WIP: core/typecheck: after np.newaxis and ...

nac3core/src/codegen/structure/ndarray/indexing.rs

@@ -335,6 +335,8 @@ pub mod util {
 
                     RustNDIndex::Slice(RustUserSlice { start, stop, step })
                 } else {
+                    todo!("implement me");
+
                     // Anything else that is not a slice (might be illegal values),
                     // For nac3core, this should be e.g., an int32 constant, an int32 variable, otherwise its an error
                     let index = generator.gen_expr(ctx, index_expr)?.unwrap().to_basic_value_enum(

nac3core/src/toplevel/mod.rs

@@ -31,6 +31,7 @@ pub mod builtins;
 pub mod composer;
 pub mod helper;
 pub mod numpy;
+pub mod option;
 pub mod type_annotation;
 use composer::*;
 use type_annotation::*;

nac3core/src/toplevel/numpy.rs

@@ -1,5 +1,3 @@
-use std::sync::Arc;
-
 use crate::{
     symbol_resolver::SymbolValue,
     toplevel::helper::PrimDef,

nac3core/src/toplevel/option.rs

@@ -0,0 +1,46 @@
+use itertools::Itertools;
+
+use crate::{
+    toplevel::helper::PrimDef,
+    typecheck::{
+        type_inferencer::PrimitiveStore,
+        typedef::{Type, TypeEnum, Unifier, VarMap},
+    },
+};
+
+// TODO: This entire module is duplicated code (numpy.rs also has these kinds of things)
+
+/// Creates a `option` [`Type`] with the given type arguments.
+///
+/// * `dtype` - The element type of the `option`, or [`None`] if the type variable is not
+/// specialized.
+/// * `ndims` - The number of dimensions of the `option`, or [`None`] if the type variable is not
+/// specialized.
+pub fn make_option_ty(
+    unifier: &mut Unifier,
+    primitives: &PrimitiveStore,
+    dtype: Option<Type>,
+) -> Type {
+    subst_option_tvars(unifier, primitives.option, dtype)
+}
+
+/// Substitutes type variables in `option`.
+///
+/// * `dtype` - The element type of the `option`, or [`None`] if the type variable is not
+/// specialized.
+pub fn subst_option_tvars(unifier: &mut Unifier, option: Type, dtype: Option<Type>) -> Type {
+    let TypeEnum::TObj { obj_id, params, .. } = &*unifier.get_ty_immutable(option) else {
+        panic!("Expected `option` to be TObj, but got {}", unifier.stringify(option))
+    };
+    debug_assert_eq!(*obj_id, PrimDef::Option.id());
+
+    let tvar_ids = params.iter().map(|(obj_id, _)| *obj_id).collect_vec();
+    debug_assert_eq!(tvar_ids.len(), 1);
+
+    let mut tvar_subst = VarMap::new();
+    if let Some(dtype) = dtype {
+        tvar_subst.insert(tvar_ids[0], dtype);
+    }
+
+    unifier.subst(option, &tvar_subst).unwrap_or(option)
+}

nac3core/src/typecheck/function_check.rs

@@ -80,7 +80,7 @@ impl<'a> Inferencer<'a> {
                 return Err(HashSet::from([format!(
                     "expected concrete type at {} but got {}",
                     expr.location,
-                    self.unifier.get_ty(*ty).get_type_name()
+                    self.unifier.stringify(*ty)
                 )]));
             }
         }

nac3core/src/typecheck/type_inferencer/mod.rs

@@ -11,6 +11,7 @@ use super::{
         RecordField, RecordKey, Type, TypeEnum, TypeVar, Unifier, VarMap,
     },
 };
+use crate::toplevel::option::make_option_ty;
 use crate::{
     symbol_resolver::{SymbolResolver, SymbolValue},
     toplevel::{
@@ -2264,16 +2265,30 @@ impl<'a> Inferencer<'a> {
                     }
                 }
                 ExprKind::Constant { value: Constant::Ellipsis, .. } => {
-                    // Handle `...`. Do nothing.
+                    // Handle `...`.
+
+                    // See https://git.m-labs.hk/M-Labs/nac3/issues/486
+                    // Force `...` to have `()` (completely bogus) to make it concrete.
+                    let empty_tuple = TypeEnum::TTuple { ty: vec![], is_vararg_ctx: false };
+                    let empty_tuple = self.unifier.add_ty(empty_tuple);
+                    self.unify(index.custom.unwrap(), empty_tuple, &index.location)?;
                 }
                 ExprKind::Name { id, .. } if id == &"none".into() => {
                     // Handle `np.newaxis` / `None`.
                     dims_to_subtract -= 1;
+
+                    // "none" itself has type `Option[T]`, and since we have a stray `T` (non-concrete type).
+                    // We will force the type to be `Option[()]` to make it concrete. (TODO: is there a void type?)
+                    let empty_tuple = TypeEnum::TTuple { ty: vec![], is_vararg_ctx: false };
+                    let empty_tuple = self.unifier.add_ty(empty_tuple);
+                    let expected_type =
+                        make_option_ty(self.unifier, self.primitives, Some(empty_tuple));
+                    self.unify(index.custom.unwrap(), expected_type, &index.location)?;
                 }
                 _ => {
                     // Treat anything else as an integer index, and force unify their type to int32.
-                    self.unify(index.custom.unwrap(), self.primitives.int32, &index.location)?;
                     dims_to_subtract += 1;
+                    self.unify(index.custom.unwrap(), self.primitives.int32, &index.location)?;
                 }
             }
         }

nac3core/src/typecheck/typedef/mod.rs

@@ -621,8 +621,7 @@ impl Unifier {
     }
 
     pub fn unify_call(
-        &mut self,
-        call: &Call,
+        &mut self, call: &Call,
         b: Type,
         signature: &FunSignature,
     ) -> Result<(), TypeError> {