Issue #17 Fix failure to issue #line directive for first include …

…file in a file. Thanks to Sei-Lisa for reporting this.

README.rst

@@ -405,6 +405,8 @@ v1.20 (7th January 2019):
   PLY no longer works using pypi packaging, David wants people to include the source of
   PLY directly. pcpp does this via a git submodule, and has setuptools bundle the submodule.
 - Add a formal LICENSE.txt file, as requested by Sei-Lisa.
+- Fix failure to issue ``#line`` directive for first include file in a file. Thanks to
+  Sei-Lisa for reporting this.
 
 v1.1 (19th June 2018):
 ----------------------

pcpp/preprocessor.py

@@ -1521,6 +1521,8 @@ def write(self, oh=sys.stdout):
             emitlinedirective = (blanklines > 6) and self.line_directive is not None
             if hasattr(toks[0], 'source'):
                 if lastsource is None:
+                    if toks[0].source is not None:
+                        emitlinedirective = True
                     lastsource = toks[0].source
                 elif lastsource != toks[0].source:
                     emitlinedirective = True

tests/issue0017-ref.i

@@ -1,4 +1,3 @@
-#line 1 "tests/issue0017/issue0017.c"
 #line 1 "inc.h"
 inc1
 

tests/issue0017.py

@@ -0,0 +1,23 @@
+from __future__ import absolute_import, print_function
+import unittest
+
+class issue0017(unittest.TestCase):
+    def runTest(self):
+        from pcpp import Preprocessor
+        import os, sys
+
+        p = Preprocessor()
+        path = 'tests/issue0017/issue0017.c'
+        with open(path, 'rt') as ih:
+            p.parse(ih.read(), path)
+        with open('tests/issue0017.i', 'w') as oh:
+            p.write(oh)
+        with open('tests/issue0017.i', 'r') as ih:
+            was = ih.read()
+        with open('tests/issue0017-ref.i', 'r') as ih:
+            shouldbe = ih.read()
+        if was != shouldbe:
+            print("Should be:\n" + shouldbe, file = sys.stderr)
+            print("\n\nWas:\n" + was, file = sys.stderr)
+        self.assertEqual(p.return_code, 0)
+        self.assertEqual(was, shouldbe)