Fix crash when file starts with a semicolon (#310)

2 files changed, 24 insertions, 3 deletions

diff --git a/pycparser/c_parser.py b/pycparser/c_parser.py
index 0e6e755..4e1889d 100644
--- a/pycparser/c_parser.py
+++ b/pycparser/c_parser.py
@@ -529,8 +529,7 @@ class CParser(PLYParser):
     def p_translation_unit_2(self, p):
         """ translation_unit    : translation_unit external_declaration
         """
-        if p[2] is not None:
-            p[1].extend(p[2])
+        p[1].extend(p[2])
         p[0] = p[1]
 
     # Declarations always come as lists (because they can be
@@ -557,7 +556,7 @@ class CParser(PLYParser):
     def p_external_declaration_4(self, p):
         """ external_declaration    : SEMI
         """
-        p[0] = None
+        p[0] = []
 
     def p_pp_directive(self, p):
         """ pp_directive  : PPHASH
diff --git a/tests/test_c_parser.py b/tests/test_c_parser.py
index 34c1f1e..c09e04d 100755
--- a/tests/test_c_parser.py
+++ b/tests/test_c_parser.py
@@ -136,6 +136,15 @@ class TestCParser_fundamentals(TestCParser_base):
             ['Decl', 'foo',
                 ['TypeDecl', ['IdentifierType', ['int']]]])
 
+    def test_initial_semi(self):
+        t = self.parse(';')
+        self.assertEqual(len(t.ext), 0)
+        t = self.parse(';int foo;')
+        self.assertEqual(len(t.ext), 1)
+        self.assertEqual(expand_decl(t.ext[0]),
+            ['Decl', 'foo',
+                ['TypeDecl', ['IdentifierType', ['int']]]])
+
     def test_coords(self):
         """ Tests the "coordinates" of parsed elements - file
             name, line and column numbers, with modification
@@ -828,6 +837,19 @@ class TestCParser_fundamentals(TestCParser_base):
                     ['Decl', 'd',
                         ['TypeDecl', ['IdentifierType', ['char']]]]]]]])
 
+    def test_struct_with_initial_semi(self):
+        s1 = """
+            struct {
+                ;int a;
+            } foo;
+        """
+        s1_ast = self.parse(s1)
+        self.assertEqual(expand_decl(s1_ast.ext[0]),
+            ['Decl', 'foo',
+                ['TypeDecl', ['Struct', None,
+                    [['Decl', 'a',
+                        ['TypeDecl', ['IdentifierType', ['int']]]]]]]])
+
     def test_anonymous_struct_union(self):
         s1 = """
             union