Fix leakage of exc_info from eval to exec call.

`exec()` was always executed in the `except SyntaxError` block of the try
around `eval()`, and because of this ``sys.exc_info()`` would not see the right
exception if called as a statement.

See: prompt-toolkit#435

Thanks to Peter Holloway for the proposed fix.

Author: jonathanslenders

ptpython/repl.py

@@ -199,9 +199,7 @@ def eval(self, line: str) -> object:
             try:
                 code = self._compile_with_flags(line, "eval")
             except SyntaxError:
-                # If not a valid `eval` expression, run using `exec` instead.
-                code = self._compile_with_flags(line, "exec")
-                exec(code, self.get_globals(), self.get_locals())
+                pass
             else:
                 # No syntax errors for eval. Do eval.
                 result = eval(code, self.get_globals(), self.get_locals())
@@ -212,6 +210,13 @@ def eval(self, line: str) -> object:
                 self._store_eval_result(result)
                 return result
 
+            # If not a valid `eval` expression, run using `exec` instead.
+            # Note that we shouldn't run this in the `except SyntaxError` block
+            # above, then `sys.exc_info()` would not report the right error.
+            # See issue: https://github.com/prompt-toolkit/ptpython/issues/435
+            code = self._compile_with_flags(line, "exec")
+            exec(code, self.get_globals(), self.get_locals())
+
         return None
 
     async def eval_async(self, line: str) -> object:
@@ -231,9 +236,7 @@ async def eval_async(self, line: str) -> object:
             try:
                 code = self._compile_with_flags(line, "eval")
             except SyntaxError:
-                # If not a valid `eval` expression, run using `exec` instead.
-                code = self._compile_with_flags(line, "exec")
-                exec(code, self.get_globals(), self.get_locals())
+                pass
             else:
                 # No syntax errors for eval. Do eval.
                 result = eval(code, self.get_globals(), self.get_locals())
@@ -244,6 +247,10 @@ async def eval_async(self, line: str) -> object:
                 self._store_eval_result(result)
                 return result
 
+            # If not a valid `eval` expression, run using `exec` instead.
+            code = self._compile_with_flags(line, "exec")
+            exec(code, self.get_globals(), self.get_locals())
+
         return None
 
     def _store_eval_result(self, result: object) -> None: