Merge pull request #1400 from Kodiologist/nullary-break-continue

Forbid arguments to `break` and `continue`

NEWS

@@ -34,6 +34,8 @@ Changes from 0.13.0
    * Fixed a crash when `with` suppresses an exception. `with` now returns
      `None` in this case.
    * `assoc` now evaluates its arguments only once each
+   * `break` and `continue` now raise an error when given arguments
+     instead of silently ignoring them
 
    [ Misc. Improvements ]
    * `read`, `read_str`, and `eval` are exposed and documented as top-level

hy/compiler.py

@@ -1123,6 +1123,7 @@ class HyASTCompiler(object):
         return ret
 
     @builds("break")
+    @checkargs(0)
     def compile_break_expression(self, expr):
         ret = ast.Break(lineno=expr.start_line,
                         col_offset=expr.start_column)
@@ -1130,6 +1131,7 @@ class HyASTCompiler(object):
         return ret
 
     @builds("continue")
+    @checkargs(0)
     def compile_continue_expression(self, expr):
         ret = ast.Continue(lineno=expr.start_line,
                            col_offset=expr.start_column)

tests/compilers/test_ast.py

@@ -336,6 +336,13 @@ def test_ast_invalid_for():
     cant_compile("(for* [a 1] (else 1 2))")
 
 
+def test_nullary_break_continue():
+    can_compile("(while 1 (break))")
+    cant_compile("(while 1 (break 1))")
+    can_compile("(while 1 (continue))")
+    cant_compile("(while 1 (continue 1))")
+
+
 def test_ast_expression_basics():
     """ Ensure basic AST expression conversion works. """
     code = can_compile("(foo bar)").body[0]