commit 874ff65e0a70ff4fd1a67e85cd61d76adfcc219d
author Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Sat Jun 22 15:34:03 2019 -0700
committer GitHub <noreply@github.com> Sat Jun 22 15:34:03 2019 -0700
tree 56f0a7d275a2283001ce6ca87168d000c995438c
parent fa23bd286fb7719bd7601da0b713457589f5536f

bpo-35224: Reverse evaluation order of key: value in dict comprehensions (GH-14139)


… as proposed in PEP 572; key is now evaluated before value.

https://bugs.python.org/issue35224
(cherry picked from commit c8a35417db8853a253517a3e5190e174075c6384)

Co-authored-by: Jörn Heissler <joernheissler@users.noreply.github.com>

Python/ceval.c

diff --git a/Python/ceval.c b/Python/ceval.c
index 7063647..eddcc8d 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2944,8 +2944,8 @@
         }
 
         case TARGET(MAP_ADD): {
-            PyObject *key = TOP();
-            PyObject *value = SECOND();
+            PyObject *value = TOP();
+            PyObject *key = SECOND();
             PyObject *map;
             int err;
             STACK_SHRINK(2);

Python/compile.c

diff --git a/Python/compile.c b/Python/compile.c
index 4d3ecfe..7bdf406 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -4238,10 +4238,10 @@
             ADDOP_I(c, SET_ADD, gen_index + 1);
             break;
         case COMP_DICTCOMP:
-            /* With 'd[k] = v', v is evaluated before k, so we do
+            /* With '{k: v}', k is evaluated before v, so we do
                the same. */
-            VISIT(c, expr, val);
             VISIT(c, expr, elt);
+            VISIT(c, expr, val);
             ADDOP_I(c, MAP_ADD, gen_index + 1);
             break;
         default:
@@ -4327,10 +4327,10 @@
             ADDOP_I(c, SET_ADD, gen_index + 1);
             break;
         case COMP_DICTCOMP:
-            /* With 'd[k] = v', v is evaluated before k, so we do
+            /* With '{k: v}', k is evaluated before v, so we do
                the same. */
-            VISIT(c, expr, val);
             VISIT(c, expr, elt);
+            VISIT(c, expr, val);
             ADDOP_I(c, MAP_ADD, gen_index + 1);
             break;
         default: