Add - (minus) operator for arrays (#1376)

Author: Akuli

compiler/ast_to_builder.jou

@@ -280,6 +280,13 @@ class AstToBuilder:
         return self.builder.dereference(out_ptr)
 
     def build_binop(self, op: AstExpressionKind, lhs: BuilderValue, rhs: BuilderValue) -> BuilderValue:
+        if (
+            (op == AstExpressionKind.Add or op == AstExpressionKind.Sub)
+            and lhs.type == rhs.type
+            and lhs.type.kind == TypeKind.Array
+        ):
+            return self.build_array_binop(op, lhs, rhs)
+
         match op:
             case AstExpressionKind.Eq:
                 return self.builder.eq(lhs, rhs)
@@ -294,13 +301,8 @@ class AstToBuilder:
             case AstExpressionKind.Ge:
                 return self.builder.not_(self.builder.lt(lhs, rhs))
             case AstExpressionKind.Add:
-                assert lhs.type == rhs.type
-                match lhs.type.kind:
-                    case TypeKind.Array:
-                        return self.build_array_binop(op, lhs, rhs)
-                    case _:
-                        # TODO: this should probably be split up to separate int vs floating adds
-                        return self.builder.add(lhs, rhs)
+                # TODO: These should probably be split up to separate e.g. int vs floating adds.
+                return self.builder.add(lhs, rhs)
             case AstExpressionKind.Sub:
                 return self.builder.sub(lhs, rhs)
             case AstExpressionKind.Mul:

compiler/typecheck/step3_function_and_method_bodies.jou

@@ -500,7 +500,7 @@ def check_binop(
         or (got_enums and not equals_compare)
         or (got_pointers and not some_kind_of_compare)
         or (need_integers and not got_integers)
-        or (got_number_arrays and op != AstExpressionKind.Add)
+        or (got_number_arrays and op != AstExpressionKind.Add and op != AstExpressionKind.Sub)
     ):
         snprintf(msg, sizeof(msg), "wrong types: cannot %s %s and %s", do_what, ltype.name, rtype.name)
         fail(location, msg)

tests/should_succeed/array_add.jou

@@ -0,0 +1,40 @@
+import "stdlib/io.jou"
+
+def test_add() -> None:
+    array = [1, 2] + [3, 4]
+    printf("%d %d\n", array[0], array[1])  # Output: 4 6
+
+    array += [1, 1]
+    printf("%d %d\n", array[0], array[1])  # Output: 5 7
+
+    with_offset = array + [0.5, 0.5]
+    printf("%f %f\n", with_offset[0], with_offset[1])  # Output: 5.500000 7.500000
+
+    with_float_offset = array + [0.5 as float, 0.5 as float]
+    printf("%f %f\n", with_float_offset[0], with_float_offset[1])  # Output: 5.500000 7.500000
+
+    # Output: Sizes: 16 and 8
+    printf("Sizes: %d and %d\n", sizeof(with_offset), sizeof(with_float_offset))
+
+
+def test_sub() -> None:
+    array = [1, 2] - [3, 5]
+    printf("%d %d\n", array[0], array[1])  # Output: -2 -3
+
+    array -= [1, 1]
+    printf("%d %d\n", array[0], array[1])  # Output: -3 -4
+
+    with_offset = array - [0.5, 0.5]
+    printf("%f %f\n", with_offset[0], with_offset[1])  # Output: -3.500000 -4.500000
+
+    with_float_offset = array - [0.5 as float, 0.5 as float]
+    printf("%f %f\n", with_float_offset[0], with_float_offset[1])  # Output: -3.500000 -4.500000
+
+    # Output: Sizes: 16 and 8
+    printf("Sizes: %d and %d\n", sizeof(with_offset), sizeof(with_float_offset))
+
+
+def main() -> int:
+    test_add()
+    test_sub()
+    return 0