Make imports in with blocks syntax errors

Author: pablogsal

Include/internal/pycore_symtable.h

@@ -127,6 +127,7 @@ typedef struct _symtable_entry {
     unsigned ste_has_conditional_annotations : 1; /* true if block has conditionally executed annotations */
     unsigned ste_in_conditional_block : 1; /* set while we are inside a conditionally executed block */
     unsigned ste_in_try_block : 1; /* set while we are inside a try/except block */
+    unsigned ste_in_with_block : 1; /* set while we are inside a with block */
     unsigned ste_in_unevaluated_annotation : 1; /* set while we are processing an annotation that will not be evaluated */
     int ste_comp_iter_expr; /* non-zero if visiting a comprehension range expression */
     _Py_SourceLocation ste_loc; /* source location of block */

Python/symtable.c

@@ -1754,6 +1754,13 @@ symtable_enter_type_param_block(struct symtable *st, identifier name,
 #define LEAVE_TRY_BLOCK(ST) \
     (ST)->st_cur->ste_in_try_block = in_try_block;
 
+#define ENTER_WITH_BLOCK(ST) \
+    int in_with_block = (ST)->st_cur->ste_in_with_block; \
+    (ST)->st_cur->ste_in_with_block = 1;
+
+#define LEAVE_WITH_BLOCK(ST) \
+    (ST)->st_cur->ste_in_with_block = in_with_block;
+
 #define ENTER_RECURSIVE() \
 if (Py_EnterRecursiveCall(" during compilation")) { \
     return 0; \
@@ -1826,6 +1833,14 @@ check_lazy_import_context(struct symtable *st, stmt_ty s, const char* import_typ
         return 0;
     }
 
+    /* Check if inside with block */
+    if (st->st_cur->ste_in_with_block) {
+        PyErr_Format(PyExc_SyntaxError,
+                    "lazy %s not allowed inside with blocks", import_type);
+        SET_ERROR_LOCATION(st->st_filename, LOCATION(s));
+        return 0;
+    }
+
     /* Check if inside function scope */
     if (st->st_cur->ste_type == FunctionBlock) {
         PyErr_Format(PyExc_SyntaxError,
@@ -2241,8 +2256,10 @@ symtable_visit_stmt(struct symtable *st, stmt_ty s)
         break;
     case With_kind: {
         ENTER_CONDITIONAL_BLOCK(st);
+        ENTER_WITH_BLOCK(st);
         VISIT_SEQ(st, withitem, s->v.With.items);
         VISIT_SEQ(st, stmt, s->v.With.body);
+        LEAVE_WITH_BLOCK(st);
         LEAVE_CONDITIONAL_BLOCK(st);
         break;
     }
@@ -2307,8 +2324,10 @@ symtable_visit_stmt(struct symtable *st, stmt_ty s)
             return 0;
         }
         ENTER_CONDITIONAL_BLOCK(st);
+        ENTER_WITH_BLOCK(st);
         VISIT_SEQ(st, withitem, s->v.AsyncWith.items);
         VISIT_SEQ(st, stmt, s->v.AsyncWith.body);
+        LEAVE_WITH_BLOCK(st);
         LEAVE_CONDITIONAL_BLOCK(st);
         break;
     }