From 18e28387722e3740b8786d964caaac375a0282bd Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Sat, 6 Dec 2025 18:24:15 +0100
Subject: [PATCH] - Hex escapes like `"\x80"` would be incorrectly lowered.
 #2623

---
 releasenotes.md                       |  1 +
 src/compiler/lexer.c                  |  5 ++---
 test/test_suite/clang/2002-03.c3t     |  4 +++-
 test/test_suite/literals/x_escape.c3t | 12 ++++++++++++
 4 files changed, 18 insertions(+), 4 deletions(-)
 create mode 100644 test/test_suite/literals/x_escape.c3t

diff --git a/releasenotes.md b/releasenotes.md
index 02758786d..b52f27ceb 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -10,6 +10,7 @@
 - Casting bitstruct to wider base type should be single step #2616.
 - Optional does not play well with bit ops #2618.
 - `Bytebuffer.grow` was broken #2622.
+- Hex escapes like `"\x80"` would be incorrectly lowered. #2623
 
 ### Stdlib changes
 
diff --git a/src/compiler/lexer.c b/src/compiler/lexer.c
index 2d3960a8c..c9afc1af9 100644
--- a/src/compiler/lexer.c
+++ b/src/compiler/lexer.c
@@ -858,9 +858,8 @@ static int append_esc_string_token(char *restrict dest, const char *restrict src
 			if (h < 0) return -1;
 			int l = char_hex_to_nibble(src[2]);
 			if (l < 0) return -1;
-			unicode_char = ((unsigned) h << 4U) + (unsigned)l;
-			scanned = 3;
-			break;
+			dest[(*pos)++] = (char)(((unsigned) h << 4U) + (unsigned)l);
+			return 3;
 		}
 		case 'u':
 		{
diff --git a/test/test_suite/clang/2002-03.c3t b/test/test_suite/clang/2002-03.c3t
index ab572335a..29da84267 100644
--- a/test/test_suite/clang/2002-03.c3t
+++ b/test/test_suite/clang/2002-03.c3t
@@ -60,7 +60,7 @@ fn char* foo() {
 @test.array = local_unnamed_addr global { %Test, %Test, [8 x %Test] } { %Test { i32 2, double 1.200000e+01 }, %Test { i32 3, double 2.400000e+01 }, [8 x %Test] zeroinitializer }, align 16
 @test.b = local_unnamed_addr global { [4 x i32], [4 x i32], { i32, i32, [2 x i32] }, [4 x i32] } { [4 x i32] [i32 1, i32 2, i32 3, i32 4], [4 x i32] [i32 5, i32 6, i32 7, i32 0], { i32, i32, [2 x i32] } { i32 8, i32 9, [2 x i32] zeroinitializer }, [4 x i32] zeroinitializer }, align 16
 @test.link = local_unnamed_addr global [3 x %Connection] [%Connection { i64 1, [10 x i8] c"link1\00\00\00\00\00", i64 10 }, %Connection { i64 2, [10 x i8] c"link2\00\00\00\00\00", i64 20 }, %Connection { i64 3, [10 x i8] c"link3\00\00\00\00\00", i64 30 }], align 16
-@.str = private unnamed_addr constant [4 x i8] c"\1F\C2\8B\00", align 1
+@.str = private unnamed_addr constant [3 x i8] c"\1F\8B\00", align 1
 @.str.7 = private unnamed_addr constant [32 x i8] c"*** Word \22%s\22 on line %d is not\00", align 1
 
 declare i32 @strcmp(ptr, ptr) #0
@@ -81,12 +81,14 @@ entry:
   store i32 0, ptr %lLS, align 4
   %i2b = icmp ne i32 %1, 0
   br i1 %i2b, label %if.then, label %if.exit
+
 if.then:                                          ; preds = %entry
   %2 = load i32, ptr %lLS, align 4
   %3 = load i32, ptr %asa, align 4
   %add = add i32 %2, %3
   store i32 %add, ptr %asa, align 4
   br label %if.exit
+
 if.exit:                                          ; preds = %if.then, %entry
   %4 = load i32, ptr %asa, align 4
   %5 = load double, ptr %val, align 8
diff --git a/test/test_suite/literals/x_escape.c3t b/test/test_suite/literals/x_escape.c3t
new file mode 100644
index 000000000..8e995b0ac
--- /dev/null
+++ b/test/test_suite/literals/x_escape.c3t
@@ -0,0 +1,12 @@
+// #target: macos-x64
+module test;
+import std;
+
+fn void main()
+{
+	char[] test = "\x80\x80\x79";
+    io::printfn("%s", test);
+}
+/* #expect: test.ll
+
+@.str = private unnamed_addr constant [4 x i8] c"\80\80y\00", align 1