From b14a62bc34efef8c5d21e480f28ce7028d38d92c Mon Sep 17 00:00:00 2001
From: sofia <sofia@teascade.net>
Date: Sun, 13 Jul 2025 19:39:43 +0300
Subject: [PATCH] Add typechecking for arrays

---
 reid/src/mir/pass.rs          | 11 ++++++++++
 reid/src/mir/typecheck.rs     | 40 +++++++++++++++++++++++++++++++++--
 reid/src/mir/typeinference.rs | 17 +++++++++------
 3 files changed, 60 insertions(+), 8 deletions(-)

diff --git a/reid/src/mir/pass.rs b/reid/src/mir/pass.rs
index 8da3abc..ff1e421 100644
--- a/reid/src/mir/pass.rs
+++ b/reid/src/mir/pass.rs
@@ -2,6 +2,7 @@
 //! passes. Passes can be performed on Reid MIR to e.g. typecheck the code.
 
 use std::collections::HashMap;
+use std::convert::Infallible;
 use std::error::Error as STDError;
 
 use super::*;
@@ -166,6 +167,16 @@ impl<'st, 'sc, TError: STDError + Clone> PassState<'st, 'sc, TError> {
         self.state.ok(result, meta)
     }
 
+    pub fn note_errors<TMeta: Into<Metadata> + Clone>(
+        &mut self,
+        errors: &Vec<TError>,
+        meta: TMeta,
+    ) {
+        for error in errors {
+            self.ok::<_, Infallible>(Err(error.clone()), meta.clone().into());
+        }
+    }
+
     pub fn inner(&mut self) -> PassState<TError> {
         self.inner.push(self.scope.inner());
         let scope = self.inner.last_mut().unwrap();
diff --git a/reid/src/mir/typecheck.rs b/reid/src/mir/typecheck.rs
index 3c48be6..e8d070b 100644
--- a/reid/src/mir/typecheck.rs
+++ b/reid/src/mir/typecheck.rs
@@ -42,6 +42,8 @@ pub enum ErrorKind {
     BranchTypesDiffer(TypeKind, TypeKind),
     #[error("Attempted to index a non-array type of {0}")]
     TriedIndexingNonArray(TypeKind),
+    #[error("Index {0} out of bounds ({1})")]
+    IndexOutOfBounds(u64, u64),
 }
 
 /// Struct used to implement a type-checking pass that can be performed on the
@@ -376,8 +378,42 @@ impl Expression {
                 Ok(collapsed)
             }
             ExprKind::Block(block) => block.typecheck(state, &hints, hint_t),
-            ExprKind::Index(expression, _) => todo!("typechecking for index expression"),
-            ExprKind::Array(expressions) => todo!("typechecking for array expression"),
+            ExprKind::Index(expression, idx) => {
+                let expr_t = expression.typecheck(state, hints, hint_t)?;
+                if let TypeKind::Array(elem_t, len) = expr_t {
+                    if len >= *idx {
+                        return Err(ErrorKind::IndexOutOfBounds(*idx, len));
+                    }
+                    Ok(*elem_t)
+                } else {
+                    Err(ErrorKind::TriedIndexingNonArray(expr_t))
+                }
+            }
+            ExprKind::Array(expressions) => {
+                let mut expr_result = try_all(
+                    expressions
+                        .iter_mut()
+                        .map(|e| e.typecheck(state, hints, hint_t))
+                        .collect(),
+                );
+                match &mut expr_result {
+                    Ok(expr_types) => {
+                        let mut iter = expr_types.iter_mut();
+                        if let Some(first) = iter.next() {
+                            for other in iter {
+                                state.ok(first.collapse_into(other), self.1);
+                            }
+                            Ok(first.clone())
+                        } else {
+                            Ok(Array(Box::new(Void), 0))
+                        }
+                    }
+                    Err(errors) => {
+                        state.note_errors(errors, self.1);
+                        Ok(Array(Box::new(Vague(Unknown)), expressions.len() as u64))
+                    }
+                }
+            }
         }
     }
 }
diff --git a/reid/src/mir/typeinference.rs b/reid/src/mir/typeinference.rs
index 42ea667..8920d3b 100644
--- a/reid/src/mir/typeinference.rs
+++ b/reid/src/mir/typeinference.rs
@@ -6,7 +6,7 @@
 
 use std::{convert::Infallible, iter};
 
-use crate::util::try_all;
+use crate::{mir::TypeKind, util::try_all};
 
 use super::{
     pass::{Pass, PassState, ScopeVariable},
@@ -293,14 +293,19 @@ impl Expression {
                                 ))
                                 .unwrap())
                         } else {
-                            todo!();
+                            Ok(type_refs
+                                .from_type(&Array(Box::new(TypeKind::Void), 0))
+                                .unwrap())
                         }
                     }
                     Err(errors) => {
-                        for error in errors {
-                            state.ok::<_, Infallible>(Err(error.clone()), self.1);
-                        }
-                        todo!();
+                        state.note_errors(errors, self.1);
+                        Ok(type_refs
+                            .from_type(&TypeKind::Array(
+                                Box::new(TypeKind::Vague(Unknown)),
+                                expressions.len() as u64,
+                            ))
+                            .unwrap())
                     }
                 }
             }