From 85650bf1abc72f6b3607bf5946c190583117495f Mon Sep 17 00:00:00 2001
From: Scott Shawcroft <scott@tannewt.org>
Date: Thu, 5 Oct 2023 13:35:07 -0700
Subject: [PATCH] Fix re unescaping

---
 extmod/modure.c         |  4 ++++
 lib/re1.5/compilecode.c | 34 ++++++++++++++++++++++++++++------
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/extmod/modure.c b/extmod/modure.c
index 62aeed9b28..eb2dee2666 100644
--- a/extmod/modure.c
+++ b/extmod/modure.c
@@ -444,7 +444,11 @@ STATIC MP_DEFINE_CONST_DICT(re_locals_dict, re_locals_dict_table);
 
 STATIC MP_DEFINE_CONST_OBJ_TYPE(
     re_type,
+    #if CIRCUITPY
+    MP_QSTR_re,
+    #else
     MP_QSTR_ure,
+    #endif
     MP_TYPE_FLAG_NONE,
     print, re_print,
     locals_dict, &re_locals_dict
diff --git a/lib/re1.5/compilecode.c b/lib/re1.5/compilecode.c
index e6690d56b3..081c57441e 100644
--- a/lib/re1.5/compilecode.c
+++ b/lib/re1.5/compilecode.c
@@ -14,6 +14,27 @@
 #define EMIT_CHECKED(at, byte) (_emit_checked(at, code, byte, &err))
 #define PC (prog->bytelen)
 
+static char unescape(char c) {
+    switch (c) {
+        case 'a':
+            return '\a';
+        case 'b':
+            return '\b';
+        case 'f':
+            return '\f';
+        case 'n':
+            return '\n';
+        case 'r':
+            return '\r';
+        case 't':
+            return '\t';
+        case 'v':
+            return '\v';
+        default:
+            return c;
+    }
+}
+
 static void _emit_checked(int at, char *code, int val, bool *err) {
     *err |= val != (int8_t)val;
     if (code) {
@@ -34,14 +55,16 @@ static const char *_compilecode(const char *re, ByteProg *prog, int sizecode)
         case '\\':
             re++;
             if (!*re) return NULL; // Trailing backslash
+            term = PC;
             if (MATCH_NAMED_CLASS_CHAR(*re)) {
-                term = PC;
                 EMIT(PC++, NamedClass);
                 EMIT(PC++, *re);
-                prog->len++;
-                break;
+            } else {
+                EMIT(PC++, Char);
+                EMIT(PC++, unescape(*re));
             }
-            MP_FALLTHROUGH
+            prog->len++;
+            break;
         default:
             term = PC;
             EMIT(PC++, Char);
@@ -74,7 +97,7 @@ static const char *_compilecode(const char *re, ByteProg *prog, int sizecode)
                         c = RE15_CLASS_NAMED_CLASS_INDICATOR;
                         goto emit_char_pair;
                     } else {
-                        // CIRCUITPY TODO: handle unescape here again PR #1544
+                        c = unescape(c);
                     }
                 }
                 if (!c) return NULL;
@@ -84,7 +107,6 @@ static const char *_compilecode(const char *re, ByteProg *prog, int sizecode)
             emit_char_pair:
                 EMIT(PC++, c);
                 EMIT(PC++, *re);
-                // CIRCUITPY TODO handle unescape here again PR #1544
             }
             EMIT_CHECKED(term + 1, cnt);
             break;