From e6ad117ccb548c8411610571c92fa4094f275460 Mon Sep 17 00:00:00 2001
From: Bart Schaefer <schaefer@zsh.org>
Date: Wed, 15 Nov 2023 20:16:04 -0800
Subject: 52202: improve handling of quoting in ${var/pattern/replacement}

---
 ChangeLog              |  6 ++++++
 Src/lex.c              | 53 ++++++++++++++++++++++++++++++--------------------
 Src/subst.c            |  7 +++++++
 Test/D04parameter.ztst |  8 ++++----
 4 files changed, 49 insertions(+), 25 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 4f5c6b024..6baa171dc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2023-11-15  Bart Schaefer  <schaefer@zsh.org>
+
+	* 52202: Src/lex.c, Src/subst.c, Test/D04parameter.ztst: improve
+	handling of quoting in ${var/pattern/replacement}.  Still not
+	perfect, e.g., deeply nested expansions	in the pattern may fail.
+
 2023-11-14  Oliver Kiddle  <opk@zsh.org>
 
 	* github #106: Matt Koscica: Completion/Unix/Command/_tmux,
diff --git a/Src/lex.c b/Src/lex.c
index 33b17cc95..31b130b07 100644
--- a/Src/lex.c
+++ b/Src/lex.c
@@ -938,7 +938,7 @@ gettokstr(int c, int sub)
 {
     int bct = 0, pct = 0, brct = 0, seen_brct = 0, fdpar = 0;
     int intpos = 1, in_brace_param = 0, cmdsubst = 0;
-    int inquote, unmatched = 0;
+    int inquote, unmatched = 0, in_pattern = 0;
     enum lextok peek;
 #ifdef DEBUG
     int ocmdsp = cmdsp;
@@ -1160,7 +1160,7 @@ gettokstr(int c, int sub)
 	    if (bct-- == in_brace_param) {
 		if (cmdsubst)
 		    cmdpop();
-		in_brace_param = cmdsubst = 0;
+		in_brace_param = cmdsubst = in_pattern = 0;
 	    }
 	    c = Outbrace;
 	    break;
@@ -1309,7 +1309,8 @@ gettokstr(int c, int sub)
 			    lexbuf.ptr--, lexbuf.len--;
 			else
 			    break;
-		    }
+		    } else if (in_pattern && c == '/')
+			add(Bnull);
 		    add(c);
 		}
 		ALLOWHIST
@@ -1397,26 +1398,36 @@ gettokstr(int c, int sub)
 	     */
 	    c = Dash;
            break;
-       case LX2_BANG:
-           /*
-            * Same logic as Dash, for ! to perform negation in range.
-            */
-           if (seen_brct)
-               c = Bang;
-           else
-               c = '!';
-       }
-       add(c);
-       c = hgetc();
-       if (intpos)
+	case LX2_BANG:
+	    /*
+	     * Same logic as Dash, for ! to perform negation in range.
+	     */
+	    if (seen_brct)
+		c = Bang;
+	    else
+		c = '!';
+	case LX2_OTHER:
+	    if (in_brace_param) {
+		if (c == '/') {
+		    if (in_pattern == 0)
+			in_pattern = 2;
+		    else
+			--in_pattern;
+		}
+	    }
+	}
+	add(c);
+	c = hgetc();
+	if (intpos)
 	    intpos--;
-       if (lexstop)
+	if (lexstop)
 	    break;
-       if (!cmdsubst && in_brace_param && act == LX2_STRING &&
-	   (c == '|' || c == Bar || inblank(c))) {
-	   cmdsubst = in_brace_param;
-	   cmdpush(CS_CURSH);
-       }
+	if (!cmdsubst && in_brace_param && act == LX2_STRING &&
+	    (c == '|' || c == Bar || inblank(c))) {
+	    cmdsubst = in_brace_param;
+	    cmdpush(CS_CURSH);
+	} else if (in_pattern == 2 && c != '/')
+	    in_pattern = 1;
     }
   brk:
     if (errflag) {
diff --git a/Src/subst.c b/Src/subst.c
index 60d850feb..4ef1d1269 100644
--- a/Src/subst.c
+++ b/Src/subst.c
@@ -3088,6 +3088,13 @@ paramsubst(LinkList l, LinkNode n, char **str, int qt, int pf_flags,
 			chuck(ptr);
 		    else
 			ptr++;
+		} else if (c == Dnull) {
+		    chuck(ptr);
+		    while (*ptr && *ptr != c)
+			ptr++;
+		    if (*ptr == Dnull)
+			chuck(ptr);
+		    ptr--;	/* Outer loop is about to increment */
 		}
 	    }
 	    replstr = (*ptr && ptr[1]) ? ptr+1 : "";
diff --git a/Test/D04parameter.ztst b/Test/D04parameter.ztst
index c2008582c..69a4fd3ec 100644
--- a/Test/D04parameter.ztst
+++ b/Test/D04parameter.ztst
@@ -2762,13 +2762,13 @@ F:behavior, see http://austingroupbugs.net/view.php?id=888
 
  slash='/'
  print -r -- x${slash/'/'}y
--Df:(users/28784) substituting a single-quoted backslash, part #1: slash
+0:(users/28784) substituting a single-quoted backslash, part #1: slash
 >xy
 
  single_quote="'"
- print -r -- x${single_quote/'/'}y
--Df:(users/28784) substituting a single-quoted backslash, part #2: single quote
->x/y
+ print -r -- x${single_quote/$'/'}y
+0:(users/28784) substituting a single-quoted backslash, part #2: single quote
+>x'y
 
  control="foobar"
  print -r -- x${control/'bar'}y
-- 
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