allow useless trailing semicolons in some places where people tend to put...

allow useless trailing semicolons in some places where people tend to put them, but warn about them (trac ticket 832)

Cython/Compiler/Parsing.py

@@ -1226,7 +1226,7 @@ def p_pass_statement(s, with_newline = 0):
     pos = s.position()
     s.expect('pass')
     if with_newline:
-        s.expect_newline("Expected a newline")
+        s.expect_newline("Expected a newline", ignore_semicolon=True)
     return Nodes.PassStatNode(pos)
 
 def p_break_statement(s):
@@ -1793,7 +1793,7 @@ def p_DEF_statement(s):
     value = expr.compile_time_value(denv)
     #print "p_DEF_statement: %s = %r" % (name, value) ###
     denv.declare(name, value)
-    s.expect_newline()
+    s.expect_newline("Expected a newline", ignore_semicolon=True)
     return Nodes.PassStatNode(pos)
 
 def p_IF_statement(s, ctx):
@@ -1950,7 +1950,7 @@ def p_suite_with_docstring(s, ctx, with_doc_only=False):
             body = p_simple_statement_list(s, ctx)
         else:
             body = p_pass_statement(s)
-            s.expect_newline("Syntax error in declarations")
+            s.expect_newline("Syntax error in declarations", ignore_semicolon=True)
     if not with_doc_only:
         doc, body = _extract_docstring(body)
     return doc, body
@@ -2842,7 +2842,7 @@ def p_c_func_or_var_declaration(s, pos, ctx):
                                         assignable = 1, nonempty = 1)
             declarators.append(declarator)
         doc_line = s.start_line + 1
-        s.expect_newline("Syntax error in C variable declaration")
+        s.expect_newline("Syntax error in C variable declaration", ignore_semicolon=True)
         if ctx.level in ('c_class', 'c_class_pxd') and s.start_line == doc_line:
             doc = p_doc_string(s)
         else:
@@ -2876,7 +2876,7 @@ def p_ctypedef_statement(s, ctx):
     else:
         base_type = p_c_base_type(s, nonempty = 1)
         declarator = p_c_declarator(s, ctx, is_type = 1, nonempty = 1)
-        s.expect_newline("Syntax error in ctypedef statement")
+        s.expect_newline("Syntax error in ctypedef statement", ignore_semicolon=True)
         return Nodes.CTypeDefNode(
             pos, base_type = base_type,
             declarator = declarator,
@@ -3090,8 +3090,7 @@ def p_ignorable_statement(s):
     if s.sy == 'BEGIN_STRING':
         pos = s.position()
         string_node = p_atom(s)
-        if s.sy != 'EOF':
-            s.expect_newline("Syntax error in string")
+        s.expect_newline("Syntax error in string", ignore_semicolon=True)
         return Nodes.ExprStatNode(pos, expr=string_node)
     return None
 
@@ -3100,8 +3099,7 @@ def p_doc_string(s):
     if s.sy == 'BEGIN_STRING':
         pos = s.position()
         kind, bytes_result, unicode_result = p_cat_string_literal(s)
-        if s.sy != 'EOF':
-            s.expect_newline("Syntax error in doc string")
+        s.expect_newline("Syntax error in doc string", ignore_semicolon=True)
         if kind in ('u', ''):
             return unicode_result
         warning(pos, "Python 3 requires docstrings to be unicode strings")

Cython/Compiler/Scanning.pxd

@@ -51,4 +51,4 @@ cdef class PyrexScanner(Scanner):
     cdef expected(self, what, message = *)
     cdef expect_indent(self)
     cdef expect_dedent(self)
-    cdef expect_newline(self, message = *)
+    cdef expect_newline(self, message=*, bint ignore_semicolon=*)

Cython/Compiler/Scanning.py

@@ -10,12 +10,12 @@ import platform
 
 import cython
 cython.declare(EncodedString=object, any_string_prefix=unicode, IDENT=unicode,
-               print_function=object)
+               print_function=object, error=object, warning=object)
 
 from .. import Utils
 from ..Plex.Scanners import Scanner
 from ..Plex.Errors import UnrecognizedInput
-from .Errors import error
+from .Errors import error, warning
 from .Lexicon import any_string_prefix, make_lexicon, IDENT
 from .Future import print_function
 
@@ -479,7 +479,13 @@ class PyrexScanner(Scanner):
         self.expect('DEDENT',
             "Expected a decrease in indentation level")
 
-    def expect_newline(self, message = "Expected a newline"):
+    def expect_newline(self, message="Expected a newline", ignore_semicolon=False):
         # Expect either a newline or end of file
+        useless_trailing_semicolon = None
+        if ignore_semicolon and self.sy == ';':
+            useless_trailing_semicolon = self.position()
+            self.next()
         if self.sy != 'EOF':
             self.expect('NEWLINE', message)
+        if useless_trailing_semicolon is not None:
+            warning(useless_trailing_semicolon, "useless trailing semicolon")

tests/compile/cdef_syntax.pyx

+# mode: compile
+
+# the following are valid syntax constructs and should not produce errors
+
+ctypedef int x;
+
+cdef no_semi():
+    cdef int i
+
+cdef with_semi():
+    cdef int i;

tests/errors/syntax_warnings.pyx

+# mode: error
+# tag: werror
+
+cdef useless_semicolon():
+    cdef int i;
+    pass;
+
+ctypedef int x;
+
+
+_ERRORS="""
+5:14: useless trailing semicolon
+6:8: useless trailing semicolon
+8:14: useless trailing semicolon
+"""