add asref check

lib/edlang_check/src/lib.rs

@@ -201,16 +201,28 @@ pub fn lowering_error_to_report(
                 )
                 .finish()
         }
-        LoweringError::NotMutable { span, file_id } => {
+        LoweringError::NotMutable {
+            span,
+            declare_span,
+            file_id,
+        } => {
             let path = session.file_paths[file_id].display().to_string();
-            Report::build(ReportKind::Error, path.clone(), span.lo)
+            let mut report = Report::build(ReportKind::Error, path.clone(), span.lo)
                 .with_code("NotMutable")
                 .with_label(
-                    Label::new((path, span.into()))
-                        .with_message("can't mutate this value because it's not declared mutable")
+                    Label::new((path.clone(), span.into()))
+                        .with_message("can't mutate this variable because it's not mutable")
                         .with_color(colors.next()),
-                )
-                .finish()
+                );
+
+            if let Some(declare_span) = declare_span {
+                report = report.with_label(
+                    Label::new((path, declare_span.into()))
+                        .with_message("variable declared here")
+                        .with_color(colors.next()),
+                );
+            }
+            report.finish()
         }
         LoweringError::NotMutableSelf {
             span,
@@ -232,5 +244,28 @@ pub fn lowering_error_to_report(
                 )
                 .finish()
         }
+        LoweringError::CantTakeMutableBorrow {
+            span,
+            declare_span,
+            file_id,
+        } => {
+            let path = session.file_paths[file_id].display().to_string();
+            let mut report = Report::build(ReportKind::Error, path.clone(), span.lo)
+                .with_code("CantTakeMutableBorrow")
+                .with_label(
+                    Label::new((path.clone(), span.into()))
+                        .with_message("can't take a mutate borrow to this variable because it's not declared mutable")
+                        .with_color(colors.next()),
+                );
+
+            if let Some(declare_span) = declare_span {
+                report = report.with_label(
+                    Label::new((path, declare_span.into()))
+                        .with_message("variable declared here")
+                        .with_color(colors.next()),
+                );
+            }
+            report.finish()
+        }
     }
 }

lib/edlang_driver/tests/programs/if_if_false.ed

@@ -1,6 +1,6 @@
 
 fn main() -> i32 {
-    let foo: i32 = 7;
+    let mut foo: i32 = 7;
 
     if true {
         if false {

lib/edlang_ir/src/lib.rs

@@ -178,6 +178,18 @@ impl Local {
             mutable: false,
         }
     }
+
+    pub fn is_mutable(&self) -> bool {
+        if self.mutable {
+            return true;
+        }
+
+        match self.ty.kind {
+            TypeKind::Ptr(is_mut, _) => is_mut,
+            TypeKind::Ref(is_mut, _) => is_mut,
+            _ => false,
+        }
+    }
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -424,6 +436,19 @@ pub enum RValue {
     Cast(Operand, TypeInfo, Span),
 }
 
+impl RValue {
+    pub fn get_local(&self) -> Option<usize> {
+        match self {
+            RValue::Use(op, _) => op.get_local(),
+            RValue::Ref(_, op, _) => op.get_local(),
+            RValue::BinOp(_, _, _, _) => None,
+            RValue::LogicOp(_, _, _, _) => None,
+            RValue::UnOp(_, _, _) => None,
+            RValue::Cast(op, _, _) => op.get_local(),
+        }
+    }
+}
+
 #[derive(Debug, Clone)]
 pub enum Operand {
     Copy(Place),
@@ -431,6 +456,16 @@ pub enum Operand {
     Constant(ConstData),
 }
 
+impl Operand {
+    pub fn get_local(&self) -> Option<usize> {
+        match self {
+            Operand::Copy(place) => Some(place.local),
+            Operand::Move(place) => Some(place.local),
+            Operand::Constant(_) => None,
+        }
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct Place {
     pub local: usize,

lib/edlang_lowering/src/errors.rs

@@ -71,7 +71,17 @@ pub enum LoweringError {
         file_id: usize,
     },
     #[error("can't mutate this value because it's not declared mutable")]
-    NotMutable { span: Span, file_id: usize },
+    NotMutable {
+        span: Span,
+        declare_span: Option<Span>,
+        file_id: usize,
+    },
+    #[error("can't take a mutable borrow to this value because it's not declared mutable")]
+    CantTakeMutableBorrow {
+        span: Span,
+        declare_span: Option<Span>,
+        file_id: usize,
+    },
     #[error("this method requires a mutable 'self'")]
     NotMutableSelf {
         span: Span,

lib/edlang_lowering/src/lib.rs

@@ -536,6 +536,14 @@ fn lower_assign(builder: &mut BodyBuilder, info: &ast::AssignStmt) -> Result<(),
         kind: ty,
     };
 
+    if !builder.body.locals[place.local].is_mutable() {
+        return Err(LoweringError::NotMutable {
+            span: info.span,
+            declare_span: builder.body.locals[place.local].span,
+            file_id: builder.file_id,
+        });
+    }
+
     for _ in 0..info.deref_times {
         match &path_ty.kind {
             TypeKind::Ptr(is_mut, inner) => {
@@ -687,7 +695,7 @@ fn lower_expr(
             let ty = match ty {
                 TypeKind::Ptr(_, inner) => *inner,
                 TypeKind::Ref(_, inner) => *inner,
-                _ => todo!("proepr error here"),
+                _ => todo!("proper error here"),
             };
 
             (
@@ -706,6 +714,16 @@ fn lower_expr(
             };
             let (mut value, ty, _span) = lower_expr(builder, inner, type_hint)?;
 
+            if let Some(local) = value.get_local() {
+                if *mutable && !builder.body.locals[local].mutable {
+                    return Err(LoweringError::CantTakeMutableBorrow {
+                        span: *as_ref_span,
+                        declare_span: builder.body.locals[local].span,
+                        file_id: builder.file_id,
+                    });
+                }
+            }
+
             // check if its a use directly, to avoid a temporary.
             value = match value {
                 RValue::Use(op, _span) => RValue::Ref(*mutable, op, *as_ref_span),