gh-98931: Improve error message when the user types 'import x from y' instead of 'from y import x' (#98932)

Doc/whatsnew/3.12.rst

@@ -70,6 +70,18 @@ Important deprecations, removals or restrictions:
 
 * :pep:`623`, Remove wstr from Unicode
 
+Improved Error Messages
+=======================
+
+* Improve the :exc:`SyntaxError` error message when the user types ``import x
+  from y`` instead of ``from y import x``. Contributed by Pablo Galindo in :gh:`98931`.
+
+    >>> import a.y.z from b.y.z
+    Traceback (most recent call last):
+      File "<stdin>", line 1
+        import a.y.z from b.y.z
+        ^^^^^^^^^^^^^^^^^^^^^^^
+    SyntaxError: Did you mean to use 'from ... import ...' instead?
 
 New Features
 ============

Grammar/python.gram

@@ -194,7 +194,10 @@ yield_stmt[stmt_ty]: y=yield_expr { _PyAST_Expr(y, EXTRA) }
 
 assert_stmt[stmt_ty]: 'assert' a=expression b=[',' z=expression { z }] { _PyAST_Assert(a, b, EXTRA) }
 
-import_stmt[stmt_ty]: import_name | import_from
+import_stmt[stmt_ty]: 
+    | invalid_import
+    | import_name
+    | import_from
 
 # Import statements
 # -----------------
@@ -1230,6 +1233,10 @@ invalid_group:
         RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "cannot use starred expression here") }
     | '(' a='**' expression ')' {
         RAISE_SYNTAX_ERROR_KNOWN_LOCATION(a, "cannot use double starred expression here") }
+invalid_import:
+    | a='import' dotted_name 'from' dotted_name {
+        RAISE_SYNTAX_ERROR_STARTING_FROM(a, "Did you mean to use 'from ... import ...' instead?") }
+ 
 invalid_import_from_targets:
     | import_from_as_names ',' NEWLINE {
         RAISE_SYNTAX_ERROR("trailing comma not allowed without surrounding parentheses") }

Lib/test/test_syntax.py

@@ -1584,6 +1584,22 @@ SyntaxError: trailing comma not allowed without surrounding parentheses
 Traceback (most recent call last):
 SyntaxError: trailing comma not allowed without surrounding parentheses
 
+>>> import a from b
+Traceback (most recent call last):
+SyntaxError: Did you mean to use 'from ... import ...' instead?
+
+>>> import a.y.z from b.y.z
+Traceback (most recent call last):
+SyntaxError: Did you mean to use 'from ... import ...' instead?
+
+>>> import a from b as bar
+Traceback (most recent call last):
+SyntaxError: Did you mean to use 'from ... import ...' instead?
+
+>>> import a.y.z from b.y.z as bar
+Traceback (most recent call last):
+SyntaxError: Did you mean to use 'from ... import ...' instead?
+
 # Check that we dont raise the "trailing comma" error if there is more
 # input to the left of the valid part that we parsed.
 

Misc/NEWS.d/next/Core and Builtins/2022-10-31-22-55-34.gh-issue-98931.AoWZ-4.rst

@@ -0,0 +1,2 @@
+Improve the :exc:`SyntaxError` error message when the user types ``import x
+from y`` instead of ``from y import x``. Patch by Pablo Galindo