From 254ec783411d9d16e51f1116f98918be2ef0e884 Mon Sep 17 00:00:00 2001
From: Pablo Galindo <Pablogsal@gmail.com>
Date: Fri, 3 Apr 2020 20:37:13 +0100
Subject: bpo-40147: Move the check for duplicate keywords to the compiler
 (GH-19289)

---
 Python/compile.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

(limited to 'Python/compile.c')

diff --git a/Python/compile.c b/Python/compile.c
index 01700e0e78..b1c1982fd2 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -4049,6 +4049,31 @@ maybe_optimize_method_call(struct compiler *c, expr_ty e)
     return 1;
 }
 
+static int
+validate_keywords(struct compiler *c, asdl_seq* keywords) {
+    int nkeywords = asdl_seq_LEN(keywords);
+    for (int i = 0; i < nkeywords; i++) {
+        keyword_ty key = ((keyword_ty)asdl_seq_GET(keywords, i));
+        if (key->arg == NULL) {
+            continue;
+        }
+        for (int j = i+1; j < nkeywords; j++) {
+            keyword_ty other = ((keyword_ty)asdl_seq_GET(keywords, j));
+            if (other->arg && !PyUnicode_Compare(key->arg, other->arg)) {
+                PyObject *msg = PyUnicode_FromFormat("keyword argument repeated: %U", key->arg);
+                if (msg == NULL) {
+                    return -1;
+                }
+                c->u->u_col_offset = other->col_offset;
+                compiler_error(c, PyUnicode_AsUTF8(msg));
+                Py_DECREF(msg);
+                return -1;
+            }
+        }
+    }
+    return 0;
+}
+
 static int
 compiler_call(struct compiler *c, expr_ty e)
 {
@@ -4165,6 +4190,10 @@ compiler_call_helper(struct compiler *c,
 {
     Py_ssize_t i, nseen, nelts, nkwelts;
 
+    if (validate_keywords(c, keywords) == -1) {
+        return 0;
+    }
+
     nelts = asdl_seq_LEN(args);
     nkwelts = asdl_seq_LEN(keywords);
 
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