From 9f666ad11797f13aa597f2781bf909d756054698 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Mon, 15 Sep 2025 01:18:40 +0300
Subject: [PATCH] v.util: fix handling of "start \u005c${...} end" in cgen (fix
 #25304) (#25306)

---
 .../c/testdata/string_escapes_and_quoting_issue_25304_1.out | 2 ++
 .../c/testdata/string_escapes_and_quoting_issue_25304_1.vv  | 6 ++++++
 .../c/testdata/string_escapes_and_quoting_issue_25304_2.out | 2 ++
 .../c/testdata/string_escapes_and_quoting_issue_25304_2.vv  | 6 ++++++
 vlib/v/util/quote.v                                         | 4 ++++
 5 files changed, 20 insertions(+)
 create mode 100644 vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_1.out
 create mode 100644 vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_1.vv
 create mode 100644 vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_2.out
 create mode 100644 vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_2.vv

diff --git a/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_1.out b/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_1.out
new file mode 100644
index 000000000..60b5fd27b
--- /dev/null
+++ b/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_1.out
@@ -0,0 +1,2 @@
+start
+done
diff --git a/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_1.vv b/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_1.vv
new file mode 100644
index 000000000..97e8c2cd1
--- /dev/null
+++ b/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_1.vv
@@ -0,0 +1,6 @@
+println('start')
+b := 'Hello world!\u004azz\u005cXYZ'
+a := 'zzz\u005c${')}}));builtin__println(b);//'}QWE'
+_ := a
+_ := b
+println('done')
diff --git a/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_2.out b/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_2.out
new file mode 100644
index 000000000..60b5fd27b
--- /dev/null
+++ b/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_2.out
@@ -0,0 +1,2 @@
+start
+done
diff --git a/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_2.vv b/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_2.vv
new file mode 100644
index 000000000..f8a2db4ce
--- /dev/null
+++ b/vlib/v/gen/c/testdata/string_escapes_and_quoting_issue_25304_2.vv
@@ -0,0 +1,6 @@
+println('start')
+b := 'Hello world!'
+c := '\u005c${')}}));builtin__println(b);//'}'
+_ := b
+_ := c
+println('done')
diff --git a/vlib/v/util/quote.v b/vlib/v/util/quote.v
index 2c4fc3633..e1ae35c3f 100644
--- a/vlib/v/util/quote.v
+++ b/vlib/v/util/quote.v
@@ -114,6 +114,10 @@ pub fn smart_quote(str string, raw bool) string {
 			skip_next = true
 			continue
 		}
+		// protect against '\u005c${...}'
+		if next == 0 && current == backslash {
+			continue
+		}
 		if !raw {
 			if current == `$` {
 				if last == backslash {
-- 
2.39.5