr;
     else if (result == "boolean")
-        result = "sal_Bool";
+        result = "sal_Bool"_ostr;
     else if (result == "double")
-        result = "double";
+        result = "double"_ostr;
     else if (result == "float")
-        result = "float";
+        result = "float"_ostr;
     else if (result == "string")
-        result = "OUString";
+        result = "OUString"_ostr;
     else if (result == "any")
-        result = "Any";
+        result = "Any"_ostr;
     else if (result.indexOf('.') != -1)
     {
         // For UNO types with namespace, convert dots to double colons
-        result = result.replaceAll(".", "::");
+        result = result.replaceAll("."_ostr, "::"_ostr);
     }
 
     return result;

codemaker/source/rustmaker/rustproduce.cxx

@@ -1060,44 +1060,44 @@ OString RustProducer::getRustWrapperTypeName(std::u16string_view unoType) const
 
     // Handle primitive types
     if (rustType == "boolean")
-        return "u8";
+        return "u8"_ostr;
     if (rustType == "byte")
-        return "i8";
+        return "i8"_ostr;
     if (rustType == "short")
-        return "i16";
+        return "i16"_ostr;
     if (rustType == "unsigned short")
-        return "u16";
+        return "u16"_ostr;
     if (rustType == "long")
-        return "i32";
+        return "i32"_ostr;
     if (rustType == "unsigned long")
-        return "u32";
+        return "u32"_ostr;
     if (rustType == "hyper")
-        return "i64";
+        return "i64"_ostr;
     if (rustType == "unsigned hyper")
-        return "u64";
+        return "u64"_ostr;
     if (rustType == "float")
-        return "f32";
+        return "f32"_ostr;
     if (rustType == "double")
-        return "f64";
+        return "f64"_ostr;
     if (rustType == "char")
-        return "u16";
+        return "u16"_ostr;
 
     // Handle special UNO types
     if (rustType == "string")
-        return "Option<crate::core::OUString>";
+        return "Option<crate::core::OUString>"_ostr;
     if (rustType == "any" || rustType == "com.sun.star.uno.Any")
-        return "Option<crate::core::Any>";
+        return "Option<crate::core::Any>"_ostr;
 
     // Handle sequence types (arrays) - return raw pointer for now
     if (rustType.startsWith("[]"))
     {
-        return "*mut c_void";
+        return "*mut c_void"_ostr;
     }
 
     // Handle template types like Pair<T,U> - return raw pointer for now to avoid parsing issues
     if (rustType.indexOf('<') != -1 && rustType.indexOf('>') != -1)
     {
-        return "*mut c_void";
+        return "*mut c_void"_ostr;
     }
 
     // Handle generated UNO types (interface, struct, enum)
@@ -1106,7 +1106,7 @@ OString RustProducer::getRustWrapperTypeName(std::u16string_view unoType) const
         // Skip types that look malformed or have invalid characters
         if (rustType.indexOf('[') != -1 || rustType.indexOf('<') != -1)
         {
-            return "*mut c_void";
+            return "*mut c_void"_ostr;
         }
 
         // First resolve typedefs
@@ -1130,7 +1130,7 @@ OString RustProducer::getRustWrapperTypeName(std::u16string_view unoType) const
     }
 
     // Default to raw pointer for unknown types
-    return "*mut c_void";
+    return "*mut c_void"_ostr;
 }
 
 OString RustProducer::resolveTypedef(std::u16string_view unoType) const
@@ -1159,7 +1159,7 @@ OString RustProducer::getRustReturnType(std::u16string_view unoType) const
     // Handle void returns
     if (unoType == u"void")
     {
-        return "()";
+        return "()"_ostr;
     }
 
     // For interfaces, structs, enums - return Option<TypeWrapper> like services
@@ -1169,7 +1169,7 @@ OString RustProducer::getRustReturnType(std::u16string_view unoType) const
         if (rustType.indexOf('.') != -1)
         {
             // Convert dots to :: for module path
-            OString modulePath = rustType.replaceAll(".", "::");
+            OString modulePath = rustType.replaceAll("."_ostr, "::"_ostr);
 
             // Extract simple type name
             sal_Int32 lastDot = rustType.lastIndexOf('.');
@@ -1191,7 +1191,7 @@ OString RustProducer::getRustFFIReturnType(std::u16string_view unoType) const
     // Handle void returns
     if (unoType == u"void")
     {
-        return "()";
+        return "()"_ostr;
     }
 
     // For interfaces, structs, enums - return their opaque handle typedef
@@ -1204,7 +1204,7 @@ OString RustProducer::getRustFFIReturnType(std::u16string_view unoType) const
     }
 
     // For other types (primitives, sequences, etc) - use void*
-    return "*mut c_void";
+    return "*mut c_void"_ostr;
 }
 
 bool RustProducer::isUnoInterface(std::u16string_view typeName) const