fstrings: fix more bugs

Not sure about the refcounting

Cython/Compiler/ExprNodes.py

@@ -2907,8 +2907,8 @@ class JoinedStrNode(ExprNode):
             code.put_giveref(value.py_result())
             code.putln('PyList_SET_ITEM(%s, %s, %s);' % (list_var, i, value.py_result()))
         code.putln('%s = PyUnicode_Join(%s, %s); __Pyx_DECREF(%s); %s' % (
-            self.result(), 
-            Naming.empty_unicode, 
+            self.result(),
+            Naming.empty_unicode,
             list_var,
             list_var,
             code.error_goto_if_null(list_var, self.pos)))
@@ -2937,8 +2937,8 @@ class FormattedValueNode(ExprNode):
 
     def generate_result_code(self, code):
         value_result = self.value.py_result()
+        conversion_result = Naming.quick_temp_cname
         format_spec_result = self.format_spec.py_result()
-        # TODO conversion chars
         if self.conversion_char == 's':
             fn = 'PyObject_Str'
         elif self.conversion_char == 'r':
@@ -2948,25 +2948,31 @@ class FormattedValueNode(ExprNode):
         else:
             fn = None
 
+        code.putln('{')
+
         if fn is not None:
-            code.putln('%s = %s(%s); %s' % (
-                value_result,
+            code.putln('PyObject *%s = %s(%s); %s' % (
+                conversion_result,
                 fn,
                 value_result,
-                code.error_goto_if_null(value_result, self.pos)
+                code.error_goto_if_null(conversion_result, self.pos)
             ))
-            code.put_gotref(value_result)
-            decref_line = '__Pyx_DECREF(%s);' % value_result
         else:
-            decref_line = ''
+            code.putln('PyObject *%s = %s;' % (conversion_result, value_result))
+            #code.put_incref(conversion_result, py_object_type)
+        # TODO this should need more refcounting, figure out whether this is correct
+        #code.put_gotref(conversion_result)
+        #code.put_decref(value_result, self.value.ctype())
+        decref_line = '' # '__Pyx_DECREF(%s);' % conversion_result
 
         code.putln("%s = PyObject_Format(%s, %s); %s %s" % (
             self.result(),
-            value_result,
+            conversion_result,
             format_spec_result,
             decref_line,
             code.error_goto_if_null(self.result(), self.pos)))
         code.put_gotref(self.py_result())
+        code.putln('}')
 
 
 #-------------------------------------------------------------------

Cython/Compiler/Parsing.py

@@ -998,15 +998,14 @@ def p_f_string(s, unicode_value, pos):
     current_literal_start = 0
     while i < size:
         c = unicode_value[i]
-        if c == '}':
-            if i + 1 >= size or unicode_value[i + 1] != '}':
-                s.error("single '}' encountered in format string")
-            else:
-                i += 2
-        elif c == '{':
-            # double { escapes it
-            if i + 1 < size and unicode_value[i + 1] == '{':
+        if c in ('{', '}'):
+            if i + 1 < size and unicode_value[i + 1] == c:
+                encoded_str = EncodedString(unicode_value[current_literal_start:i + 1])
+                values.append(ExprNodes.UnicodeNode(pos, value = encoded_str))
                 i += 2
+                current_literal_start = i
+            elif c == '}':
+                s.error("single '}' encountered in format string")
             else:
                 encoded_str = EncodedString(unicode_value[current_literal_start:i])
                 values.append(ExprNodes.UnicodeNode(pos, value = encoded_str))
@@ -1018,7 +1017,6 @@ def p_f_string(s, unicode_value, pos):
 
     encoded_str = EncodedString(unicode_value[current_literal_start:])
     values.append(ExprNodes.UnicodeNode(pos, value = encoded_str))
-    print("F-STRING VALUES", values)
     return values
 
 
@@ -1109,8 +1107,6 @@ def p_f_string_expr(s, unicode_value, pos, starting_index):
     if terminal_char != '}':
         s.error("missing '}' in format string expression'")
 
-    print('expr=%r, conversion_char=%r, format_spec=%r' % (expr_str, conversion_char, format_spec_str))
-
     # parse the expression
     name = 'format string expression'
     code_source = StringSourceDescriptor(name, expr_str)