Initial implementation of tuples in type checking

This leaves in place a bunch of TODOs and likely many bugs - notably, I haven't tested codegen/layout at all here.

crates/compiler/solve/tests/solve_expr.rs

@@ -1469,6 +1469,26 @@ mod solve_expr {
         infer_eq("{ x: 5, y : 3.14 }.x", "Num *");
     }
 
+    #[test]
+    fn record_literal_accessor_function() {
+        infer_eq(".x { x: 5, y : 3.14 }", "Num *");
+    }
+
+    #[test]
+    fn tuple_literal_accessor() {
+        infer_eq("(5, 3.14 ).0", "Num *");
+    }
+
+    #[test]
+    fn tuple_literal_accessor_function() {
+        infer_eq(".0 (5, 3.14 )", "Num *");
+    }
+
+    #[test]
+    fn tuple_literal_ty() {
+        infer_eq("(5, 3.14 )", "( Num *, Float * )*");
+    }
+
     #[test]
     fn record_arg() {
         infer_eq("\\rec -> rec.x", "{ x : a }* -> a");