From 294e985e2efce147604cda48937532bb0650579f Mon Sep 17 00:00:00 2001
From: maximilize <3752128+maximilize@users.noreply.github.com>
Date: Sun, 28 Jun 2026 00:16:46 +0200
Subject: [PATCH] filter: support nested {} alternates in glob filters - fixes
 #7220

---
 fs/filter/glob.go      | 31 +++++++++++++++++--------------
 fs/filter/glob_test.go |  9 +++++++--
 2 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/fs/filter/glob.go b/fs/filter/glob.go
index 40c0c56e2..ac93f4c7d 100644
--- a/fs/filter/glob.go
+++ b/fs/filter/glob.go
@@ -83,7 +83,7 @@ func globToRegexp(glob string, pathMode bool, addAnchors bool, ignoreCase bool)
 		buf := re.Bytes()
 		buf[len(buf)-1] = c
 	}
-	inBraces := false
+	braceDepth := 0
 	inBrackets := 0
 	slashed := false
 	inRegexp := false    // inside {{ ... }}
@@ -152,25 +152,27 @@ func globToRegexp(glob string, pathMode bool, addAnchors bool, ignoreCase bool)
 		case ']':
 			return nil, fmt.Errorf("mismatched ']' in glob %q", glob)
 		case '{':
-			if inBraces {
-				if last == '{' {
-					inRegexp = true
-					inBraces = false
-				} else {
-					return nil, fmt.Errorf("can't nest '{' '}' in glob %q", glob)
-				}
+			if braceDepth > 0 && last == '{' {
+				// {{ starts a raw regexp section. The '(' written by
+				// the first '{' wraps the regexp, so undo its depth.
+				// (An escaped \{ does not open a brace, so braceDepth
+				// guards against treating \{{ as a regexp section.)
+				inRegexp = true
+				braceDepth--
 			} else {
-				inBraces = true
+				// Open a brace group. These may nest, so each level
+				// emits its own balanced '(' ... ')'.
+				braceDepth++
 				_ = re.WriteByte('(')
 			}
 		case '}':
-			if !inBraces {
+			if braceDepth <= 0 {
 				return nil, fmt.Errorf("mismatched '{' and '}' in glob %q", glob)
 			}
 			_ = re.WriteByte(')')
-			inBraces = false
+			braceDepth--
 		case ',':
-			if inBraces {
+			if braceDepth > 0 {
 				_ = re.WriteByte('|')
 			} else {
 				_, _ = re.WriteRune(c)
@@ -189,7 +191,7 @@ func globToRegexp(glob string, pathMode bool, addAnchors bool, ignoreCase bool)
 	if inBrackets > 0 {
 		return nil, fmt.Errorf("mismatched '[' and ']' in glob %q", glob)
 	}
-	if inBraces {
+	if braceDepth != 0 {
 		return nil, fmt.Errorf("mismatched '{' and '}' in glob %q", glob)
 	}
 	if inRegexp {
@@ -209,7 +211,8 @@ var (
 	// Can't deal with
 	//   / or ** in {}
 	//   {{ regexp }}
-	tooHardRe = regexp.MustCompile(`({[^{}]*(\*\*|/)[^{}]*})|\{\{|\}\}`)
+	//   nested {} (the inner braces are opaque to the directory split below)
+	tooHardRe = regexp.MustCompile(`({[^{}]*(\*\*|/)[^{}]*})|\{\{|\}\}|\{[^{}]*\{`)
 
 	// Squash all /
 	squashSlash = regexp.MustCompile(`/{2,}`)
diff --git a/fs/filter/glob_test.go b/fs/filter/glob_test.go
index a20a77775..f1b8e7dc9 100644
--- a/fs/filter/glob_test.go
+++ b/fs/filter/glob_test.go
@@ -24,6 +24,8 @@ func TestGlobStringToRegexp(t *testing.T) {
 		{`'.' '+' '(' ')' '|' '^' '$'`, `'\.' '\+' '\(' '\)' '\|' '\^' '\$'`, ``},
 		{`*.jpg`, `.*\.jpg`, ``},
 		{`a{b,c,d}e`, `a(b|c|d)e`, ``},
+		{`a{b,{c,d}}e`, `a(b|(c|d))e`, ``},
+		{`{a,{b,c},{d,{e,f}}}`, `(a|(b|c)|(d|(e|f)))`, ``},
 		{`potato**`, ``, `too many stars`},
 		{`potato**sausage`, ``, `too many stars`},
 		{`*.p[lm]`, `.*\.p[lm]`, ``},
@@ -32,7 +34,7 @@ func TestGlobStringToRegexp(t *testing.T) {
 		{`***`, ``, `too many stars`},
 		{`ab]c`, ``, `mismatched ']'`},
 		{`ab[c`, ``, `mismatched '[' and ']'`},
-		{`ab{x{cd`, ``, `can't nest`},
+		{`ab{x{cd`, ``, `mismatched '{' and '}'`},
 		{`ab{}}cd`, ``, `mismatched '{' and '}'`},
 		{`ab}c`, ``, `mismatched '{' and '}'`},
 		{`ab{c`, ``, `mismatched '{' and '}'`},
@@ -92,6 +94,8 @@ func TestGlobPathToRegexp(t *testing.T) {
 		{`'.' '+' '(' ')' '|' '^' '$'`, `(^|/)'\.' '\+' '\(' '\)' '\|' '\^' '\$'$`, ``},
 		{`*.jpg`, `(^|/)[^/]*\.jpg$`, ``},
 		{`a{b,c,d}e`, `(^|/)a(b|c|d)e$`, ``},
+		{`a{b,{c,d}}e`, `(^|/)a(b|(c|d))e$`, ``},
+		{`{a,b/{c,d}/**}`, `(^|/)(a|b/(c|d)/.*)$`, ``},
 		{`potato**`, `(^|/)potato.*$`, ``},
 		{`potato**sausage`, `(^|/)potato.*sausage$`, ``},
 		{`*.p[lm]`, `(^|/)[^/]*\.p[lm]$`, ``},
@@ -100,7 +104,7 @@ func TestGlobPathToRegexp(t *testing.T) {
 		{`***`, ``, `too many stars`},
 		{`ab]c`, ``, `mismatched ']'`},
 		{`ab[c`, ``, `mismatched '[' and ']'`},
-		{`ab{x{cd`, ``, `can't nest`},
+		{`ab{x{cd`, ``, `mismatched '{' and '}'`},
 		{`ab{}}cd`, ``, `mismatched '{' and '}'`},
 		{`ab}c`, ``, `mismatched '{' and '}'`},
 		{`ab{c`, ``, `mismatched '{' and '}'`},
@@ -158,6 +162,7 @@ func TestGlobToDirGlobs(t *testing.T) {
 		{`a/b`, []string{"a/"}},
 		{`a/b/*.{jpg,png,gif}`, []string{"a/b/", "a/"}},
 		{`/a/{jpg,png,gif}/*.{jpg,png,gif}`, []string{"/a/{jpg,png,gif}/", "/a/", "/"}},
+		{`a/{b,{c,d}}/*.jpg`, []string{"/**"}},
 		{`a/{a,a*b,a**c}/d/`, []string{"/**"}},
 		{`/a/{a,a*b,a/c,d}/d/`, []string{"/**"}},
 		{`/a/{{.*}}/d/`, []string{"/**"}},