From 8da32c25c5322d389b4e593e9f9b8168b7ecd0ce Mon Sep 17 00:00:00 2001
From: sofia <sofia@teascade.net>
Date: Mon, 21 Jul 2025 10:07:56 +0300
Subject: [PATCH] Make borrows work as function parameters as well

---
 reid/src/ast/mod.rs       |  1 +
 reid/src/ast/parse.rs     |  4 ++++
 reid/src/ast/process.rs   |  5 ++++-
 reid/src/codegen.rs       |  2 +-
 reid/src/mir/typecheck.rs |  2 +-
 reid_src/borrow_hard.reid | 13 +++++++++++++
 6 files changed, 24 insertions(+), 3 deletions(-)
 create mode 100644 reid_src/borrow_hard.reid

diff --git a/reid/src/ast/mod.rs b/reid/src/ast/mod.rs
index 56b5a2f..665f286 100644
--- a/reid/src/ast/mod.rs
+++ b/reid/src/ast/mod.rs
@@ -27,6 +27,7 @@ pub enum TypeKind {
     String,
     Array(Box<TypeKind>, u64),
     Custom(String),
+    Borrow(Box<TypeKind>),
 }
 
 #[derive(Debug, Clone)]
diff --git a/reid/src/ast/parse.rs b/reid/src/ast/parse.rs
index 26f374d..be2d6ab 100644
--- a/reid/src/ast/parse.rs
+++ b/reid/src/ast/parse.rs
@@ -24,6 +24,10 @@ impl Parse for Type {
             };
             stream.expect(Token::BracketClose)?;
             TypeKind::Array(Box::new(inner.0), length)
+        } else if let Some(Token::Et) = stream.peek() {
+            stream.expect(Token::Et)?;
+            let inner = stream.parse::<Type>()?;
+            TypeKind::Borrow(Box::new(inner.0))
         } else {
             if let Some(Token::Identifier(ident)) = stream.next() {
                 match &*ident {
diff --git a/reid/src/ast/process.rs b/reid/src/ast/process.rs
index a871ffa..3b872b5 100644
--- a/reid/src/ast/process.rs
+++ b/reid/src/ast/process.rs
@@ -1,4 +1,4 @@
-use std::path::PathBuf;
+use std::{path::PathBuf, process};
 
 use crate::{
     ast::{self},
@@ -287,6 +287,9 @@ impl From<ast::TypeKind> for mir::TypeKind {
             }
             ast::TypeKind::String => mir::TypeKind::StringPtr,
             ast::TypeKind::Custom(name) => mir::TypeKind::CustomType(name.clone()),
+            ast::TypeKind::Borrow(type_kind) => {
+                mir::TypeKind::Borrow(Box::new(mir::TypeKind::from(*type_kind.clone())))
+            }
         }
     }
 }
diff --git a/reid/src/codegen.rs b/reid/src/codegen.rs
index 4af97b9..6343017 100644
--- a/reid/src/codegen.rs
+++ b/reid/src/codegen.rs
@@ -360,7 +360,7 @@ impl mir::Module {
                 stack_values.insert(
                     p_name.clone(),
                     StackValue(
-                        StackValueKind::Immutable(alloca),
+                        StackValueKind::Mutable(alloca),
                         TypeKind::Ptr(Box::new(p_ty.clone())),
                     ),
                 );
diff --git a/reid/src/mir/typecheck.rs b/reid/src/mir/typecheck.rs
index b407b2e..1d5232e 100644
--- a/reid/src/mir/typecheck.rs
+++ b/reid/src/mir/typecheck.rs
@@ -162,7 +162,7 @@ impl FunctionDefinition {
                     param.0.clone(),
                     ScopeVariable {
                         ty: param_t,
-                        mutable: false,
+                        mutable: true,
                     },
                 )
                 .or(Err(ErrorKind::VariableAlreadyDefined(param.0.clone())));
diff --git a/reid_src/borrow_hard.reid b/reid_src/borrow_hard.reid
new file mode 100644
index 0000000..87545b5
--- /dev/null
+++ b/reid_src/borrow_hard.reid
@@ -0,0 +1,13 @@
+// Arithmetic, function calls and imports!
+
+fn changer(param: &u32) {
+  *param = 17;
+}
+
+fn main() -> u32 {
+  let mut value = 6;
+
+  changer(&value);
+
+  return value;
+}