From 188208b95935617985e56e8911559dc92a9fc71b Mon Sep 17 00:00:00 2001
From: David Nadlinger <code@klickverbot.at>
Date: Fri, 22 Apr 2022 22:46:24 +0100
Subject: [PATCH] core/typecheck: Implement unification for scalar indexing of
 ndarrays

---
 nac3core/src/typecheck/type_inferencer/test.rs |  5 +++--
 nac3core/src/typecheck/typedef/mod.rs          | 14 +++++++++-----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/nac3core/src/typecheck/type_inferencer/test.rs b/nac3core/src/typecheck/type_inferencer/test.rs
index 0ac4d99d..129043cb 100644
--- a/nac3core/src/typecheck/type_inferencer/test.rs
+++ b/nac3core/src/typecheck/type_inferencer/test.rs
@@ -518,12 +518,13 @@ impl TestEnvironment {
         a = array([1, 2])
         a0 = a[0]
         b = array([[1, 2], [3, 4]])
-        # b0 = b[0]
+        b0 = b[0]
         b00 = b[0, 0]
         c = 1
         ac = a[c]
     "},
-    [("a", "ndarray[int32, 1]"), ("b", "ndarray[int32, 2]"), ("a0", "int32"), ("b00", "int32"), ("ac", "int32")].iter().cloned().collect(),
+    [("a", "ndarray[int32, 1]"), ("a0", "int32"), ("b", "ndarray[int32, 2]"),
+     ("b0", "ndarray[int32, 1]"), ("b00", "int32"), ("ac", "int32")].iter().cloned().collect(),
     &[]
     ; "array test")]
 #[test_case(indoc! {"
diff --git a/nac3core/src/typecheck/typedef/mod.rs b/nac3core/src/typecheck/typedef/mod.rs
index 95c16562..0935946f 100644
--- a/nac3core/src/typecheck/typedef/mod.rs
+++ b/nac3core/src/typecheck/typedef/mod.rs
@@ -662,13 +662,17 @@ impl Unifier {
                 for (k, v) in fields.iter() {
                     match *k {
                         RecordKey::Int(_) => {
-                            if *num_dims > 1 {
-                                unreachable!("xxx implement unification for scalar indexing of multidimensional array");
-                            }
-                            self.unify_impl(v.ty, *ty, false).map_err(|e| e.at(v.loc))?
+                            // .<n> is generated during generic scalar indexing lowering.
+                            let indexed_ty = if *num_dims == 1 {
+                                *ty
+                            } else {
+                                self.add_ty(TNDArray { ty: *ty, num_dims: *num_dims - 1 })
+                            };
+                            self.unify_impl(v.ty, indexed_ty, false).map_err(|e| e.at(v.loc))?
                         }
                         RecordKey::Str(_) => {
-                            return Err(TypeError::new(TypeErrorKind::NoSuchField(*k, b), v.loc))
+                            // xxx: Implement .shape here?
+                            return Err(TypeError::new(TypeErrorKind::NoSuchField(*k, b), v.loc));
                         }
                     }
                 }