[Python-checkins] bpo-32028: Fix suggestions for indented print statements (GH-4688)

[Nick Coghlan]

https://github.com/python/cpython/commit/d57f26c753dce61f72b52b96db3a3253d9f2fc3e
commit: d57f26c753dce61f72b52b96db3a3253d9f2fc3e
branch: master
author: Sanyam Khurana <8039608+CuriousLearner at users.noreply.github.com>
committer: Nick Coghlan <ncoghlan at gmail.com>
date: 2018-01-20T13:12:22+10:00
summary:

bpo-32028: Fix suggestions for indented print statements (GH-4688)

The suggested replacement for print statements previously failed to account
for leading whitespace and hence could end up including unwanted text in
the proposed call to the print builtin.

Patch by Sanyam Khurana.

files:
A Misc/NEWS.d/next/Core and Builtins/2017-12-03-22-29-13.bpo-32028.KC2w4Q.rst
M Lib/test/test_print.py
M Objects/exceptions.c

diff --git a/Lib/test/test_print.py b/Lib/test/test_print.py
index e6434feaf5e..7bc23cf9fc6 100644
--- a/Lib/test/test_print.py
+++ b/Lib/test/test_print.py
@@ -156,6 +156,15 @@ def test_string_with_excessive_whitespace(self):
 
         self.assertIn('print("Hello World", end=" ")', str(context.exception))
 
+    def test_string_with_leading_whitespace(self):
+        python2_print_str = '''if 1:
+            print "Hello World"
+        '''
+        with self.assertRaises(SyntaxError) as context:
+            exec(python2_print_str)
+
+        self.assertIn('print("Hello World")', str(context.exception))
+
     def test_stream_redirection_hint_for_py2_migration(self):
         # Test correct hint produced for Py2 redirection syntax
         with self.assertRaises(TypeError) as context:
diff --git a/Misc/NEWS.d/next/Core and Builtins/2017-12-03-22-29-13.bpo-32028.KC2w4Q.rst b/Misc/NEWS.d/next/Core and Builtins/2017-12-03-22-29-13.bpo-32028.KC2w4Q.rst
new file mode 100644
index 00000000000..8e2b2e1b350
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2017-12-03-22-29-13.bpo-32028.KC2w4Q.rst	
@@ -0,0 +1,3 @@
+Leading whitespace is now correctly ignored when generating suggestions
+for converting Py2 print statements to Py3 builtin print function calls.
+Patch by Sanyam Khurana.
diff --git a/Objects/exceptions.c b/Objects/exceptions.c
index 4901eb1cc3c..d59abd1a7f4 100644
--- a/Objects/exceptions.c
+++ b/Objects/exceptions.c
@@ -2846,17 +2846,23 @@ _set_legacy_print_statement_msg(PySyntaxErrorObject *self, Py_ssize_t start)
 
     // PRINT_OFFSET is to remove `print ` word from the data.
     const int PRINT_OFFSET = 6;
-    Py_ssize_t text_len = PyUnicode_GET_LENGTH(self->text);
-    PyObject *data = PyUnicode_Substring(self->text, PRINT_OFFSET, text_len);
-
+    const int STRIP_BOTH = 2;
+    // Issue 32028: Handle case when whitespace is used with print call
+    PyObject *initial_data = _PyUnicode_XStrip(self->text, STRIP_BOTH, strip_sep_obj);
+    if (initial_data == NULL) {
+        Py_DECREF(strip_sep_obj);
+        return -1;
+    }
+    Py_ssize_t text_len = PyUnicode_GET_LENGTH(initial_data);
+    PyObject *data = PyUnicode_Substring(initial_data, PRINT_OFFSET, text_len);
+    Py_DECREF(initial_data);
     if (data == NULL) {
         Py_DECREF(strip_sep_obj);
         return -1;
     }
-    PyObject *new_data = _PyUnicode_XStrip(data, 2, strip_sep_obj);
+    PyObject *new_data = _PyUnicode_XStrip(data, STRIP_BOTH, strip_sep_obj);
     Py_DECREF(data);
     Py_DECREF(strip_sep_obj);
-
     if (new_data == NULL) {
         return -1;
     }