add more tests

zokrates_cli/examples/compile_errors/assembly/unallowed_type_in_assignment.zok

@@ -0,0 +1,6 @@
+def main(bool a) {
+    bool mut b = false;
+    asm {
+        b <-- a;
+    }
+}

zokrates_cli/examples/compile_errors/assembly/unallowed_type_in_constrained_assignment.zok

@@ -0,0 +1,6 @@
+def main() {
+    field[2] mut a = [0; 2];
+    asm {
+        a <== [1, 2];
+    }
+}

zokrates_core/src/semantics.rs

@@ -1834,7 +1834,7 @@ impl<'ast, T: Field> Checker<'ast, T> {
                         }
                         ty => Err(ErrorInner {
                             span: Some(span),
-                            message: format!("Assignee must be a field element, found {}", ty),
+                            message: format!("Assignee must be of type field, found {}", ty),
                         }),
                     },
                     false => {
@@ -1849,7 +1849,7 @@ impl<'ast, T: Field> Checker<'ast, T> {
                             },
                             false => Err(ErrorInner {
                                 span: Some(span),
-                                message: "Assignee must be a field element or a composite type of field elements".to_string(),
+                                message: "Assignee must be of type field or a composite type of field elements".to_string(),
                             })
                         }
                     }

zokrates_core_test/tests/tests/assembly/composite_assignment.json

@@ -0,0 +1,16 @@
+{
+  "curves": ["Bn128"],
+  "max_constraint_count": 1,
+  "tests": [
+    {
+      "input": {
+        "values": ["2", "2", "4"]
+      },
+      "output": {
+        "Ok": {
+          "value": []
+        }
+      }
+    }
+  ]
+}

zokrates_core_test/tests/tests/assembly/composite_assignment.zok

@@ -0,0 +1,7 @@
+def main(field a, field b, field c) {
+    field[2] mut out = [0; 2];
+    asm {
+        out <-- [a, b];
+        out[0] * out[1] === c;
+    }
+}