Fix defclass construction

Python Class AST expects a body which is a list of ast.Expr. Force
every entry to be stored as a statement. This means we'll preserve
print statements.

Python also doesn't construct docstrings in classes by setting a
__doc__ attribute, it does it by inspecting the first ast.Expr node of
the class. But this means we can remove the special handler for it.

NEWS.rst

@@ -27,6 +27,7 @@ Bug Fixes
 ------------------------------
 * Fix `(return)` so it works correctly to exit a Python 2 generator
 * Fixed a case where `->` and `->>` duplicated an argument
+* Fixed bugs that caused `defclass` to drop statements or crash
 
 Misc. Improvements
 ----------------------------

hy/compiler.py

@@ -2072,12 +2072,7 @@ class HyASTCompiler(object):
 
         # grab the doc string, if there is one
         if expressions and isinstance(expressions[0], HyString):
-            docstring = expressions.pop(0)
+            body += self.compile(expressions.pop(0)).expr_as_stmt()
-            symb = HySymbol("__doc__")
-            symb.start_line = docstring.start_line
-            symb.start_column = docstring.start_column
-            body += self._compile_assign(symb, docstring)
-            body += body.expr_as_stmt()
 
         if expressions and isinstance(expressions[0], HyList) \
            and not isinstance(expressions[0], HyExpression):
@@ -2088,7 +2083,8 @@ class HyASTCompiler(object):
             body += self.compile(rewire_init(expr))
 
         for expression in expressions:
-            body += self.compile(rewire_init(macroexpand(expression, self)))
+            e = self.compile(rewire_init(macroexpand(expression, self)))
+            body += e + e.expr_as_stmt()
 
         if not body.stmts:
             body += asty.Pass(expressions)

tests/native_tests/defclass.hy

@@ -127,3 +127,14 @@
   (setv b (B))
   (assert (= a.x 1))
   (assert (= b.x 2)))
+
+(defn test-class-sideeffects []
+  "NATIVE: test that defclass runs all expressions"
+  (defn set-sentinel []
+    (setv set-sentinel.set True))
+  (setv set-sentinel.set False)
+
+  (defclass A []
+    (set-sentinel))
+
+  (assert set-sentinel.set))