From d363be0eef4bf07f024b16d6cc343f6f2215cb17 Mon Sep 17 00:00:00 2001
From: lisyarus <lisyarus@gmail.com>
Date: Sat, 21 Mar 2026 22:09:33 +0300
Subject: [PATCH] Replace some usages of ostringstream with std::format

---
 libs/ast/source/type_check.cpp   | 10 ++--------
 libs/interpreter/source/eval.cpp | 19 ++++---------------
 plans.txt                        |  2 +-
 3 files changed, 7 insertions(+), 24 deletions(-)

diff --git a/libs/ast/source/type_check.cpp b/libs/ast/source/type_check.cpp
index bb68879..5dca68b 100644
--- a/libs/ast/source/type_check.cpp
+++ b/libs/ast/source/type_check.cpp
@@ -571,11 +571,7 @@ namespace pslang::ast
 						if (!node.arguments.empty())
 						{
 							if (node.arguments.size() != struct_node.fields.size())
-							{
-								std::ostringstream os;
-								os << "Cannot create struct " << named_type->name << ": expected " << struct_node.fields.size() << " arguments, but got " << node.arguments.size();
-								throw type_error(os.str(), node.location);
-							}
+								throw type_error(std::format("Cannot create struct {}: expected {} arguments, but got {}", named_type->name, struct_node.fields.size(), node.arguments.size()), node.location);
 
 							for (std::size_t i = 0; i < node.arguments.size(); ++i)
 							{
@@ -688,9 +684,7 @@ namespace pslang::ast
 					}
 				}
 
-				std::ostringstream os;
-				os << "Struct \"" << named_type->name << "\" has no field named \"" << node.field_name << "\"";
-				throw type_error(os.str(), node.location);
+				throw type_error(std::format("Struct \"{}\" has no field named \"{}\"", named_type->name, node.field_name), node.location);
 			}
 
 			void apply(expression_ptr const & node)
diff --git a/libs/interpreter/source/eval.cpp b/libs/interpreter/source/eval.cpp
index 14129b5..52d7f12 100644
--- a/libs/interpreter/source/eval.cpp
+++ b/libs/interpreter/source/eval.cpp
@@ -8,6 +8,7 @@
 
 #include <sstream>
 #include <optional>
+#include <format>
 
 namespace pslang::interpreter
 {
@@ -67,21 +68,13 @@ namespace pslang::interpreter
 			if (index_unsigned)
 			{
 				if (*index_unsigned >= size)
-				{
-					std::ostringstream os;
-					os << "Array index " << *index_unsigned << " out of bounds " << size;
-					throw runtime_error(os.str(), location);
-				}
+					throw runtime_error(std::format("Array index {} out of bounds {}", *index_unsigned, size), location);
 				return *index_unsigned;
 			}
 			else // if (index_signed)
 			{
 				if (*index_signed < 0 || *index_signed >= size)
-				{
-					std::ostringstream os;
-					os << "Array index " << *index_signed << " out of bounds " << size;
-					throw runtime_error(os.str(), location);
-				}
+					throw runtime_error(std::format("Array index {} out of bounds {}", *index_signed, size), location);
 				return *index_signed;
 			}
 		}
@@ -522,11 +515,7 @@ namespace pslang::interpreter
 				if (fcommon)
 				{
 					if (fcommon->arguments.size() != function_call.arguments.size())
-					{
-						std::ostringstream os;
-						os << "Cannot call function: expected " << fcommon->arguments.size() << " arguments, got " << function_call.arguments.size();
-						throw internal_error(os.str(), function_call.location);
-					}
+						throw internal_error(std::format("Cannot call function: expected {} arguments, got {}", fcommon->arguments.size(), function_call.arguments.size()), function_call.location);
 
 					std::vector<value> args;
 					for (auto const & expression : function_call.arguments)
diff --git a/plans.txt b/plans.txt
index c31087b..49f3cbf 100644
--- a/plans.txt
+++ b/plans.txt
@@ -41,6 +41,6 @@ General backlog:
 * Empty array expression
 * Calling functions as methods
 * Replace std::runtime_error with appropriate custom exception types
-* Replace std::ostringstream with std::format
+* Replace std::ostringstream with std::format (need support for std::format in type/ast printing)
 * TEST COVERAGE!!!
 * Separate actual AST from pre-AST (the one before indentation & scoping is resolved)